RESUMO
STUDY OBJECTIVES: To determine whether an intensive weight-loss program (IWLP) is effective for reducing weight, the severity of obstructive sleep apnea (OSA), and metabolic variables in patients with obesity and severe OSA undergoing continuous positive airway pressure treatment. METHODS: Forty-two patients were randomized to the control (CG, n = 20) or the intervention group (IG, n = 22), who followed a 12-month IWLP. The primary outcome was a reduction in the apnea-hypopnea index (AHI) as measured at 3 and 12 months by full polysomnography. Metabolic variables, blood pressure, body fat composition by bioimpedance, carotid intima media thickness, and visceral fat by computed tomography were also assessed. RESULTS: Mean age was 49 (6.7) years, body mass index 35 (2.7) kg/m², and AHI 69 (20) events/h. Weight reduction was higher for the IG than the CG at 3 and 12 months, -10.5 versus -2.3 kg (P < .001), and -8.2 versus -0.1 kg (P < .001), respectively, as was loss of visceral fat at 12 months. AHI decreased more in the IG at 3 months (-23.72 versus -9 events/h) but the difference was not significant at 12 months, though 28% of patients from the IG had an AHI < 30 events/h compared to none in the CG (P = .046). At 12 months, the IG showed a reduction in C-reactive protein (P = .013), glycated hemoglobin (P = .031) and an increase in high density lipoprotein cholesterol (P = .027). CONCLUSIONS: An IWLP in patients with obesity and severe OSA is effective for reducing weight and OSA severity. It also results in an improvement in lipid profiles, glycemic control, and inflammatory markers. CLINICAL TRIAL REGISTRATION: Registry: ClinicalTrials.gov; Title: Effectiveness of an Intensive Weight Loss Program for Obstructive Sleep Apnea Syndrome (OSAS) Treatment; Identifier: NCT02832414; URL: https://clinicaltrials.gov/ct2/show/record/NCT02832414.
Assuntos
Apneia Obstrutiva do Sono , Programas de Redução de Peso , Espessura Intima-Media Carotídea , Pressão Positiva Contínua nas Vias Aéreas , Humanos , Pessoa de Meia-Idade , Polissonografia , Apneia Obstrutiva do Sono/complicações , Apneia Obstrutiva do Sono/terapia , Resultado do TratamentoRESUMO
Endogenous cannabinoids, through the CB1 receptor, are involved in the control of several functions including stress responses. The aim of this study was to investigate the presence of cannabinoid receptor CB1 in the sole ovary by partial cloning of brain CB1 cDNA; in a stress paradigm of disturbance by handling, which consisted in catching, netting and hand-sorting, changes of CB1 mRNA were related with those of proopiomelanocortin (POMC) mRNA; the trend and timing of stress responses and adaptation were monitored by measuring plasma cortisol levels. We characterized two forms of CB1-like receptor, termed CB1A and CB1B. The two sole CB1 (both 799bp) share 76% identity in their cDNAs, and the deduced amino acid sequences are 80% identical. The handling stress induced a sustained increase in plasma cortisol levels 1h after the handling began and decreased to low levels 12h after initiation of handling, showing the same trend of ovarian POMC mRNA expression. In addition, while CB1A mRNA did not show any significant changes during handling stress, significantly lower levels of CB1B mRNA were found in stressed fish 1h after the beginning of handling, with CB1 expression increased 24h after stress induction, both in the ovary and brain. It can be concluded that endocannabinoid system is involved in the modulation of adaptive responses to environmental conditions.
Assuntos
DNA Complementar/genética , Linguados/genética , Receptor CB1 de Canabinoide/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Clonagem Molecular , Feminino , Regulação da Expressão Gênica , Hidrocortisona/sangue , Dados de Sequência Molecular , Ovário/metabolismo , Pró-Opiomelanocortina/genética , Pró-Opiomelanocortina/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptor CB1 de Canabinoide/química , Receptor CB1 de Canabinoide/metabolismo , Análise de Sequência de DNA , Homologia de Sequência de AminoácidosRESUMO
A quantitative study of the kinetics of electron transfer under coupled conditions in photosynthetic bacteria has so far been prevented by overlap of the electrochromic signals of carotenoids and bacteriochlorophyll with the absorbance changes of cytochromes and reaction centers. In this paper a method is presented by which the electrochromic contribution at any wavelength can be calculated from the electrochromic signal recorded at 505 nm, using a set of empirically determined polynomial functions. The electrochromic contribution to kinetic changes at any wavelength can then be subtracted to leave the true kinetics of the redox changes. The corrected redox changes of the reaction center measured at 542 and 605 nm mutually agree, thus providing an excellent test of self-consistency of the method. The corrected traces for reaction center and of cytochrome b-566 demonstrate large effects of the membrane potential on the rate and poise of electron transfer. It will be possible to study the interrelation between proton gradient and individual electron reactions under flash or steady-state illumination.
