RESUMO
1. Male Wistar rats were submitted to paradoxical sleep deprivation for 96 hr by a modified multiple platform technique. 2. Training of step-through inhibitory avoidance was performed immediately after the last day of paradoxical sleep deprivation. Twenty-four hr after training the animals were submitted to the retention test. 3. In Experiment 1, pilocarpine (4 mg/kg, i.p.) or atropine (4 mg/kg, i.p.) were administered daily during the paradoxical sleep deprivation period. Pilocarpine, but not atropine, reversed the impairment induced by PS deprivation. 4. In Experiment 2, pilocarpine (4, 8 and 12 mg/kg, i.p.) was injected 1 hr before training in order to verify if the reversal of memory impairment was an effect secondary to residual enhanced blood levels of pilocarpine during training. Acute treatment with pilocarpine, in any dose, did not reverse the impairment produced by paradoxical sleep deprivation 5. Activation of the cholinergic system during the period of deprivation is able to prevent memory deficits induced by paradoxical sleep deprivation.
Assuntos
Aprendizagem da Esquiva , Privação do Sono , Sono REM/fisiologia , Animais , Atropina/administração & dosagem , Atropina/farmacologia , Masculino , Agonistas Muscarínicos/administração & dosagem , Agonistas Muscarínicos/farmacologia , Antagonistas Muscarínicos/administração & dosagem , Antagonistas Muscarínicos/farmacologia , Pilocarpina/administração & dosagem , Pilocarpina/farmacologia , Ratos , Ratos Wistar , Receptores Colinérgicos/fisiologiaRESUMO
Recent findings from this laboratory revealed that sleep deprivation reduces total glutathione (GSH) levels in hypothalamus, suggesting an increased vulnerability to oxidative damage. Since melatonin has been shown to prevent oxidative damage in other experimental situations, the present study tested the effects of exogenous melatonin on sleep deprivation-induced GSH decreases. Rats were deprived of sleep for 96 h on small platforms, and melatonin (10 mg/kg body weight; i.p.) or vehicle was given twice a day. Hypothalamic GSH levels were significantly reduced in sleep-deprived groups, irrespective of melatonin treatment. Indeed, unexpectedly, melatonin treatment resulted in lower hypothalamic GSH levels in all groups, including cage controls. These results confirm that sleep deprivation reduces hypothalamic GSH and further indicate that melatonin treatment not only is ineffective in reversing this effect but may actually potentiate it.
Assuntos
Antioxidantes/farmacologia , Encéfalo/efeitos dos fármacos , Glutationa/efeitos dos fármacos , Melatonina/farmacologia , Privação do Sono/fisiopatologia , Animais , Encéfalo/metabolismo , Glutationa/metabolismo , Hipotálamo/efeitos dos fármacos , Hipotálamo/metabolismo , Masculino , Ratos , Ratos WistarRESUMO
Because stressful manipulations have been reported to modify drug-induced yawning, the present study investigated the effects of single and repeated treatment with a synthetic glucocorticoid, dexamethasone (DEXA) on apomorphine- and pilocarpine-induced yawning in male rats. Neither single nor repeated treatment with DEXA altered apomorphine-induced yawning. Single administration of DEXA, however, resulted in an increased number of yawns induced by pilocarpine. Conversely, repeated administration of DEXA led to a decreased number of yawns induced by pilocarpine. In conclusion, the present findings show that dopaminergic and cholinergic are distinctly altered by DEXA, in terms of yawning behavior when animals received DEXA.
