Precision Medicine in Alzheimer's Disease: Investigating Comorbid Common Biological Substrates in the Rat Model of Amyloid Beta-Induced Toxicity.

Alzheimer's disease (AD), one of the most widespread neurodegenerative disorder, is a fatal global burden for the elder population. Although many efforts have been made, the search of a curative therapy is still ongoing. Individuating phenotypic traits that might help in investigating treatment response is of growing interest in AD research. AD is a complex pathology characterized by many comorbidities, such as depression and increased susceptibility to pain perception, leading to postulate that these conditions may rely on common biological substrates yet to be determined. In order to investigate those biological determinants to be associable with phenotypic traits, we used the rat model of amyloid beta-induced toxicity. This established model of early phase of AD is obtained by the intracerebroventricular injection of soluble amyloid beta1-42 (Aß) peptide 7 days before performing experiments. In this model, we have previously reported increased immobility in the forced swimming test, reduced cortical serotonin levels and subtle alterations in the cognitive domain a depressive-like phenotype associated with subtle alteration in memory processes. In light of evaluating pain perception in this animal model, we performed two different behavioral tests commonly used, such as the paw pressure test and the cold plate test, to analyze mechanical hyperalgesia and thermal allodynia, respectively. Behavioural outcomes confirmed the memory impairment in the social recognition test and, compared to sham, Aß-injected rats showed an increased selective susceptibility to mechanical but not to thermal stimulus. Behavioural data were then corroborated by neurochemical and biochemical biomarker analyses either at central or peripheral level. Data showed that the peptide injection evoked a significant increase in hypothalamic glutamate, kynurenine and dopamine content, while serotonin levels were reduced. Plasma Cystatin-C, a cysteine protease, was increased while serotonin and melatonin levels were decreased in Aß-injected rats. Urinary levels paralleled plasma quantifications, indicating that Aß-induced deficits in pain perception, mood and cognitive domain may also depend on these biomarkers. In conclusion, in the present study, we demonstrated that this animal model can mimic several comorbid conditions typical of the early phase of AD. Therefore, in the perspective of generating novel therapeutic strategies relevant to precision medicine in AD, this animal model and the biomarkers evaluated herein may represent an advantageous approach.

Celecoxib Exerts Neuroprotective Effects in ß-Amyloid-Treated SH-SY5Y Cells Through the Regulation of Heme Oxygenase-1: Novel Insights for an Old Drug.

The formation and aggregation of amyloid-ß-peptide (Aß) into soluble and insoluble species represent the pathological hallmarks of Alzheimer's disease (AD). Over the last few years, however, soluble Aß (sAß) prevailed over fibrillar Aß (fAß) as determinant of neurotoxicity. One of the main therapeutic strategies for challenging neurodegeneration is to fight against neuroinflammation and prevent free radical-induced damage: in this light, the heme oxygenase/biliverdin reductase (HO/BVR) system is considered a promising drug target. The aim of this work was to investigate whether or not celecoxib (CXB), a selective inhibitor of the pro-inflammatory cyclooxygenase-2, modulates the HO/BVR system and prevents lipid peroxidation in SH-SY5Y neuroblastoma cells. Both sAß (6.25-50 nM) and fAß (1.25-50 nM) dose-dependently over-expressed inducible HO (HO-1) after 24 h of incubation, reaching statistical significance at 25 and 6.25 nM, respectively. Interestingly, CXB (1-10 µM, for 1 h) further enhanced Aß-induced HO-1 expression through the nuclear translocation of the transcriptional factor Nrf2. Furthermore, 10 µM CXB counteracted the Aß-induced ROS production with a mechanism fully dependent on HO-1 up-regulation; nevertheless, 10 µM CXB significantly counteracted only 25 nM sAß-induced lipid peroxidation damage in SH-SY5Y neurons by modulating HO-1. Both carbon monoxide (CORM-2, 50 nM) and bilirubin (50 nM) significantly prevented ROS production in Aß-treated neurons and favored both the slowdown of the growth rate of Aß oligomers and the decrease in oligomer/fibril final size. In conclusion, these results suggest a novel mechanism through which CXB is neuroprotective in subjects with early AD or mild cognitive impairment.

The Heme Oxygenase/Biliverdin Reductase System as Effector of the Neuroprotective Outcomes of Herb-Based Nutritional Supplements.

