Age-dependent effects of testosterone on spatial memory in male rats.

Decreased spatial memory is common in aging populations and reduces their quality of life. Although its role is still controversial, low testosterone (T) may contribute to impaired cognition in aged men. This study aimed to identify the role of T in age-related deficiencies in spatial memory among male rats. Young adult (3 months old) and aged (21 months old) Wistar rats were assigned to independent groups: intact, orchidectomized, or orchidectomized + subcutaneous pellets of T propionate. The phases of spatial memory acquisition (4 daily trials/4 days) and spatial memory retention (1 trial/day, 3 and 12 days after acquisition) were evaluated using the Barnes maze. Compared with young adults, aged intact rats took longer to find the goal, made more mistakes, and showed only slight improvements in goal sector exploration across the acquisition period. The young orchidectomized rats showed no improvement in performance over the days during the acquisition phase. T treatment in hormonally deprived old rats produced a small improvement in goal sector exploration and number of errors during the acquisition phase. Meanwhile, in young adults, this treatment improved the goal sector searching in the retention phase (12 days after acquisition training). Our results suggested that age-related spatial memory deficits cannot be entirely explained by the decline in T levels; however, this androgen produced subtle and mild beneficial effects on spatial memory in young and old males. Taken together, our findings suggest age differences in the role of T on spatial memory in males.

Influence of the type of childhood violence on cannabis abuse and dependence among adolescents: a systematic review and meta-analysis. / Tipos de violencia en la infancia que inciden en el abuso y dependencia de cannabis entre adolescentes: una revisión sistemática y metaanálisis.

The use of cannabis for recreational purposes has increased worldwide, and the proportion of cannabis users in the adolescent population is high. Susceptibility to cannabis use involves various factors, including childhood adversity; however, the effects of different types of violence on cannabis use have not been evaluated. The aim of this review was to analyze the effects of different types of violence on cannabis use in adolescence. We searched electronic databases (PubMed, Science Direct, Web of Science, Ovid and CONRICyT) using the following algorithm: (("Cannabis" OR "Marijuana Smoking" OR "Marijuana Abuse") AND ("Child Abuse" OR "Domestic Violence" AND "Adolescent")), considering all articles published up to November 3th, 2017. Odds ratios (ORs) were calculated for the effects of experiencing different types of violence during childhood on cannabis use. Six studies, which represented 10 843 adolescents of both sexes, were ultimately included in the systematic review and meta-analysis. Three types of early-life adversity were associated with cannabis abuse/dependence: physical abuse (OR: 1.58, 95% CI [1.01-2.46]), sexual abuse (OR: 2.35, 95% CI [1.64-3.35]), and witnessing violence (OR: 3.22, 95% CI [0.63-16.54]). The results indicated that two specific types of child maltreatment, sexual and physical abuse, were critical factors affecting vulnerability to cannabis use in adolescence. The number of studies examining other types of violence was limited. The results highlighted the importance of enhancing efforts to prevent violence, particularly sexual abuse, as part of integral programs designed to prevent cannabis abuse and dependence.

El uso recreativo de cannabis ha incrementado en todo el mundo, principalmente en la población adolescente. Se ha propuesto que la adversidad en la infancia contribuye al consumo de esta droga. El objetivo de esta revisión sistemática y metaanálisis fue analizar el efecto de diferentes tipos de violencia en la infancia sobre el consumo de cannabis en la adolescencia. Se realizó una búsqueda en diferentes bases de datos (PubMed, Science Direct, Web of Science, Ovid y CONRICyT) usando los términos de búsqueda: (("Cannabis" OR "Marijuana Smoking" OR "Marijuana Abuse") AND ("Child Abuse" OR "Domestic Violence" AND "Adolescent")), considerando todos los artículos publicados hasta el 3 de noviembre de 2017. Se calcularon los Odds Ratio (OR) del consumo de cannabis en adolescentes, para los diferentes tipos de abuso infantil, así como sus intervalos de confianza del 95% (IC 95%). Se identificaron seis estudios, que incluyeron 10 843 adolescentes de uno u otro sexo. La asociación entre la violencia y el abuso/dependencia de cannabis en la adolescencia mostró los siguientes valores: abuso físico (OR: 1,58, IC 95% [1,01­2,46]), abuso sexual (OR: 2,35, IC 95% [1,64­3,35]), y ser testigo de violencia (OR: 3,22, IC 95% [0,63­16,54]). Los resultados muestran que el abuso sexual o físico durante etapas tempranas de la vida aumenta el riesgo de consumo de cannabis en la adolescencia. Los estudios que evaluaron otras formas de violencia fueron escasos. Los resultados destacan la importancia de diseñar programas integrales para reducir el uso y dependencia de cannabis mediante estrategias enfocadas a la prevención de la violencia en la infancia.