Assuntos
Agonistas Colinérgicos/farmacologia , Dexametasona/farmacologia , Agonistas de Dopamina/farmacologia , Glucocorticoides/farmacologia , Bocejo/efeitos dos fármacos , Animais , Apomorfina/antagonistas & inibidores , Apomorfina/farmacologia , Masculino , Agonistas Muscarínicos/farmacologia , Pilocarpina/antagonistas & inibidores , Pilocarpina/farmacologia , Ratos , Ratos WistarRESUMO
The methods used to induce paradoxical sleep (PS) deprivation are believed to be stressful. In the present study, two methods were compared in regard to their ability to activate the hypothalamic-pituitary-adrenal (HPA) axis. Animals were placed on multiple large (MLP) or small (MSP) platforms or on single large (SLP) or small (SSP) platforms and blood sampled at the end of a 4-day period of PS deprivation (experiment 1) or on Days 1 (short-term) and 4 (long-term) of PS deprivation (experiment 2). ACTH and corticosterone (CORT) levels were determined by RIA. The results of experiment 1 showed that all experimental animals presented increased ACTH response, compared to controls. CORT levels, however, were only elevated in MSP animals, suggesting increased adrenal sensitivity. Experiment 2 showed that ACTH levels of MSP animals were higher than MLP and SSP animals, and that animals placed on the multiple platform tanks showed the highest ACTH levels on Day 4 of manipulation. CORT levels were elevated in the animals kept over small platforms, and these levels where higher on Day 1 than basal and further elevated on Day 4 of PS deprivation. These results indicate that the multiple platform technique induces a distinct activation of the HPA axis, and that PS deprivation may act as an additional stressor.
Assuntos
Hormônio Adrenocorticotrópico/metabolismo , Corticosterona/metabolismo , Sistema Hipotálamo-Hipofisário/metabolismo , Sistema Hipófise-Suprarrenal/metabolismo , Privação do Sono/fisiologia , Sono REM/fisiologia , Animais , Masculino , Ratos , Ratos Wistar , Fatores de TempoRESUMO
Rats were deprived of sleep for 96 h by the platform technique and total glutathione (GSHtau) levels were measured in seven different brain areas. Glutathione levels were found to be significantly reduced in the hypothalamus of sleep-deprived animals when compared with large platform (-18%) or home cage (-31%) controls. Deprived rats also had reduced GSHtau levels in thalamus compared with home cage controls only. Glutathione levels did not differ among the three groups in any of the other brain areas examined. These results indicate that specific brain areas may be differentially susceptible to oxidative stress after sleep deprivation. The apparent vulnerability of the hypothalamus to these effects may contribute to some of the functional effects of sleep deprivation.
Assuntos
Química Encefálica/fisiologia , Glutationa/metabolismo , Privação do Sono/fisiologia , Animais , Hipotálamo/metabolismo , Hipotálamo/fisiologia , Masculino , Estresse Oxidativo/fisiologia , Ratos , Ratos Wistar , Tálamo/metabolismo , Tálamo/fisiologiaRESUMO
Paradoxical sleep deprivation was performed on rats using platform technique to investigate the oxidative process associated with it. Levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), total glutathione (GSH) and malondialdehyde production were measured in brain of rats under control conditions (C) and those on single large platforms (SLP), multiple large platforms (MLP), single small platforms (SSP) and multiple small platforms (MSP) groups. SOD, CAT and GPx brain activity and malondialdehyde production were not modified by any of the procedures. Brain GSH, however, was significantly reduced in both SSP and SLP groups. These results suggest that paradoxical sleep deprivation per se is not associated with oxidative damage. The observed alterations could be attributed to factors such as immobilization and social isolation present in the single platform techniques.
Assuntos
Estresse Oxidativo/fisiologia , Privação do Sono/fisiologia , Sono REM , Animais , Encéfalo/metabolismo , Catalase/metabolismo , Glutationa/metabolismo , Glutationa Peroxidase/metabolismo , Peroxidação de Lipídeos/fisiologia , Masculino , Malondialdeído/metabolismo , Ratos , Ratos Wistar , Superóxido Dismutase/metabolismoRESUMO
Both partial and total sleep deprivation frequently result in a rebound of paradoxical sleep (PS), as well as of slow-wave or delta sleep. Acute administration of ethanol inhibits PS in normal volunteers. This effect is dose-dependent and consists of increased latency to and reduced duration of paradoxical sleep. It has also been shown that PS rebound may occur on the same night, as blood alcohol concentration (BAC) declines. The present study examined the effects of sleep deprivation prior to ethanol administration on nocturnal-sleep parameters in healthy male volunteers. Polysomnograms were performed with a randomized, crossover design on baseline, placebo, post-placebo, ethanol (0.9 g/kg), and post-ethanol recovery nights. Subjects were submitted to partial (PSD) (n = 6) or total (TSD) (n = 6) sleep deprivation for 40 hours before placebo or ethanol conditions. Results evidenced a PS inhibition after ethanol treatment in both deprivation groups, despite their sleep debt (PSD, placebo = 103.7 minutes and ethanol = 72.7 minutes; TSD, placebo = 111.8 minutes and ethanol = 76.6 minutes). This inhibition was BAC-dependent and specific to PS, since delta sleep remained unaltered. These effects could be due to the reduction of cholinergic release and/or glutamatergic inhibition, both of which modulate acetylcholine release.