Over the last few years, several preclinical studies have shown that some herbal products, such as ferulic acid, Ginkgo biloba, and resveratrol, exert neuroprotective effects through the modulation of the heme oxygenase/biliverdin reductase system. Unfortunately, sufficient data supporting the shift of knowledge from preclinical studies to humans, particularly in neurodegenerative diseases, are not yet available in the literature. The purpose of this review is to summarize the studies and the main results achieved on the potential therapeutic role of the interaction between the heme oxygenase/biliverdin reductase system with ferulic acid, G. biloba, and resveratrol. Some critical issues have also been reported, mainly concerning the safety profile and the toxicological sequelae associated to the supplementation with the herbs mentioned above, based on both current literature and specific reports issued by the competent Regulatory Authorities.

Curcumin and Heme Oxygenase: Neuroprotection and Beyond.

Curcumin is a natural polyphenol component of Curcuma longa Linn, which is currently considered one of the most effective nutritional antioxidants for counteracting free radical-related diseases. Several experimental data have highlighted the pleiotropic neuroprotective effects of curcumin, due to its activity in multiple antioxidant and anti-inflammatory pathways involved in neurodegeneration. Although its poor systemic bioavailability after oral administration and low plasma concentrations represent restrictive factors for curcumin therapeutic efficacy, innovative delivery formulations have been developed in order to overwhelm these limitations. This review provides a summary of the main findings involving the heme oxygenase/biliverdin reductase system as a valid target in mediating the potential neuroprotective properties of curcumin. Furthermore, pharmacokinetic properties and concerns about curcumin's safety profile have been addressed.

Effects of n-3 PUFA enriched and n-3 PUFA deficient diets in naïve and Aß-treated female rats.

Depression is one of the most common psychiatric diseases and the prevalence of depressive symptoms in women is almost twice compared to men, although the reasons of this gender difference are not fully understood yet. Recently, soluble Aß1-42 peptide has been receiving great importance in the development of depression, also since depression is highly comorbid with Alzheimer's disease and other neurodegenerative illnesses. Accordingly, we have previously shown that central Aß injection is able to elicit depressive-like phenotype in male rats. In the present study, we reproduced for the first time the Aß-induced depressive-like model in female rats, evaluating behavioural and neurochemical outcomes. Moreover, we studied the effect of lifelong exposure to either n-3 PUFA enriched or n-3 PUFA deficient diet, in female rats, both intact and after central Aß administration. Our results confirmed the Aß-induced depressive-like profile also in female rats. Moreover, chronic exposure to n-3 PUFA deficient diet led to highly negative alterations in behavioural and neurochemical parameters, while lifelong exposure to n-3 PUFA enriched diet was able to restore the Aß-induced depressive-like profile in female rats. In conclusion, the Aß-induced depressive-like profile was reversed by n-3 PUFA supplementation, indicating a possible therapeutic role of n-3 PUFA in the treatment of the burden of depressive disorders.

Celecoxib Prevents Cognitive Impairment and Neuroinflammation in Soluble Amyloid ß-treated Rats.

Recent findings suggest that soluble forms of amyloid-ß (sAß) peptide contribute to synaptic and cognitive dysfunctions in early stages of Alzheimer's disease (AD). On the other hand, neuroinflammation and cyclooxygenase-2 (COX-2) enzyme have gained increased interest as key factors involved early in AD, although the signaling pathways and pathophysiologic mechanisms underlying a link between sAß-induced neurotoxicity and inflammation are still unclear. Here, we investigated the effects of selective COX-2 enzyme inhibition on neuropathological alterations induced by sAß administration in rats. To this purpose, animals received an intracerebroventricular (icv) injection of predominantly monomeric forms of sAß and, 7 days after, behavioral as well as biochemical parameters and neurotransmitter alterations were evaluated. During this period, rats also received a sub-chronic treatment with celecoxib. Biochemical results demonstrated that icv sAß injection significantly increased both COX-2 and pro-inflammatory cytokines expression in the hippocampus (Hipp) of treated rats. In addition, the number of hypertrophic microglial cells and astrocytes were upregulated in sAß-treated group. Interestingly, rats treated with sAß showed long-term memory deficits, as confirmed by a significant reduction of discrimination index in the novel object recognition test, along with reduced brain-derived neurotrophic factor expression and increased noradrenaline levels in the Hipp. Systemic administration of celecoxib prevented behavioral dysfunctions, as well as biochemical and neurotransmitter alterations. In conclusion, our results suggest that sAß neurotoxicity might be associated to COX-2-mediated inflammatory pathways and that early treatment with selective COX-2 inhibitor might provide potential remedies to counterbalance the sAß-induced effects.