Tipos de violencia en la infancia que inciden en el abuso y dependencia de cannabis entre adolescentes: una revisión sistemática y metaanálisis / Influence of the type of childhood violence on cannabis abuse and dependence among adolescents: a systematic review and meta-analysis

El uso recreativo de cannabis ha incrementado en todo el mundo, principalmente en la población adolescente. Se ha propuesto que la adversidad en la infancia contribuye al consumo de esta droga. El objetivo de esta revisión sistemática y metaanálisis fue analizar el efecto de diferentes tipos de violencia en la infancia sobre el consumo de cannabis en la adolescencia. Se realizó una búsqueda en diferentes bases de datos (PubMed, Science Direct, Web of Science, Ovid y CONRICyT) usando los términos de búsqueda: (("Cannabis" OR "Marijuana Smoking" OR "Marijuana Abuse") AND ("Child Abuse" OR "Domestic Violence" AND "Adolescent")), considerando todos los artículos publicados hasta el 3 de noviembre de 2017. Se calcularon los Odds Ratio (OR) del consumo de cannabis en adolescentes, para los diferentes tipos de abuso infantil, así como sus intervalos de confianza del 95% (IC 95%). Se identificaron seis estudios, que incluyeron 10 843 adolescentes de uno u otro sexo. La asociación entre la violencia y el abuso/dependencia de cannabis en la adolescencia mostró los siguientes valores: abuso físico (OR: 1,58, IC 95% [1,01-2,46]), abuso sexual (OR: 2,35, IC 95% [1,64-3,35]), y ser testigo de violencia (OR: 3,22, IC 95% [0,63-16,54]). Los resultados muestran que el abuso sexual o físico durante etapas tempranas de la vida aumenta el riesgo de consumo de cannabis en la adolescencia. Los estudios que evaluaron otras formas de violencia fueron escasos. Los resultados destacan la importancia de diseñar programas integrales para reducir el uso y dependencia de cannabis mediante estrategias enfocadas a la prevención de la violencia en la infancia

The use of cannabis for recreational purposes has increased worldwide, and the proportion of cannabis users in the adolescent population is high. Susceptibility to cannabis use involves various factors, including childhood adversity; however, the effects of different types of violence on cannabis use have not been evaluated. The aim of this review was to analyze the effects of different types of violence on cannabis use in adolescence. We searched electronic databases (PubMed, Science Direct, Web of Science, Ovid and CONRICyT) using the following algorithm: (("Cannabis" OR "Marijuana Smoking" OR "Marijuana Abuse") AND ("Child Abuse" OR "Domestic Violence" AND "Adolescent")), considering all articles published up to November 3th, 2017. Odds ratios (ORs) were calculated for the effects of experiencing different types of violence during childhood on cannabis use. Six studies, which represented 10 843 adolescents of both sexes, were ultimately included in the systematic review and meta-analysis. Three types of early-life adversity were associated with cannabis abuse/dependence: physical abuse (OR: 1.58, 95% CI [1.01-2.46]), sexual abuse (OR: 2.35, 95% CI [1.64-3.35]), and witnessing violence (OR: 3.22, 95% CI [0.63-16.54]). The results indicated that two specific types of child maltreatment, sexual and physical abuse, were critical factors affecting vulnerability to cannabis use in adolescence. The number of studies examining other types of violence was limited. The results highlighted the importance of enhancing efforts to prevent violence, particularly sexual abuse, as part of integral programs designed to prevent cannabis abuse and dependence

Role of Estradiol in the Expression of Genes Involved in Serotonin Neurotransmission: Implications for Female Depression.

BACKGROUND: In women, changes in estrogen levels may increase the incidence and/or symptomatology of depression and affect the response to antidepressant treatments. Estrogen therapy in females may provide some mood benefits as a single treatment or might augment clinical response to antidepressants that inhibit serotonin reuptake. OBJECTIVE: We analyzed the mechanisms of estradiol action involved in the regulation of gene expression that modulates serotonin neurotransmission implicated in depression. METHOD: Publications were identified by a literature search on PubMed. RESULTS: The participation of estradiol in depression may include regulation of the expression of tryptophan hydroxylase-2, monoamine oxidase A and B, serotonin transporter and serotonin-1A receptor. This effect is mediated by estradiol binding to intracellular estrogen receptor that interacts with estrogen response elements in the promoter sequences of tryptophan hydroxylase-2, serotonin transporter and monoamine oxidase-B. In addition to directly binding deoxyribonucleic acid, estrogen receptor can tether to other transcription factors, including activator protein 1, specificity protein 1, CCAAT/enhancer binding protein ß and nuclear factor kappa B to regulate gene promoters that lack estrogen response elements, such as monoamine oxidase-A and serotonin 1A receptor. CONCLUSION: Estradiol increases tryptophan hydroxylase-2 and serotonin transporter expression and decreases the expression of serotonin 1A receptor and monoamine oxidase A and B through the interaction with its intracellular receptors. The understanding of molecular mechanisms of estradiol regulation on the protein expression that modulates serotonin neurotransmission will be helpful for the development of new and more effective treatment for women with depression.

Relationship between androgen deficiency and memory impairment in aging and Alzheimer’s disease.

Aging and Alzheimer’s disease (AD) are associated with a declination of cognition and memory, whose severity increases in AD. Recent investigations point to a greater participation of neurofibrillary tangles (NFTs) than that of senile plaques, as responsible for cognitive impairment in AD and normal aging. On the other hand, aging is related with reduced levels of dehydroepiandrosterone (DHEA) and its sulfate (DHEA-S) as well as testosterone (T). Basic and clinical studies give evidence that hypoandrogenism is associated with memory impairment. Accordingly, some animal studies show that the administration of these hormones improves the performance of cognitive tasks. However, effects of DHEA, DHEA-S, and T in the clinical setting, are not clear in part because of the balance between the benefits and risks of hormone therapy in aging subjects and because the cellular mechanism underlying its effects on memory in old age and related pathologies are unknown. The objective of this review is to analyze the role of DHEA, DHEA-S, and T, on memory in normal aging and in AD, and to determine whether these hormones modulate the hyperphosphorylation of tau protein, a molecular marker in AD pathology. The method used in the review included articles from the PubMed database, using the following search terms: DHEA, DHEA-S, T, memory, androgen deprivation therapy, tau protein, aging, and AD. Finally, we analyze the use of these steroids as an adjunct in the treatment of memory deficits in aging subjects and AD patients.