Assuntos
Cromatóforos Bacterianos/metabolismo , Rodopseudomonas/metabolismo , Cromatóforos Bacterianos/efeitos dos fármacos , Grupo dos Citocromos b/metabolismo , Escuridão , Transporte de Elétrons , Cinética , Luz , Oxirredução , Fotossíntese , Valinomicina/farmacologiaRESUMO
Rats with different degrees of microencephaly were obtained by injecting pregnant mothers with methylazoxymethanol acetate (MAM) at gestational days 13.5 or 16.5. Specific markers for cholinergic (choline acetyltransferase, ChAT), GABAergic (glutamate decarboxylase, GAD), and glutamatergic (D-3H aspartate high affinity uptake) neurons, were measured in several brain regions (cortex, hippocampus, anterior and posterior striatum, medial septum plus nucleus of the diagonal band, globus pallidus) in young and adult microencephalic rats. In adult rats born to mothers injected with MAM at gestational day 16.5 (G16.5) ChAT level was increased in the cortex, hippocampus and striatum but decreased in the septal complex; GAD was decreased in the globus pallidus and, to a little extent, in the hippocampus while D-3H aspartate uptake was decreased in the striatum. One month old rats belonging to the same group showed comparable differences with the exception of larger increase of ChAT in the cortex and striatum. In adult rats born from mothers injected with MAM at gestational day 13.5 (G13.5) differences in the cholinergic marker were in general less pronounced; GAD was not decreased in the globus pallidus and D-3H aspartate uptake was unchanged in the striatum but significantly decreased in the hippocampus. The results are correlated with morphological brain alterations caused by differentially timed MAM treatment and with available information on the generation time of various neuronal populations. They show that the balance between different neurotransmitter systems can be experimentally altered and suggest that MAM treatment may provide an experimental tool for studying the development of this balance.
RESUMO
Systemic administration of kainic acid results in the development of a characteristic convulsive syndrome, accompanied by neuropathological alterations and loss of transmitter markers in some forebrain regions. Since some of these effects appear to involve the N-methyl-D-aspartate (NMDA) subtype of excitatory amino acid receptors, the protection given by a non-competitive (MK-801) and a competitive (CGP 39551) NMDA receptor antagonist against the loss of glutamatergic and gamma-amino butyric acid (GABAergic) neurochemical markers was compared. Appropriate doses of both compounds (1 mg/kg MK-801 and 25 mg/kg CGP 39551) completely reversed the decrease of high affinity uptake of glutamate and activity of glutamate decarboxylase in the olfactory cortex, amygdala, hippocampus and lateral septum. In addition, they also essentially counteracted the increase of a glial marker, the enzyme glutamine synthetase, consequent to neuronal degeneration. The results confirmed that involvement of NMDA receptors is essential for the full expression of neuropathological effects of kainic acid. They also support the use of a competitive antagonist of the NMDA receptor, such as CGP 39551, to afford substantial protection against the excitotoxic damage, whilst giving fewer side effects and motor disturbances than MK-801.
Assuntos
2-Amino-5-fosfonovalerato/análogos & derivados , Maleato de Dizocilpina/farmacologia , Epilepsia/prevenção & controle , Ácido Caínico/antagonistas & inibidores , Neurotransmissores/metabolismo , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , 2-Amino-5-fosfonovalerato/farmacologia , Animais , Epilepsia/induzido quimicamente , Epilepsia/patologia , Masculino , Neuroglia/efeitos dos fármacos , Ratos , Ratos Endogâmicos , SíndromeRESUMO
Release of both D-[3H]aspartate and endogenous amino acids was measured in primary cultures of cerebellar granule cells. Two hour-pretreatment with the glycosphingolipids, GM1 or GT1b, attenuated the stimulation of excitatory amino acid release induced by depolarizing concentrations of K+ (50 mM). Gangliosides inhibited the phencyclidine (PCP)-sensitive component of depolarization-induced release, i.e. the amplification of release that follows activation of NMDA receptors by the endogenous glutamate.