Ferulic Acid Improves Cognitive Skills Through the Activation of the Heme Oxygenase System in the Rat.

Over the last years, many studies reported on the antioxidant effects of ferulic acid (FA) in preclinical models of dementia through the activation of the heme oxygenase/biliverdin reductase (HO/BVR) system. However, only a few studies evaluated whether FA could improve neurological function under milder conditions, such as psychological stress. The aim of this study was to investigate the effects of FA (150 mg/kg intraperitoneal route) on cognitive function in male Wistar rats exposed to emotional arousal. Animals were randomly assigned to two experimental groups, namely not habituated or habituated to the experimental context, and the novel object recognition test was used to evaluate their cognitive performance. The administration of FA significantly increased long-term retention memory in not habituated rats. Ferulic acid increased the expression of HO-1 in the hippocampus and frontal cortex of not habituated rats only, whereas HO-2 resulted differently modulated in these cognitive brain areas. No significant effects on either HO-1 or HO-2 or BVR were observed in the cerebellum of both habituated and not habituated rats. Ferulic acid activated the stress axis in not habituated rats, as shown by the increase in hypothalamic corticotrophin-releasing hormone levels. Pre-treatment with Sn-protoporphyrin-IX [0.25 µmol/kg, intracerebroventricular route (i.c.v.)], a well-known inhibitor of HO activity through which carbon monoxide (CO) and biliverdin (BV) are generated, abolished the FA-induced improvement of cognitive performance only in not habituated rats, suggesting a role for HO-derived by-products. The CO-donor tricarbonyldichlororuthenium (II) (30 nmol/kg i.c.v.) mimicked the FA-related improvement of cognitive skills only in not habituated rats, whereas BV did not have any effect in any group. In conclusion, these results set the stage for subsequent studies on the neuropharmacological action of FA under conditions of psychological stress.

Visceral Fat Dysfunctions in the Rat Social Isolation Model of Psychosis.

Medication with neuroleptics has been associated with adipose tissue dysfunctions and, in particular, with increased visceral fat amount. However, several studies suggested that antipsychotic treatment might not be the main responsible of fat mass accumulation, as this has been also described in not treated psychotic patients. One of the most used "drug-free" rodent models of psychosis is the social isolation rearing of young adult rats, which provides a non-pharmacologic method of inducing long-term alterations reminiscent of symptoms seen in psychotic patients. Recent data highlighted a crucial role of redox imbalance in adipose tissue dysfunctions, in terms of decreased antioxidant defense and increased reactive oxygen species (ROS). Here, we investigated possible oxidative stress-related biomolecular alterations associated with visceral fat increase in 7 week isolated rats. To this purpose, we quantified total and visceral fat amount by using dual-energy X-ray (DEXA) absorptiometry. On visceral fat, we analyzed the expression of specific ROS-producer genes (Nox1, Nox4, Hmox-1), antioxidant enzymes (Prdx1 and Ucp-1) and oxidative stress-induced damage markers (Cidea, Slc2a4, and Acacb). The impact of oxidative stress on beta3-adrenergic receptors (Adrb3), at both mRNA and protein level, was also assessed. We found that 7 weeks of social isolation induced an increase in total and visceral fat, associated with a decrease in Prdx1 (mRNA and protein) as well as Ucp-1 mRNA levels and an enhanced expression of Nox1 (mRNA and protein) and Hmox-1 mRNA. No differences were detected in Nox4 mRNA levels between grouped and isolated animals. Elevations in Cidea, Slc2a4, and Acacb expression in visceral fat of isolated animals accounted for oxidative stress-related damage in this tissue, further associated with a significant increase in Adrb3 mRNA and protein. Our results provide a novel understanding of the pathological link existing among psychosocial stress-induced psychosis, adipose tissue dysfunctions and redox imbalance, opening new therapeutic perspectives for the treatment of alterations in peripheral tissues associated with this mental disorder.

Antidepressant drugs for beta amyloid-induced depression: A new standpoint?