La deficiencia de andrógenos y su relación con el deterioro en la memoria en el envejecimiento y en la enfermedad de Alzheimer / Relationship between androgen deficiency and memory impairment in aging and Alzheimer's disease

El envejecimiento y la enfermedad de Alzheimer (EA) se asocian con una declinación de la cognición y la memoria, cuya gravedad aumenta en la EA. Varias investigaciones apuntan a una mayor participación de los ovillos neurofbrilares respecto a las placas seniles, como responsables del deterioro cognitivo en la EA y en el envejecimiento normal. Por otro lado, el envejecimiento se relaciona con una reducción en los niveles de dehidroepiandrosterona (DHEA) y su sulfato (DHEA-S), así como de testosterona (T); algunas evidencias básicas y clínicas indican que esta condición se asocia con deterioro en la memoria. Varios estudios en animales revelan que la administración de DHEA, DHEA-S y T mejoran la ejecución de tareas cognitivas. Sin embargo, el efecto de estas hormonas en el ámbito clínico no es claro, en parte por el balance entre los beneficios y los riesgos de una terapia hormonal en pacientes ancianos, así como por el desconocimiento de los mecanismos celulares que subyacen a sus efectos sobre la memoria en la vejez y en patologías relacionadas. El objetivo de esta revisión narrativa es analizar el papel de los esteroides DHEA, DHEA-S y T en la memoria en el envejecimiento normal y en la EA, así como la modulación en la hiperfosforilación de la proteína tau, un marcador molecular de la patología de la EA, por estas hormonas. El método empleado en esta revisión fue una búsqueda en la base de datos de Pubmed con los siguientes términos: DHEA, DHEA-S, T, memoria, terapia de privación de andrógenos, proteína tau, envejecimiento y EA. Finalmente, se analizará el empleo de estos esteroides como un coadyuvante en el tratamiento de las alteraciones de memoria en sujetos envejecidos y en pacientes con EA (AU)

Aging and Alzheimer's disease (AD) are associated with a declination of cognition and memory, whose severity increases in AD. Recent investigations point to a greater participation of neurofibrillary tangles (NFTs) than that of senile plaques, as responsible for cognitive impairment in AD and normal aging. On the other hand, aging is related with reduced levels of dehydroepiandrosterone (DHEA) and its sulfate (DHEA-S) as well as testosterone (T). Basic and clinical studies give evidence that hypoandrogenism is associated with memory impairment. Accordingly, some animal studies show that the administration of these hormones improves the performance of cognitive tasks. However, effects of DHEA, DHEA-S, and T in the clinical setting, are not clear in part because of the balance between the benefits and risks of hormone therapy in aging subjects and because the cellular mechanism underlying its effects on memory in old age and related pathologies are unknown. The objective of this review is to analyze the role of DHEA, DHEA-S, and T, on memory in normal aging and in AD, and to determine whether these hormones modulate the hyperphosphorylation of tau protein, a molecular marker in AD pathology. The method used in the review included articles from the PubMed database, using the following search terms: DHEA, DHEA-S, T, memory, androgen deprivation therapy, tau protein, aging, and AD. Finally, we analyze the use of these steroids as an adjunct in the treatment of memory deficits in aging subjects and AD patients (AU)

Corrigendum to "Young-Adult Male Rats' Vulnerability to Chronic Mild Stress Is Reflected by Anxious-Like instead of Depressive-Like Behaviors".

[This corrects the article DOI: 10.1155/2016/5317242.].

La melatonina como un factor promotor de la diferenciación neuronal: implicaciones en el tratamiento de las demencias / Melatonin as a neuronal differentiation factor: therapeutic implications for dementia

Dementias are progressive and neurodegenerative neuropsychiatry disorders, with a high worldwide prevalence. These disorders affect memory and behavior, causing impairment in the performance of daily activities and general disability in the elders. Cognitive impairment in these patients is related to anatomical and structural alterations at cellular and sub-cellular levels in the Central Nervous System. In particular, amyloid plaques and neurofibrillar tangles have been defined as histopathological hallmarks of Alzheimer's disease. Likewise, oxidative stress and neuroinflammation are implicated in the etiology and progression of the disease. Neuronal precursors from human olfactory neuroepithelium have been recently characterized as an experimental model to identify neuropsychiatric disease biomarkers. Moreover, this model not only allows the study of neuropsychiatric physiopathology, but also the process of neurodevelopment at cellular, molecular and pharmacological levels. This review gathers the evidence to support the potential therapeutic use of melatonin for dementias, based on its antioxidant properties, its anti-inflammatory effect in the brain, and its ability to inhibit both tau hyper-phosphorylation and amyloid plaque formation. Furthermore, since melatonin stimulates neurogenesis, and promotes neuronal differentiation by inducing the early stages of neuritogenesis and dendrite formation, it has been suggested that melatonin could be useful to counteract the cognitive impairment in dementia patients.