Assuntos
Aminoácidos/metabolismo , Cerebelo/metabolismo , Gangliosídeos/farmacologia , Neurônios/metabolismo , Receptores de Neurotransmissores/fisiologia , Animais , Ácido Aspártico/metabolismo , Cerebelo/citologia , Cerebelo/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão , Glutamatos/metabolismo , Neurônios/efeitos dos fármacos , Fenciclidina/farmacologia , Cloreto de Potássio/farmacologia , Ratos , Receptores de N-Metil-D-Aspartato , Acetato de Tetradecanoilforbol/farmacologiaRESUMO
A competitive antagonist of the N-methyl-D-aspartate receptor, CGP 39551, was administered daily to neonatal rats with increasing doses from postnatal day 1 to 22. These animals displayed approximately 50% decrease of body weight at the end of treatment and, therefore, both normal and neonatally undernourished rats were used as controls. At a young adult stage (55-75 days of age) CGP 39551-treated rats showed a much higher spontaneous locomotor activity as compared to control groups. This hypermotility was counteracted by D1 and D2 dopamine antagonists while administration of methamphetamine increased, to the same extent, the differential basal locomotor activity of treated and control groups. The locomotor activity response to the N-methyl-D-aspartate channel blocker, dizocilpine maleate, was significantly shifted to the right for treated rats so that an equivalent increase of motility was obtained by doubling the dose effective for control animals. In in vivo microdialysis experiments, similar amounts of dopamine were collected from the striatum of treated and control rats after high K+ or methamphetamine stimulation, the only difference being a greater Ca2+ dependency of the depolarization-induced dopamine release in treated rats. Assays for different neurochemical parameters, carried out at 80-90 days of age, suggested some alteration of the balance between excitatory and inhibitory circuits in the basal ganglia of CGP 39551-treated rats. Tyrosine hydroxylase and calbindin immunostaining, as well as acetylcholinesterase histochemistry, revealed a similar picture in the striatum of treated and control rats. However, 5'-nucleotidase histochemistry showed a stronger and evenly distributed reactivity in the striatum of treated rats, opposite to the weaker and patchy localization of normal or undernourished controls. From the present results it is possible to conclude that chronic blockade of the N-methyl-D-aspartate receptor during neonatal brain maturation results in long-lasting alteration of locomotor activity which appears related to functional changes of the dopamine receptors as well as to an altered balance between various excitatory and inhibitory neurotransmitter and neuromodulatory systems.
Assuntos
2-Amino-5-fosfonovalerato/análogos & derivados , Envelhecimento/fisiologia , Corpo Estriado/metabolismo , Atividade Motora/efeitos dos fármacos , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , 2',3'-Nucleotídeo Cíclico Fosfodiesterases/metabolismo , 2-Amino-5-fosfonovalerato/administração & dosagem , 2-Amino-5-fosfonovalerato/farmacologia , Animais , Animais Recém-Nascidos , Ácido Aspártico/metabolismo , Benzamidas/farmacologia , Benzazepinas/farmacologia , Colina O-Acetiltransferase/metabolismo , Corpo Estriado/efeitos dos fármacos , Maleato de Dizocilpina/farmacologia , Dopamina/metabolismo , Antagonistas dos Receptores de Dopamina D2 , Relação Dose-Resposta a Droga , Esquema de Medicação , Glutamato Descarboxilase/metabolismo , Glutamato-Amônia Ligase/metabolismo , Distúrbios Nutricionais/metabolismo , Distúrbios Nutricionais/fisiopatologia , Ratos , Ratos Wistar , Receptores de Dopamina D1/antagonistas & inibidoresRESUMO
The excitotoxic brain damage caused by systemic administration of kainic acid requires the activation of N-methyl-D-aspartate (NMDA) receptors in order to fully express its neurotoxic potency. We have tested the relative efficacy of different manipulations of the NMDA receptor on morphological, immunohistochemical and neurochemical parameters in this experimental model. A competitive (CGP 39551) and a non-competitive (MK 801) antagonist of the NMDA receptor, granted full protection against neuronal degeneration and consequent glial proliferation in the hippocampus and olfactory cortex, two regions severely affected by systemic administration of kainic acid. In addition, CGP 39551 completely counteracted the dramatic induction of the enzyme ornithine decarboxylase which occurs shortly after kainic acid administration. Systemic administration of high amounts of MgSO4 concomitantly and after kainic acid injection, appeared to partially prevent neuronal degeneration but had no clear effects on glial reaction and ornithine decarboxylase induction. Finally administration of an antagonist of the polyamine site present in the NMDA receptor (SL 82.0715), did not appear to have any protective effect at the dose used here. The present results help to better understand the ways by which it could be possible to counteract excitotoxic brain injuries.