Mounting evidence suggests that depression represents a risk factor and an early manifestation of Alzheimer's disease (AD). Neuropsychiatric symptoms may derive from neurobiological changes in specific brain areas and may be considered prodromal of dementia. We have previously reported the depressive-like profile in rats receiving a single intracerebroventricular injection of soluble amyloid beta protein (ßA). Here, we verified the effect of different classes of antidepressants on the ßA-induced depressive behavior and on cortical monoamine levels. To these purposes, the forced swimming test was performed and cortical levels of serotonin (5-HT) and noradrenaline (NA) were quantified by high performance liquid chromatography (HPLC). We found that acute fluoxetine (20mg/kg, s.c.), reboxetine (10mg/kg, s.c.), and ketamine (15mg/kg, i.p.) significantly reduced the immobility in ßA-treated rats compared to controls. Fluoxetine and reboxetine reversed 5-HT reduction, while ßA-induced NA increase was further enhanced by all treatments. Treatments with fluoxetine, reboxetine and ketamine were able to revert soluble ßA-induced decrease of cortical BDNF levels, while only fluoxetine and ketamine, but not reboxetine, had the same effects on cortical NGF expression. Moreover, plasma soluble ßA-levels were lowered by fluoxetine, but not reboxetine and ketamine, treatments. Our data suggest that different classes of antidepressants yield a short-acting effect on rat soluble ßA-induced depressive profile. Thus, we hypothesize a novel common mechanism of action of these drugs also based upon a "ßA lowering" effect. Although further investigations are still needed, our study might open a new scenario for unravelling the molecular antidepressant mechanisms of these drugs.

The contribution of transgenic and nontransgenic animal models in Alzheimer's disease drug research and development.

Over the last few years, several papers have become available in the literature on both the main hallmarks of Alzheimer's disease (AD) and the several intracellular pathways whose alteration is responsible for its onset and progression. The use of transgenic and nontransgenic animal models has played a key role in achieving such a remarkable amount of preclinical data, allowing researchers to dissect the cellular changes occurring in the AD brain. In addition, the huge amount of preclinical evidence arising from these animal models was necessary for the further clinical development of pharmacological agents capable of interfering with most of the impaired neural pathways in AD patients. In this respect, a significant role is played by the dysfunction of excitatory and inhibitory neurotransmission responsible for the cognitive and behavioral symptoms described in AD patients. The aim of this review is to summarize the main animal models that contributed toward unraveling the pathological changes in neurotransmitter synthesis, release, and receptor binding in AD preclinical studies. The review also provides an updated description of the current pharmacological agents - still under clinical development - acting on the neurotransmitter systems.

Lifelong Nutritional Omega-3 Deficiency Evokes Depressive-Like State Through Soluble Beta Amyloid.

Recent evidence pointed out that the prevalence of depression has reached epidemic proportions in last decades. This increase has been linked to many environmental factors, among these the influence of dietary factors has gained great attention. In particular, it has been reported that low n-3 polyunsaturated fatty acid (n-3 PUFA) intake in diet is correlated to the development of depressive and anxiety-like symptoms. Furthermore, maternal malnutrition is a widely accepted risk factor for developing mental illness in later adulthood; among others, depression has been strongly associated to this event. On the other hand, we have previously found that acute intracerebral injection of the soluble beta amyloid 1-42 (Aß1-42) peptide induces a depressive-like behavior in rats, associated to altered hypothalamic-pituitary-adrenal (HPA) axis activation and reduced cortical serotonin and neurotrophin levels. The aim of the present work was to study the effect of pre- and post-natal (5 weeks post-weaning) exposure to diets differently enriched in n-3, n-6, as well as n-6/n-3 PUFA balanced, on immobility time displayed on the forced swimming test (FST), along with neuroendocrine quantification in offspring rats. Results showed that n-6 PUFA-enriched diet increased depressive- and anxiety-like behaviors, as shown by the elevation in the immobility time in the FST test and self-grooming in the open field test. Those effects were accompanied by reduced cortical serotonin, high plasmatic corticosterone and hypothalamic corticotropin-releasing factor levels. Finally, enhanced plasmatic Aß1-42 levels after n-6 PUFA diet and reduced plasmatic Aß1-42 levels after n-3 PUFA were found. Taken together, our data indicate that Aß1-42 might be crucially involved in behavioral alterations found after n-6 rich PUFA diet and strongly endorse the protective role of n-3 and the detrimental effect of improper n-6 PUFA diet consumption.