Las demencias son enfermedades neuropsiquiátricas, progresivas, neurodegenerativas y con una alta prevalencia a nivel mundial. Ocupan uno de los primeros lugares como enfermedades que causan incapacidad en los adultos mayores. En estos pacientes el Sistema Nervioso Central presenta alteraciones anatómico-estructurales a nivel celular y subcelular que se asocian con deficiencias cognitivas. En particular, en la enfermedad de Alzheimer se han caracterizado marcadores histopatológicos como las placas amiloides y las marañas neurofibrilares. Se sabe que el estrés oxidativo y la neuroinflamación participan en la etiología y el desarrollo de la enfermedad. Recientemente se caracterizó a los precursores neuronales del neuroepitelio olfatorio humano como un modelo experimental adecuado para identificar biomarcadores de rasgo y para estudiar la fisiopatología de diversas enfermedades neuropsiquiátricas, así como el proceso del neurodesarrollo, a nivel celular, molecular y farmacológico. En este trabajo se presenta la evidencia que sustenta que la melatonina puede ser útil en el tratamiento de las demencias, por su capacidad antioxidante, por su efecto anti-inflamatorio, así como por el efecto inhibidor de la hiperfosforilación de la proteina tau y de la formación de placas amiloides. Además, al estimular la formación de nuevas neuronas, la neuritogénesis en sus etapas tempranas y la formación de dendritas, la melatonina podría contribuir a contrarrestar la pérdida de las funciones cognitivas que se observa en estos padecimientos.

Melatonin modulates cytoskeletal organization in the rat brain hippocampus.

Melatonin concentration in plasma reaches high levels during the night and synchronizes body rhythms with the photoperiod. Previous evidence obtained in cultured cells suggests that melatonin synchronizes cytoskeletal re-arrangements at nocturnal plasma concentration. In this study, we determined the amount of microtubules and microfilaments in the rat hippocampus as an index of cytoskeletal organization in rats submitted to a photoperiodic regime. Additionally, these parameters were determined in control rats, sham rats, pinealectomized rats, and rats that were pinealectomized and treated with melatonin for 1 week. The results showed an increase in both the amount of microfilaments in the hippocampus of rats sacrificed in the dark phase, and in melatonin levels. In addition, a decrease in both microfilament and microtubule amounts occurred in pinealectomized rats. In contrast, melatonin treatment partially reestablished actin and tubulin proportions organized in microfilaments and microtubules, respectively. The results indicate that actin organization in microfilaments was associated with both the photoperiod and with melatonin levels. Together, the data support that cytoskeletal organization is regulated rhythmically by melatonin in synchrony with the photoperiod.

Alteraciones del ciclo circadiano en las enfermedades psiquiátricas: papel sincronizador de la melatonina en el ciclo sueño-vigilia y la polaridad neuronal / Circadian cycle alterations in psychiatric diseases: melatonin role as a synchronizer of sleep-awake cycle and the neuronal polarity