RESUMO
The toxicity of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, intravitreally injected in goldfish eye, involves interplexiform retinal neurons and depletes tyrosine hydroxylase immunoreactivity and dopamine levels. This induced neurotoxicity was prevented by the concomitant administration in non-toxic doses (10 micrograms) of quinolinic acid, an endogenous structural analogue of N-methyl D-aspartate with excitotoxic properties. Quinolinic acid is ineffective on the retinal degeneration induced by 1-methyl-4-phenylpyridinium ion. This fact suggests that quinolinic acid inhibits the MAO-B oxidation of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. MK-801, a noncompetitive antagonist of glutamate NMDA-receptors, exerts partial protective effects on MPTP-induced delayed toxicity in mammals. In the goldfish eye, MK-801, injected in low concentration, and in conjunction with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine or 1-methyl-4-phenylpyridinium ion, did not prevent retinal neurodegeneration. Ten micrograms of MK-801 alone did not affect retinal neurons, while a higher concentration (20 micrograms) causes the chromatolysis of some photoreceptor nuclei.
Assuntos
Maleato de Dizocilpina/farmacologia , Dopamina/metabolismo , Intoxicação por MPTP , Neurônios/patologia , Ácido Quinolínico/farmacologia , Retina/patologia , 1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina/antagonistas & inibidores , 1-Metil-4-fenilpiridínio/farmacologia , Animais , Cromatografia Líquida de Alta Pressão , Carpa Dourada , Microscopia Eletrônica , Necrose , Neurônios/efeitos dos fármacos , Neurônios/ultraestrutura , Células Fotorreceptoras/efeitos dos fármacos , Células Fotorreceptoras/patologia , Células Fotorreceptoras/ultraestrutura , Retina/efeitos dos fármacosRESUMO
Neonatal rats were subjected to chronic blockade of the N-methyl-D-aspartate (NMDA) receptor through daily systemic administration of increasing doses of the competitive antagonist CGP 39551 from postnatal days 1-22. Treatment did not result in any significant alteration of the levels of putrescine, spermidine and spermine or in the constitutively expressed activity of the key enzyme for polyamine biosynthesis, ornithine decarboxylase (ODC), as evaluated at 10 and 20 days of age. However, in 30-day-old rats significant differences were observed in the process of excitotoxic ODC induction in the olfactory cortex and the hippocampus of chronically-treated rats: the increase of ODC activity caused by systemic administration of kainic acid took place more rapidly but it was shorter and apparently reached a smaller peak in treated animals as compared to controls. This result, in conjunction with previous data on neurochemistry and locomotor activity of similarly treated rats, strengthens the suggestion that functional alterations of some brain circuits may be the consequence of the blockade of NMDA receptor during the critical neonatal period of brain maturation.