Early Loss of Blood-Brain Barrier Integrity Precedes NOX2 Elevation in the Prefrontal Cortex of an Animal Model of Psychosis.

The social isolation rearing of young adult rats is a model of psychosocial stress and provides a nonpharmacological tool to study alterations reminiscent of symptoms seen in psychosis. We have previously demonstrated that social isolation in rats leads to increased oxidative stress and to cerebral NOX2 elevations. Here, we investigated early alterations in mRNA expression leading to increased NOX2 in the brain. Rats were exposed to a short period of social isolation (1 week) and real-time polymerase chain reaction (PCR) for mRNA expression of genes involved in blood-brain barrier (BBB) formation and integrity (ORLs, Vof 21 and Vof 16, Leng8, Vnr1, and Trank 1 genes) was performed. Real-time PCR experiments, immunohistochemistry, and Western blotting analysis showed an increased expression of these genes and related proteins in isolated rats with respect to control animals. The expression of specific markers of BBB integrity, such as matrix metalloproteinase 2 (MMP2), matrix metalloproteinase 9 (MMP9), occludin 1, and plasmalemmal vesicle associated protein-1 (PV-1), was also significantly altered after 1 week of social isolation. BBB permeability, evaluated by quantification of Evans blue dye extravasation, as well as interstitial fluid, was significantly increased in rats isolated for 1 week with respect to controls. Isolation-induced BBB disruption was also accompanied by a significant increase of Interleukin 6 (IL-6) expression. Conversely, no differences in NOX2 levels were detected at this time point. Our study demonstrates that BBB disruption precedes NOX2 elevations in the brain. These results provide new insights in the interplay of mechanisms linking psychosocial stress to early oxidative stress in the brain, disruption of the BBB, and the development of mental disorders.

Toll-like receptor 4-dependent glial cell activation mediates the impairment in memory establishment induced by ß-amyloid oligomers in an acute mouse model of Alzheimer's disease.

BACKGROUND: Amyloid-ß oligomers (AßO) are species mainly involved in the synaptic and cognitive dysfunction in Alzheimer's disease. Although their action has been described mainly at neuronal level, it is now clear that glial cells govern synaptic activity in their resting state, contributing to new learning and memory establishment. In contrast, when activated, they may lead to synaptic and cognitive dysfunction. Using a reliable acute AßO-mediated mouse model of AD, we explored whether the memory alteration AßOs induce relies on the activation of glial cells, and if Toll-like receptor 4 (TLR4), pivotal in the initiation of an immune response, is involved. METHODS: C57 naïve mice were given a single intracerebroventricular injection of synthetic AßO-containing solution (1µM), which induces substantial impairment in the establishment of recognition memory. Then, first we assessed glial cell activation at different times post-injection by western blot, immunohistochemistry and ELISA in the hippocampus. After that we explored the efficacy of pre-treatment with anti-inflammatory drugs (indomethacin and an IL-1ß receptor antagonist) to prevent impairment in the novel object recognition task, and compared AßO's effects in TLR4 knockout mice. RESULTS: A single AßO injection rapidly activated glial cells and increased pro-inflammatory cytokine expression. Both anti-inflammatory drugs prevented the AßO-mediated impairment in memory establishment. A selective TLR4 receptor antagonist abolished AßO's action on memory, and in TLR4 knockout mice it had no effect on either memory or glial activation. CONCLUSIONS: These data provide new information on AßO's mechanism of action, indicating that besides direct action at the synapses, they also act through the immune system, with TLR4 playing a major role. This suggests that in a potential therapeutic setting inflammation must be considered as well.

Chlorella sorokiniana Extract Improves Short-Term Memory in Rats.

Increasing evidence shows that eukaryotic microalgae and, in particular, the green microalga Chlorella, can be used as natural sources to obtain a whole variety of compounds, such as omega (ω)-3 and ω-6 polyunsatured fatty acids (PUFAs). Although either beneficial or toxic effects of Chlorella sorokiniana have been mainly attributed to its specific ω-3 and ω-6 PUFAs content, the underlying molecular pathways remain to be elucidated yet. Here, we investigate the effects of an acute oral administration of a lipid extract of Chlorella sorokiniana, containing mainly ω-3 and ω-6 PUFAs, on cognitive, emotional and social behaviour in rats, analysing possible underlying neurochemical alterations. Our results showed improved short-term memory in Chlorella sorokiniana-treated rats compared to controls, without any differences in exploratory performance, locomotor activity, anxiety profile and depressive-like behaviour. On the other hand, while the social behaviour of Chlorella sorokiniana-treated animals was significantly decreased, no effects on aggressivity were observed. Neurochemical investigations showed region-specific effects, consisting in an elevation of noradrenaline (NA) and serotonin (5-HT) content in hippocampus, but not in the prefrontal cortex and striatum. In conclusion, our results point towards a beneficial effect of Chlorella sorokiniana extract on short-term memory, but also highlight the need of caution in the use of this natural supplement due to its possible masked toxic effects.