Circadian rhythms are oscillations of physiological functions. The period of their oscillation is about 24 h, and can be synchronized by environmental periodic signals as night-day cycle. The endogenous periodical changes depend on various structural elements of the circadian system which consists of the effectors, the secondary oscillators, the synchronizers and the circadian pacemaker. In mammalian species, the physiological function better understood respect their oscillation pattern are the synthesis and release of several hormones (i.e. cortisol and melatonin), the body temperature, the sleep-awake cycle, the locomotive activity, cell proliferation, neuronal activity among other rhythms. The Suprachiasmatic nucleus is the main circadian pacemarker in mammals; its oscillation keeps the circadian system synchronized particularly with respect to the environment photo period. When light reaches the pigment melanopsin in ganglionar neurons in the retina, the photoperiod signal is sent to Suprachiasmatic nucleus, and its postsinaptic neurons distributes the temporal signal to pheripheral oscillators by nervous or humoral pathways. Among the oscillators, the pineal gland is a peripheral one modulated by Suprachiasmatic nucleus. At night, the indolamine melatonin is synthesized and released from pinealocytes, and reaches other peripheral oscillators. Melatonin interacts with membrane receptors on Suprachiasmatic nucleus pacemarker neurons, reinforcing the signal of the photoperiod. In mammals, exogenous melatonin synchronizes several circadian rhythms including locomotive activity and melatonin release. When this indolamine is applied directly into the Suprachiasmatic nucleus, it produces a phase advance of the endogenous melatonin peak and increases the amplitude of the oscillation. In humans, melatonin effect on the circadian system is evident because it changes the circadian rhythms phase in subjects with advanced sleep-phase syndrome, night workers or blind people. Also it reduces jet lag symptoms enhancing sleep quality and reseting the circadian system to local time. Melatonin effects on circadian rhythms indicate their role as a chronobiotic, since decreased daily melatonin levels that occur with age and in neuropsychiatric disorders are associated with disturbances in the sleep-awake cycle. In particular, it has been described that Alzheimer's disease patients have disturbed sleep-awake cycle and have decreased serum melatonin levels. Sleep disorders in Alzheimer's disease patients decrease when they are treated with melatonin. Moreover, sleep disturbances have been observed in bipolar disorder patients and often precede relapses of insomnia-associated mania and hypersomnia-associated depression. These disturbances are linked to delayed- and advanced- phases of circadian rhythms or arrhythmia; therefore, it has been suggested that bipolar disorder patients could be treated with light and dark therapy. In depressed patients, the levels of melatonin are low throughout the 24 hour period and have a delayed onset of the indolamine concentration and showed an advance of its peak. Schizophrenic patients have decreased levels in the plasmatic melatonin in both phases of the light-dark cycle. Melatonin administration to these patients increases their sleep efficiency. In addition, melatonin acts as a neuroprotector because of its potent antioxidant action and through its cytoskeletal modulation properties. In neurodegenerative animal models, its protector effect has been observed using okadaic acid. This neurotoxin is employed for reproducing cytoskeletal damage in neurons and increased oxidative stress levels, which are molecular events similar to those that occur in Alzheimer's disease. In N1E-115 cell cultures incubated with okadaic acid, the administration of melatonin diminishes hyperphosphorylated tau and oxidative stress levels, and prevents the neurocytoskeletal damage caused by the neurotoxin. Although it is known that melatonin plays a key role in the circadian rhythms entrainment, little is known about its synchronizing effects at molecular and structural level. In algae, it has been observed a link between morphological changes and the light-dark cycle and it is known that shape is determinated by the cytoskeletal structure. In particular, the alga Euglena gracilis changes its shape two times per day under the effect of a daily light-dark cycle. This alga has a long shape when there is a higher photosynthetic capacity at the half period of the day; on the contrary, it showed a rounded shape at the end of 24 h cycle. Also, the influence of the cell shape changes on the photosynthetic reactions was investigated by altering them with drugs that disrupt the cytoskeletal structure as cytochalasin B and colchicine. Both inhibitors blocked the rhythmic shape changes and the photo-synthetic rhythm. Moreover, there are some reports about cytoskeletal changes in plants targeted by circadian rhythms. Guarda cells of Vicia faba L. showed a diurnal cycle on the alpha and beta tubulin levels. In addition, it has been proposed that melatonin synchronizes different body rhythms through cytoskeletal rearrangements. In culture cells, nanomolar melatonin concentrations cause an increase in both the polimerization rate and microtubule formation through calmodulin antagonism. A cyclic pattern produced by melatonin in the actin microfilament organization has been demonstrated in canine kidney cells. Cyclic incubation of MDCK cells with nanomolar concentrations of melatonin, resembling the cyclic pattern of secretion and release to plasma produces a microfilament reorganization and the formation of domes. Studies in animals are controvertial regarding if the amount of microtubules in different tissues varies cyclically. In rats and baboons, melatonin administration or exposure of rats to darkness induced an increased number of microtubules in the pineal gland. However, in the hypothalamus, the exposure of rats to light resulted in an increase in the microtubular protein content. Similarly, (X-tubulin mRNA was augmented during the light phase in the hypothalamus, hippocampus and cortex. By contrast, in rats maintained in constant darkness, a decreased level in the tubulin content was observed in the visual cortex. Additional information on cycle variations observed in cytoskeletal molecules indicated that beta actin mRNA levels are lower during the day in the hippocampus and cortex. But no change was observed in actin protein levels in the cerebral cortex. However, increased levels of actin and its mRNA were observed in the hypothalamus. Exogenous melatonin administration at onset of night decreased the amount of actin in the hypothalamus, while the actin mRNA levels decreased when the administration was realized in the morning. In this review we will describe the synchronizer role of melatonin in the sleep-awake cycle and in the organization of cytoskeletal proteins and their mRNAs. Also, we will describe alterations in the melatonin secretion rhythm associated with a neuronal cytoskeleton disorganization in the neuropsychiatric diseases such as Alzheimer, depression, bipolar disorder and schizophrenia.

Los ritmos circadianos son patrones de oscilación con un periodo cercano a 24h que se observan en los procesos fisiológicos. En los mamíferos se han descrito funciones biológicas con regulación circádica tal como el ciclo sueño-vigilia. La administración de la melatonina, una indolamina secretada por la glándula pineal, sincroniza los ritmos circadianos. En los humanos, este efecto se ha estudiado en sujetos con síndrome de <

Haloperidol causes cytoskeletal collapse in N1E-115 cells through tau hyperphosphorylation induced by oxidative stress: Implications for neurodevelopment.

Haloperidol a typical antipsychotic commonly used in the treatment of schizophrenia causes neuronal damage and extrapiramidal symptoms after several years of treatment. These symptoms have been associated with increased levels of oxidative stress. Reactive oxygen species produce cytoskeletal collapse and an excessive phosphorylation of tau, a microtubule-associated protein that plays a key role in microtubule stabilization, and in growth cone and neurite formation, which are cytoskeletal phenotypes that participate in neurodevelopment. Thus, we hypothesized that haloperidol produces neurocytoskeletal disorganization by increasing free radicals and tau hyperphosphorylation, and consequently, the loss of neurodevelopmental cytoskeletal phenotypes, neurites and growth cones. The purpose of this work was the characterization of neuronal cytoskeletal changes caused by haloperidol in neuroblastoma N1E-115 cells. We also studied the mechanisms by which haloperidol causes cytoskeletal changes. The results showed that haloperidol at 100microM caused a complete cytoskeleton collapse in the majority of the cells. Melatonin, a free radical scavenger, blocks tau hyperphosphorylation, and microtubule disorganization caused by haloperidol in a dose-response mode. Additionally, the indole blocks lipoperoxide formation in haloperidol treated cells. The results indicate that free radicals and tau hyperphosphorylation produced by haloperidol caused a cytoskeletal collapse and the lost of growth cones and neurites. These effects were blocked by melatonin. Data suggest that extrapiramidal symptoms in schizophrenic patients can be produced by cytoskeletal disorganization during adult brain neurodevelopment after prolonged haloperidol treatment that can be prevented by melatonin.