Assuntos
2-Amino-5-fosfonovalerato/análogos & derivados , Envelhecimento/metabolismo , Encéfalo/metabolismo , Ornitina Descarboxilase/biossíntese , Poliaminas/metabolismo , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , 2-Amino-5-fosfonovalerato/farmacologia , Animais , Animais Recém-Nascidos , Encéfalo/efeitos dos fármacos , Encéfalo/crescimento & desenvolvimento , Cerebelo/efeitos dos fármacos , Cerebelo/metabolismo , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Indução Enzimática , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Putrescina/metabolismo , Ratos , Ratos Wistar , Valores de Referência , Espermidina/metabolismo , Espermina/metabolismo , Telencéfalo/efeitos dos fármacos , Telencéfalo/metabolismoRESUMO
Kainic acid, a powerful neuroexcitant and neurotoxin, stimulates the release of naturally occurring excitatory amino acids, l-glutamate and l-aspartate, from hippocampal synaptosomes. The release stimulation affects in a similar way both the general pool of the two amino acids and the fraction of l-glutamate and l-aspartate, newly-synthetized from precursors or recently accumulated through the high-affinity uptake mechanism. Kainic acid exerts its stimulatory action on the basal release of the two amino acids as well as on the high K(+)-stimulated release of l-glutamate. Kainic acid has, however, different effects on the release of exogenously accumulated [d-(3)H]aspartate. In particular, the high K(+)-stimulated release of this false transmitter is strongly inhibited by 1 mM kainic acid. The present data confirm the presynaptic action of kainic acid on the general as well as on the recently-formed pools of naturally occurring excitatory amino acids. At the same time, our results suggest that [d-(3)H]aspartate is not a reliable substitute for l-glutamate and l-aspartate, in release studies and that the radioactivity released after preloading with [d-(3)H]aspartate does not necessarily reflect the release of naturally occurring excitatory amino acids.
RESUMO
Xanthine dehydrogenase and oxidase activities increased by 87% in rat brain slices after 30 min in vitro ischaemia. A further 41% increase was induced by 30 min simulated reperfusion of ischaemic slices. No conversion from the dehydrogenase to the oxidase activity was observed. The increment of enzyme activity was not due to neosynthesis of the enzyme, since it was not affected by the addition of cycloheximide during the ischaemic incubation. The increased oxygen-dependent form of the enzyme could aggravate the ischaemic brain injury by free radicals production, in particular after reperfusion.
Assuntos
Encéfalo/enzimologia , Ataque Isquêmico Transitório/enzimologia , Modelos Biológicos , Reperfusão , Xantina Desidrogenase/metabolismo , Xantina Oxidase/metabolismo , Animais , Cicloeximida/farmacologia , Técnicas In Vitro , Masculino , Oxigênio/farmacologia , Inibidores da Síntese de Proteínas/farmacologia , Ratos , Ratos Wistar , Traumatismo por ReperfusãoRESUMO
Rat pups were treated daily with increasing doses of the competitive N-methyl-D-aspartate (NMDA) antagonist CGP 39551 from postnatal day 1 to 22. Normal rats, as well as rats kept undernourished to the same extent as CGP 39551-treated animals were raised in parallel. The neonatal treatment resulted in significant increase of choline acetyltransferase (+14%) in the adult spinal cord. High affinity glutamate uptake was increased to a similar magnitude in treated rats, but the same effect was also noticed for neonatally undernourished rats. No alteration of other neurochemical markers was observed. The present results add new evidence to a developmental role mediated by NMDA receptors and extend to the spinal cord the value of models of chronic neonatal block of this receptor.
Assuntos
2-Amino-5-fosfonovalerato/análogos & derivados , Acetilcolina/metabolismo , Neurônios/efeitos dos fármacos , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Medula Espinal/efeitos dos fármacos , 2-Amino-5-fosfonovalerato/farmacologia , Análise de Variância , Animais , Animais Recém-Nascidos , Biomarcadores/química , Neurônios/metabolismo , Ratos , Ratos Wistar , Medula Espinal/citologia , Medula Espinal/metabolismo , Fatores de TempoRESUMO
Neonatal rats were daily treated with increasing doses of the competitive NMDA antagonist CGP 39551 from postnatal day 1 to 22. At 75-80 days of age the rats were given an excitotoxic dose of kainic acid s.c. Histological examination suggested that the olfactory cortex of the neonatally CGP 39551-treated rats was less damaged than that of controls. This was quantitatively confirmed by assaying the decrease of appropriate neurochemical markers (D-[3H]aspartate uptake and glutamate decarboxylase) as an index of the extent of neuronal degeneration. By contrast, the decrease of the same markers was not different in the hippocampus. These results suggest a selective effect on some brain circuits of adult rats consequent to the neonatal blockade of NMDA receptors and, therefore, add new evidence to a developmental role of this receptor.