Chronic Psychosocial Stress Impairs Bone Homeostasis: A Study in the Social Isolation Reared Rat.

Chronic psychosocial stress is a key player in the onset and aggravation of mental diseases, including psychosis. Although a strong association between this psychiatric condition and other medical co-morbidities has been recently demonstrated, few data on the link between psychosis and bone homeostasis are actually available. The aim of this study was to investigate whether chronic psychosocial stress induced by 4 or 7 weeks of social isolation in drug-naïve male Wistar rats could alter bone homeostasis in terms of bone thickness, mineral density and content, as well as markers of bone formation and resorption (sclerostin, cathepsin K, and CTX-I). We found that bone mineral density was increased in rats exposed to 7 weeks of social isolation, while no differences were detected in bone mineral content and area. Moreover, 7 weeks of social isolation lead to increase of femur thickness with respect to controls, suggesting the development of a hyperostosis condition. Isolated rats showed no changes in sclerostin levels, a marker of bone formation, compared to grouped animals. Conversely, bone resorption markers were significantly altered after 7 weeks of social isolation in terms of decrease in cathepsin K and increase of CTX-I. No alterations were found after 4 weeks of isolation rearing. Our observations suggest that chronic psychosocial stress might affect bone homeostasis, more likely independently from drug treatment. Thus, the social isolation model might help to identify possible new therapeutic targets to treat the burden of chronic psychosocial stress and to attempt alternative therapy choices.

The role of the NADPH oxidase derived brain oxidative stress in the cocaine-related death associated with excited delirium: A literature review.

Excited delirium syndrome (ExDS) is a term used to describe a clinical condition characterized by bizarre and aggressive behaviour, commonly associated with the use of psychoactive compounds, especially cocaine. The pathophysiology of ExDS is complex and not yet fully understood. In addition to a central dopamine hypothesis, other mechanisms are thought to be involved in cocaine-related ExDS, such as increased reactive oxygen species production by the family of the NADPH oxidase NOX enzymes. In this review, we will summarize current knowledge on the crucial contribution of brain NADPH oxidase derived oxidative stress in the development of cocaine-induced ExDS. Data from animal models as well as human evidence will be discussed.

Soluble beta amyloid evokes alteration in brain norepinephrine levels: role of nitric oxide and interleukin-1.

Strong evidence showed neurotoxic properties of beta amyloid (Aß) and its pivotal role in the Alzheimer's disease (AD) pathogenesis. Beside, experimental data suggest that Aß may have physiological roles considering that such soluble peptide is produced and secreted during normal cellular activity. There is now suggestive evidence that neurodegenerative conditions, like AD, involve nitric oxide (NO) in their pathogenesis. Nitric oxide also possess potent neuromodulatory actions in brain regions, such as prefrontal cortex (PFC), hippocampus (HIPP), and nucleus accumbens (NAC). In the present study, we evaluated the effect of acute Aß injection on norepinephrine (NE) content before and after pharmacological manipulations of nitrergic system in above mentioned areas. Moreover, effects of the peptide on NOS activity were evaluated. Our data showed that 2 h after i.c.v. soluble Aß administration, NE concentrations were significantly increased in the considered areas along with increased iNOS activity. Pre-treatment with NOS inhibitors, 7-Nitroindazole (7-NI), and N6-(1-iminoethyl)-L-lysine-dihydrochloride (L-NIL), reversed Aß-induced changes. Ultimately, pharmacological block of interleukin1 (IL-1) receptors prevented NE increase in all brain regions. Taken together our findings suggest that NO and IL-1 are critically involved in regional noradrenergic alterations induced by soluble Aß injection.

Effects of anabolic-androgens on brain reward function.