La melatonina: un coadyuvante potencial en el tratamiento de las demencias / Melatonin: A potential coadyuvant in dementia treatment

Alzheimer's disease is characterized by a progressive neuronal death and a lost of memory and cognition that unable the patient to perform daily tasks. Cytoskeleton alterations, identified as a major histopathologic hallmark of neurodegenerative diseases, occur in dementia. In this disease, neurons have pathologic inclusions containing fibrillar aggregates of hyperphosphorylated tau protein in absence of amyloid deposits. Abundant senile plaques and neurofibrillary tangles constitute the two major neuropathologic lesions present in hippocampal, neocortical, and forebrain cholinergic brain regions of Alzheimer's patients. Hyperphosphorylated tau and the subsequent formation of paired helical filaments loses the capabilities for maintaining highly asymmetrical neuronal polarity. Thus, in brains with a high content of hyperphosphorylated tau, microtubules are disassembled, the highly asymmetrical neural shape is lost and an impairment of axonal transport is produced together with a lost of dendrite arborizations. In addition, brain damage caused by free radicals occurs in Alzheimer's disease. This illness involves a reduction of the endogenous antioxidant enzyme system, increased senile-plaque formation, cytoskeletal collapse, and neuronal apoptosis induced by oxidative stress. Acetylcholinesterase inhibitors are the most commonly used compounds in the treatment of neurodegenerative diseases. However, despite their wide use in the treatment of Alzheimer's disease, these compounds have limited therapeutic effects and cause undesirable effects. Therefore it is necessary to investigate new alternatives in the Alzheimer's disease treatment. Considering that neurodegenerative diseases are cytoskeleton disorders, this cellular structure could be a drug target for therapeutic approaches by restoring normal cytoskeleton structure and by precluding damage caused by oxygen-reactive species. In this regard, melatonin, the indole secreted by the pineal gland during the dark phase of the photoperiod, has two important properties that may be useful for the treatment of mental disorders. One is that melatonin is a potent free-radical scavenger and the other is that this indole is a cytoskeletal modulator. A neuroprotective role for melatonin was initially suggested due to its free-radical scavenger properties. Melatonin detoxifies the highly toxic hydroxyl radical as well as the peroxyl radical, peroxynitrite anion, nitric oxide, and singlet oxygen, all of which can damage brain macromolecules. Moreover, melatonin stimulates the activity of antioxidative enzymes including superoxide dismutase, glutathione peroxidase, and glutathione reductase. Also, it is a lipophilic molecule able to cross the blood-brain barrier. All these properties make melatonin a highly effective pharmacologic agent against free-radical damage in the brain. Also, it is a useful neuroprotector in dementia because it synchronize the body rhythms with the photoperiod, which are altered in Alzheimer's disease and because normal circadian secretion of melatonin and sleep-wake cycle can be restored by the indolamine administration. Additionally, cytoskeletal modulation by melatonin is another relevant property of the indole for neurodegenerative diseases treatment. Direct assessment of melatonin effects on cytoskeletal organization in neuronal cells indicated that the indole promotes neuritogenesis in N1E-115 neuroblastoma cells at plasma melatonin concentration. Neurite formation is a complex process critical to establish synaptic connectivity that is lost in Alzheimer's disease. Neuritogenesis takes place by a dynamic cytoskeletal organization that involves microtubule enlargement, microfilament arrangement, and intermediate-filament reorganization. In particular, microtubule assembly participates in neurite formation elicited by melatonin through antagonism to calmodulin. Also, selective activation of protein kinase C (PKC) alpha by melatonin participates in vimentin intermediate filament rearrangements and actin dynamics for neurite outgrowth in neuroblastoma cells. In N1E-115 cells, melatonin at plasma and cerebrospinal fluid concentration caused an increase in microfilament arrays in stress fibers and their thickening, as well as increased growth cone formation, and augmented number of cells with microspikes. Recently, it was demonstrated that melatonin increased both the number of N1E-115 cells with filopodia and with long neurites through both PKC activation and Rho-associated kinase (ROCK) stimulation. The utility of melatonin to prevent damage in the cytoskeletal structure produced by neurodegenerative processes was demonstrated in N1E-115 neuroblastoma cells cultured with okadaic acid (OA), a specific inhibitor of the serine/threonine proteins phosphatases 1 and 2A that induces molecular and structural changes similar to those found in Alzheimer's disease. Melatonin prevented microtubule disruption followed by cell-shape changes and increased lipid peroxidation and apoptosis induced by OA. Melatonin effects on altered cytoskeletal organization induced by OA are dose-dependent and effects were observed at plasma -and cerebrospinal-fluid concentrations of the indole. These data support that melatonin can be useful in the treatment of neurodegenerative diseases by both its action on the cytoskeleton and by its free-radical scavenger properties.