Assuntos
2-Amino-5-fosfonovalerato/análogos & derivados , Ácido Caínico/farmacologia , Degeneração Neural/efeitos dos fármacos , Bulbo Olfatório/efeitos dos fármacos , Ornitina Descarboxilase/biossíntese , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , 2-Amino-5-fosfonovalerato/farmacologia , Análise de Variância , Animais , Animais Recém-Nascidos , Indução Enzimática , Hipocampo/efeitos dos fármacos , Hipocampo/crescimento & desenvolvimento , Bulbo Olfatório/crescimento & desenvolvimento , Ratos , Ratos WistarRESUMO
The density of binding sites for kainic acid was measured both in fresh slices and in the particulate fraction of the homogenate from various zones of the CNS of goldfish. Binding in the homogenate fraction was always found higher than in the corresponding slices, which should be representative of receptors located on the outer surface of the cellular membrane. The hypothesis is discussed that the sites demonstrated by homogenization are located in the intracellular compartment.
Assuntos
Sistema Nervoso Central/metabolismo , Cyprinidae/metabolismo , Carpa Dourada/metabolismo , Membranas Intracelulares/metabolismo , Receptores de Neurotransmissores/metabolismo , Animais , Sítios de Ligação , Ácido Caínico/metabolismo , Receptores de Ácido Caínico , Distribuição Tecidual , TrítioRESUMO
Methylazoxymethanol acetate (MAM) was injected to female rats at the beginning of the 17th day of gestation. Resulting offspring showed a remarkable decrease in the size of the medial habenula while the interpeduncular nucleus, whose neurons are generated before the time of MAM treatment, appeared anatomically unaffected. Choline acetyltransferase was significantly reduced in the habenulae and in the interpeduncular nucleus suggesting that MAM treatment had depleted a portion of the cholinergic neurons of the medial habenula which project to the interpeduncular nucleus. Aromatic amino acid decarboxylase significantly increased in the interpeduncular nucleus, a likely effect of monoaminergic hyperinnervation in response to partial cholinergic deprivation. MAM strategy can be usefully adopted for the study of general aspects of brain development when connected nuclei showing no overlapping in neuronal generation times are involved.
Assuntos
Acetilcolinesterase/metabolismo , Descarboxilases de Aminoácido-L-Aromático/metabolismo , Compostos Azo/toxicidade , Encéfalo/embriologia , Colina O-Acetiltransferase/metabolismo , Glutamato Descarboxilase/metabolismo , Acetato de Metilazoximetanol/toxicidade , Neurônios/citologia , Tálamo/embriologia , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/patologia , Feminino , Troca Materno-Fetal , Neurônios/efeitos dos fármacos , Neurônios/enzimologia , Gravidez , Ratos , Ratos Endogâmicos , Valores de Referência , Tálamo/efeitos dos fármacos , Tálamo/patologiaRESUMO
Overstimulation of the NMDA receptor, as well as generation of excessive amounts of free radicals, has been implicated in excitotoxic brain injuries. We report here that two antagonists of the NMDA receptor and an inhibitor of the free radical-generating enzyme, xanthine oxidase, protect the olfactory cortex but not the striatum after intrastriatal injection of kainic acid. Our results suggest the existence of a precise link between excitotoxic activation of the NMDA receptor and neuropathology related to excessive amounts of free radicals. The focal point of this link may be the entry of Ca2+ through the NMDA receptor and the consequent activation of proteases and free radical-generating systems.
Assuntos
Alopurinol/farmacologia , Córtex Cerebral/efeitos dos fármacos , Corpo Estriado/efeitos dos fármacos , Ácido Caínico/farmacologia , Condutos Olfatórios/efeitos dos fármacos , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Animais , Morte Celular/efeitos dos fármacos , Córtex Cerebral/citologia , Colina O-Acetiltransferase/metabolismo , Corpo Estriado/citologia , Corpo Estriado/metabolismo , Glutamato Descarboxilase/metabolismo , Injeções , Masculino , Neurônios/efeitos dos fármacos , Ratos , Ratos EndogâmicosRESUMO
Young adult rats were chronically treated with lithium (2.5 mmol/kg/day) for 16 days. The day after the last lithium administration, rats were injected s.c. with the excitotoxic convulsant kainic acid (10 mg/kg). As compared to saline controls, lithium-treated rats had no apparent attenuation of convulsions. Furthermore, the induction of brain ornithine decarboxylase and the consequent increase of putrescine levels, an index related to the convulsant effects of kainic acid, were similar in saline- and lithium-treated rats. Other rats were unilaterally injected with ibotenic acid into the nucleus basalis magnocellularis: no differences were measured in cortical choline acetyltransferase (ChAT) decrease among saline- and lithium-treated rats. In both the above experiments, apoptotic cell death was monitored in relevant brain regions of saline- or lithium-treated rats through a specific in situ labeling method for fragmented DNA. Whilst morphological evidence for a reduced damage in the olfactory cortex and hippocampus of kainic acid-injected rats was not obtained, lithium-treated rats showed a lower decrease of specific neurochemical markers: [3H]D-aspartate uptake and glutamate decarboxylase. This result suggests that mechanisms of recovery, absent in saline-treated animals, are elicited by the excitotoxic insult in lithium-treated rats.