Androgens are mainly prescribed to treat several diseases caused by testosterone deficiency. However, athletes try to promote muscle growth by manipulating testosterone levels or assuming androgen anabolic steroids (AAS). These substances were originally synthesized to obtain anabolic effects greater than testosterone. Although AAS are rarely prescribed compared to testosterone, their off-label utilization is very wide. Furthermore, combinations of different steroids and doses generally higher than those used in therapy are common. Symptoms of the chronic use of supra-therapeutic doses of AAS include anxiety, depression, aggression, paranoia, distractibility, confusion, amnesia. Interestingly, some studies have shown that AAS elicited electroencephalographic changes similar to those observed with amphetamine abuse. The frequency of side effects is higher among AAS abusers, with psychiatric complications such as labile mood, lack of impulse control and high violence. On the other hand, AAS addiction studies are complex because data collection is very difficult due to the subjects' reticence and can be biased by many variables, including physical exercise, that alter the reward system. Moreover, it has been reported that AAS may imbalance neurotransmitter systems involved in the reward process, leading to increased sensitivity toward opioid narcotics and central stimulants. The goal of this article is to review the literature on steroid abuse and changes to the reward system in preclinical and clinical studies.

Early life and oxidative stress in psychiatric disorders: what can we learn from animal models?

Schizophrenia is a complex pathology characterized by the occurrence of a variety of symptoms classified as positive, negative and cognitive. Although the exact etiopathogenesis of this disorder has not been unraveled yet, many theories have been endorsed during the last years. Among these, the neurochemical theories have been the most suited, considering the dopaminergic and glutamatergic dysfunctions to be mainly responsible for psychotic symptoms. However, the lack of efficacy of the available drugs, namely antipsychotics, toward negative and cognitive symptoms led to hypothesize alternative approaches. In this regard, the neurodevelopmental theory of schizophrenia has emerged, proposing the association between the occurrence of environmental risk factors in early-life and the development of psychosis in late-life. In particular, exposure to early life stressing situations, such as pre- and peri-natal stress, has been suggested as a risk factor to d evelop psychopathologies in adulthood in people genetically predisposed. A crucial support in favor of this hypothesis came from neurodevelopmental animal models of schizophrenia, such as maternal malnutrition, maternal deprivation, maternal infections as well as post-weaning social isolation rearing. Moreover, data from these models, corroborated by clinical findings, indicate that oxidative and nitrosative stress play a crucial role in the etiopathogenesis of psychiatric disorders. In the present work, we reviewed the recent progress in literature regarding data available from animal models linking oxidative and nitrosative stress to psychiatric disorders in order to evaluate novel biomarkers of pathology as well as novel therapeutical targets.

Memantine prevents memory consolidation failure induced by soluble beta amyloid in rats.

It has been well documented that ß-amyloid (Aß) peptide accumulation and aggregation in the brain plays a crucial role in the pathophysiology of Alzheimer's disease (AD). However, a new orientation of the amyloid cascade hypothesis has evidenced that soluble forms of the peptide (sAß) are involved in Aß-induced cognitive impairment and cause rapid disruption of the synaptic mechanisms underlying memory. The primary aim of this study was to elucidate the effects of sAß, acutely injected intracerebrally (i.c.v., 4 µM), on the short term and long term memory of young adult male rats, by using the novel object recognition task. Glutamatergic receptors have been proposed as mediating the effect of Aß on synaptic plasticity and memory. Thus, we also investigated the effects of sAß on prefrontal cortex (PFC) glutamate release and the specific contribution of N-methyl-D-aspartate (NMDA) receptor modulation to the effects of sAß administration on the cognitive parameters evaluated. We found that a single i.c.v. injection of sAß 2 h before testing did not alter the ability of rats to differentiate between a familiar and a novel object, in a short term memory test, while it was able to negatively affect consolidation/retrieval of long term memory. Moreover, a significant increase of glutamate levels was found in PFC of rats treated with the peptide 2 h earlier. Interestingly, memory deficit induced by sAß was reversed by a NMDA-receptor antagonist, memantine (5 mg/kg i.p), administered immediately after the familiarization trial (T1). On the contrary, memantine administered 30 min before T1 trial, was not able to rescue long term memory impairment. Taken together, our results suggest that an acute i.c.v. injection of sAß peptide interferes with the consolidation/retrieval of long term memory. Moreover, such sAß-induced effect indicates the involvement of glutamatergic system, proposing that NMDA receptor inhibition might prevent or lead to the recovery of early cognitive impairment.