La enfermedad de Alzheimer es una enfermedad neurodegenerativa progresiva que cursa con una deficiencia en las capacidades cognitivas, así como con la presencia de síntomas psiquiátricos y alteraciones conductuales. Las características histopatológicas más importantes en la enfermedad de Alzheimer son la formación de placas seniles, los ovillos neurofibrilares y un incremento en el estrés oxidativo. La polaridad estructural y la morfología neuronal se pierden en la enfermedad de Alzheimer. La proteína tau se encuentra anormalmente fosforilada, los microtúbulos se despolimerizan, se pierden la forma asimétrica de las neuronas y la conectividad sináptica, y se interrumpe el transporte axoplasmático. Asimismo, se ha sugerido que la inhibición o la pérdida en el balance de la formación de neuronas en el hipocampo puede participar en la fisiopatología de la enfermedad de Alzheimer debido a que el cerebro no puede reparar el daño neuronal y consecuentemente induce la pérdida de la cognición. Los agentes colinérgicos son los medicamentos más aceptados en el tratamiento de la enfermedad de Alzheimer en una etapa en que los síntomas se clasifican de medios a moderados. Sin embargo, el tratamiento de pacientes con enfermedad de Alzheimer grave es limitado. Por lo anterior se requiere la búsqueda de nuevas alternativas para el tratamiento de esta enfermedad. La melatonina es una indolamina que actúa como un potente antioxidante, como un modulador de la organización del citoesqueleto así como un factor de diferenciación celular. Diversos estudios han sugerido que la melatonina tiene un efecto neuroprotector por su capacidad de captar radicales libres. La melatonina disminuye la lipoperoxidación y la apoptosis producida por la administración de ácido ocadáico (AO) o peróxido de hidrógeno (H2O2). Se sabe que las especies reactivas de oxígeno producen alteraciones en la organización del citoesqueleto e influyen el estado de fosforilación de la proteína tau y que la melatonina previene la fosforilación de la proteína tau debido a su actividad antioxidante. Se ha descrito que la melatonina modula el arreglo de los microfilamentos de actina y la formación de fibras de tensión en las células Madin-Darby canine kidney (MDCK) por medio de una interacción concertada de la indolamina con la calmodulina y con la proteína cinasa C (PKC) y la participación de la proteína cinasa dependiente de Rho (ROCK). Asimismo, la melatonina participa en las etapas tempranas de la formación de neuritas en las células N1E-115 por medio de ROCK. Otros estudios han indicado que la melatonina previene el daño en el citoesqueleto producido por el AO en las células N1E-115. El AO se ha utilizado para reproducir en células en cultivo las alteraciones en el citoesqueleto y el incremento en el estrés oxidativo que ocurren en las neuronas de pacientes con enfermedad de Alzheimer. La melatonina en estas células previene la retracción del citoesqueleto, efecto del AO. La red del citoesqueleto se mantiene en el citoplasma y en las neuritas de las células N1E-115 cultivadas con melatonina, no obstante que sean tratadas con el AO posteriormente. Recientemente, se demostró que en las células de neuroblastoma N1E-115 incubadas con melatonina se previene la hiperfosforilación de la proteína tau causada por el AO. Aunado a lo anterior, se ha demostrado que la melatonina modula la formación de neuronas nuevas en un modelo in vitro utilizando células embrionarias y de corteza cerebral de ratón. La formación de neuronas inducida por la melatonina se corroboró utilizando células precursoras aisladas de animales adultos así como en animales adultos, y se encontró que la indolamina moduló la sobrevida de las células nuevas formadas, así como la diferenciación de éstas en neuronas nuevas. Las evidencias presentadas en esta revisión indican que la melatonina puede ser útil como un coadyuvante en el tratamiento de las demencias.

El neurocitoesqueleto: un nuevo blanco terapéutico para el tratamiento de la depresión