Assuntos
Encéfalo/patologia , Aminoácidos Excitatórios/toxicidade , Lítio/farmacologia , Ornitina Descarboxilase/biossíntese , Animais , Apoptose/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Química Encefálica/efeitos dos fármacos , Agonistas de Aminoácidos Excitatórios/administração & dosagem , Agonistas de Aminoácidos Excitatórios/toxicidade , Aminoácidos Excitatórios/administração & dosagem , Histocitoquímica , Ácido Ibotênico/administração & dosagem , Ácido Ibotênico/toxicidade , Injeções , Ácido Caínico/administração & dosagem , Ácido Caínico/toxicidade , Sistema Nervoso Parassimpático , Prosencéfalo , Ratos , Ratos WistarRESUMO
Neuronal nitric oxide synthase (nNOS) and NADPH-diaphorase activities were investigated in discrete areas of the central nervous system of goldfish and brown trout. Both species showed a similar distribution pattern of nNOS activity with regional differences in all examined areas. Telencephalon and hypothalamus showed the highest nNOS values, while in the goldfish cerebellum and its valvula nNOS was not detectable. In both species, NADPH-diaphorase activity showed a lower regional variability, compared to nNOS. The highest activity was measured in the olfactory bulbs where, conversely, low levels of nNOS activity were present. The non close correspondence between NOS and NADPH-diaphorase activities confirms the discrepancies indicated by morphological data. Western blot analysis revealed the presence of a nNOS isoform of about 150 kDa mol. wt. corresponding to that of mammals. The pattern of nNOS expression in the considered brain regions of the goldfish and trout was comparable to the levels of the nNOS activity.
Assuntos
Sistema Nervoso Central/enzimologia , Carpa Dourada/metabolismo , NADPH Desidrogenase/metabolismo , Neurônios/enzimologia , Óxido Nítrico Sintase/metabolismo , Truta/metabolismo , Animais , Western Blotting , Sistema Nervoso Central/citologia , Carpa Dourada/anatomia & histologia , Histocitoquímica , Neurônios/citologia , Truta/anatomia & histologiaRESUMO
Microencephalic rats were obtained through gestational (for the forebrain) or neonatal (for the cerebellum) administration of the DNA-alkylating agent methylazoxymethanol acetate (MAM), which selectively kills dividing cells during neurogenesis. In the microencephalic cerebellum the specific activity of calcium-dependent nitric oxide synthase (NOS) was decreased by 35-40% at 12, 28 and 70 days of age. Other neurochemical markers not related to granule cells (the neuronal population selectively compromised by neonatal MAM treatment), choline acetyltransferase (ChAT) and glutamate decarboxylase (GAD) were not decreased, but actually increased when determined as specific activity. In agreement with the decreased catalytic activity measured in the tube, the expression of neuronal NOS protein was attenuated as judged from immunohistochemistry and Western blotting. In the microencephalic forebrain, the specific calcium-dependent NOS activity measured in homogenates of the whole hemisphere was significantly increased as compared to normal animals. Accordingly, immunohistochemistry for neuronal NOS, as well as NADPH-diaphorase histochemistry revealed an apparent increase in the density of strongly reactive neurons in the underdeveloped cortex and striatum of microencephalic rats. The results reported here demonstrate that permanent alterations of neuronal NOS activity and expression occur when the development of the brain and its neuronal circuits are severely compromised. Furthermore, the permanent downregulation of neuronal NOS in the cerebellum of microencephalic rats may be exploited for the study of the role of NO in mechanisms of synaptic plasticity such as long term depression (LTD).