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Summary Postmortem and neuroimaging studies of Major Depressive Disorder patients have revealed changes in brain structure. In particular the reduction in prefrontal cortex and in hippocampus volume has been described. In addition, a variety of cytoarchitectural abnormalities have been described in limbic regions of major depressive patients. Decrease in neuronal density has been reported in the hippocampus, a structure involved in declarative, spatial and contextual memory. This structure undergoes atrophy in depressive illness along with impairment in cognitive function. Several studies suggest that reduction of hyppocampus volume is due to the decreased cell density and diminished axons and dendrites. These changes suggested a disturbance of normal neuronal polarity, established and maintained by elements of the neuronal cytoskeleton. In this review we describe evidence supporting that neuronal cytoskeleton is altered in depression. In addition, we present data indicating that the cytoskeleton can be a potential target in depression treatment. Neurons are structural polarized cells with a highly asymmetric shape. The cytoskeleton plays a key role in maintain the structural polarization in neurons which are differentiated in two structural domains: The somato-dendritic domain and the axonal domain. This differentiated asymmetric shape, depends of the cytoskeletal organization which support, transport and sorts various molecules and organelles in different compartments within the cell. Microtubules determine the asymmetrical shape and axonal structure of neurons and form the tracks for intracellular transport, of crucial importance in axonal flux. Actin microfilaments are involved in force generation during organization of neuronal shape in cellular internal and external movements and participate in growth cone formation. This important cytoskeletal organization preceed the formation of neurites that eventually will differentiated into axons or dendrites, a process that also comprises a dynamic assembly of the three cytoskeletal components. Intermediate filaments are known in neurons as neurofilaments spatially intercalated with microtubules in the axons and facilitate the radial axonal growth and the transport. Neurofilaments also act supporting other components of the cytoskeleton. All changes and movements of the cytoskeletal organization are coordinated by cytoskeletal associated proteins such as the protein tau and the microtubule associated proteins (MAPs). Also, specific interactions of microfilaments, microtubules and filaments which are regulated by extracellular signals take place in modulation of the cytoskeletal rearrangements. The polarized structure and the highly asymmetric shape of neurons are essentials for neuronal physiology and it appears to be lost in patients with a Major Depressive Disorder. Histopathological studies have shown that the hippocampus and frontal cortex of patients with major depressive disorder have diminished soma size, as well as, have decreased dendrites and cellular volume. Dendrite formation depends mainly in microfilaments organization as well as in polarization of the microtubule binding protein MAP2. In addition, there is a decreased synaptic connectivity and an increased oxidative stress, which originates abnormalities in the cytoskeletal structure. These neuronal changes originate alterations in the brain functionality such as decreased cognitive abilities and affective dis-regulations, usually encountered in patients with depression. Therefore, pathologic lesions implicating an altered cytoskeletal organization, may have an important role in decreased cognitive functions, observed in depression, as well as in changes in the brain volume, explained by a lost of neuronal processes such as axons, dendrite processes or dendritic spines, rather than by loss of neuronal or glial cell bodies. This explanation is supported by light immunomicroscopy of brain slices postmortem stained with specific antibodies. Psychological stress which causes oxidative stress has also been suggested to cause a decrease of neuronal volume in the prefrontal cortex, altering the synaptic connections established with the hippocampus. This conclusion was drawn from studies in animal models of psychological stress associated with molecular measurements where defects in the expression of MAP1 and sinaptophysin were found, suggesting that defects in cytoskeletal associated proteins could underlie some cytoarchitectural abnormalities described in depression. Together all the evidence accumulated indicates that major depression illness and bipolar depression are mental disorders that involve loss of axons and dendrites in neurons of the Central Nervous System, that in consequence cause disruption of synaptic connectivity. Thus is possible that depression can be considered as a cytoskeletal disorder, therefore this cellular structure could be a drug target for therapeutic approaches by restoring normal cytoskeleton structure and precluding damage caused by oxygen-reactive species. In this regard, melatonin, the hormone secreted by pineal gland during dark phase of the photoperiod, has two important properties that can be useful in treatment of mental disorders. First, the melatonin is a potent free-radical scavenger and second this hormone governs the assembly of the three main cytoskeletal components modulating the cytoskeletal organization. This notion is supported by direct action of melatonin effects on cytoskeletal organization in neuronal cells. In N1E-115 neuroblastoma cells, melatonin induced a two-fold increase in number of cells with neurites 1 day after plating; the effect lasting up to 4 days. Induction of neurite outgrowths is optimal at 1 nM melatonin and in presence of hormone the cells grew as clusters with long neurites forming a fine network to make contact with adjacent cells. Immunofluorescence of N1E-115 cells cultured under these conditions showed tubulin staining in long neurite processes connecting cells to each other. Neurite formation is a complex process that is critical to establish synaptic connectivity. Neuritogenesis takes place by a dynamic cytoskeletal organization that involves microtubule enlargement, microfilament arrangement, and intermediate- filament reorganization. In particular, it is known that vimentin intermediate filaments are reorganized during initial stages of neurite outgrowth in neuroblastoma cells and cultured hippocampal neurons. Evidence has been published indicating that increase in microtubule assembly participates in neurite formation elicited by melatonin antagonism to calmodulin. Moreover, recently it was reported that melatonin precludes cytoskeletal damage produced by high levels of free radicals produced by hydrogen peroxide, as well as, damage caused by higher doses of the antypsychotics haloperidol and clozapine. N1E-115 cells incubated with either 100 uM hydrogen peroxide, 100 uM haloperidol, or 100 uM clozapine undergo a complete cytoskeletal retraction around the nucleus. By contrast, NIE-115 cells incubated with hydrogen peroxide, clozapine, or haloperidol followed by the nocturnal cerebrospinal fluid concentration of melatonin (100 nM) showed a well preserved cytoskeleton and neuritogenesis. Thus melatonin is a neuroprotective compound, since protects the neurocytoskeletal organization against damage caused by high concentrations of antipsychotics and oxidative stress. As mentioned previously, polarity is intrinsic to neuronal function. In neurons, somatodendritic domain receives and decodes incoming information and axonal domain delivers information to target cells. Progressive loss of neuronal polarity is one of the histopathologic events in depression. Cytoskeletal collapse underlie the lost of structural polarity and it is known that precede neuronal death and disappearance of synaptic connectivity. Drugs that prevent the loss of polarity and cytoskeleton retraction intrinsic to these diseases, as well as damage in cytoskeletal structure produced by oxidative stress can be extremely useful in depression treatment. Melatonin is a potent free-radical scavenger that also acts as a cytoskeleton regulator; thus, we speculate that this hormone could be useful in prevention and alleviation of psychiatry diseases with synaptic connectivity disruption. Clinical trials show that melatonin administration is followed by alleviation of circadian disturbances and cognitive function in various neuropsychiatry diseases. Moreover, in depression, melatonin improves sleep. Thus, as suggestive as this information appears, controlled clinical trials will be necessary to investigate the beneficial effects of melatonin and other drugs in the depression treatment.

Phosphorylation-dephosphorylation imbalance of cytoskeletal associated proteins in neurodegenerative diseases.

Neurons are highly asymmetric cells, specialized to transmit and receive information through axons and dendrites. Neuronal morphology is determined by a particular cytoskeletal organization that provides the framework for distinct axonal and dendritic structures. Dynamic cytoskeletal rearrangements occur during neurite outgrowth, neuronal plasticity and synaptic connectivity. In this work, we summarize the evidences that support that these dynamic changes are mainly governed by phosphorylation-dephosphorylation equilibrium of cytoskeleton and cytoskeletal-associated proteins. In addition, we describe evidence supporting that in neurodegeneration an imbalance of this equilibrium occurs, followed by disarray of the cytoskeleton in axons and dendrites with the consequent disruption of synaptic connectivity. Finally we discuss current strategies and patents that could contribute to re-establish a balance in the brain of patients with dementia.