Assuntos
Etanol/farmacologia , Privação do Sono , Sono/efeitos dos fármacos , Adulto , Ritmo Delta/efeitos dos fármacos , Etanol/sangue , Humanos , Masculino , Polissonografia , VigíliaRESUMO
Paradoxical sleep (PS) deprivation has been suggested to induce supersensitivity of postsynaptic dopamine (DA) receptors and subsensitivity of acetylcholine (ACh) receptors. Yawning behavior is reduced after PS deprivation and is believed to result from an interaction between ACh and DA systems. Concomitant treatment of PS deprived animals with DA agonists reverses PS deprivation effects on stereotypy and aggressiveness. To examine this possibility on yawning behavior, rats were treated, during the deprivation period, with atropine, methamphetamine, haloperidol or distilled water. Following PS deprivation, rats were injected with apomorphine or pilocarpine and number of yawns was recorded. Atropine increased yawning of PS deprived rats induced by pilocarpine, but not by apomorphine. Treatment with methamphetamine and haloperidol did not change PS deprivation effect on pilocarpine- and apomorphine-induced yawning. The data suggest that reversal of PS deprivation-induced yawning inhibition is mediated distinctly by both acetylcholine and dopamine systems.
Assuntos
Atropina/farmacologia , Agonistas Muscarínicos/farmacologia , Antagonistas Muscarínicos/farmacologia , Pilocarpina/farmacologia , Privação do Sono/fisiologia , Sono REM/fisiologia , Bocejo/efeitos dos fármacos , Animais , Sinergismo Farmacológico , Masculino , Ratos , Ratos Wistar , Receptores Colinérgicos/efeitos dos fármacos , Receptores Colinérgicos/metabolismo , Receptores Colinérgicos/fisiologia , Receptores Dopaminérgicos/efeitos dos fármacos , Receptores Dopaminérgicos/metabolismo , Receptores Dopaminérgicos/fisiologia , Comportamento Estereotipado/efeitos dos fármacosRESUMO
Effects of stress on drug-induced yawning: Constant vs. intermittent stress. PHYSIOL BEHAV 58(1) 181-184, 1995.--Experiment 1 tested whether chronic exposure to immobilization, foot shock or forced swimming would result in suppression of apomorphine-, pilocarpine-, and physostigmine-induced yawning. Immobilization caused suppression of yawning, whereas foot shock and swimming resulted in increased number of yawns. Since interstressor interval was long in the two latter stressors, animals could have recovered and the increase in yawning could be due to the last (acute) exposure to stress. In Experiment 2 we recorded the number of yawns induced by pilocarpine in animals exposed to 1 h of swimming or foot shock. No differences between control and acutely stressed animals were detected. These results suggest that yawning is differently altered by constant and intermittent stressors (i.e., diminished by constant and increased by intermittent stress).
Assuntos
Apomorfina/farmacologia , Nível de Alerta/efeitos dos fármacos , Fisostigmina/farmacologia , Pilocarpina/farmacologia , Estresse Psicológico/complicações , Bocejo/efeitos dos fármacos , Animais , Encéfalo/efeitos dos fármacos , Relação Dose-Resposta a Droga , Masculino , Ratos , Ratos Sprague-Dawley , Receptores Colinérgicos/efeitos dos fármacos , Receptores Dopaminérgicos/efeitos dos fármacosRESUMO
Rats were submitted to paradoxical sleep deprivation (PSD) for 24, 72, or 96 h and were trained on a double aversively motivated task, encompassing a step-through inhibitory avoidance and a classical conditioning of fear to a brief tone serving as conditional stimulus. Retention test of the inhibitory avoidance was performed at the same apparatus of training (without tone presentation). Retention of conditioned fear was assessed in an open field apparatus, where the freezing reaction to the tone was measured. PSD for 24 and 72 h preceding the training session had no effect on either task. However, PSD during the 96 h preceding the training session impaired acquisition of inhibitory avoidance, but had no effect on classically conditioned fear. It is concluded that PSD had differential effects on the two tasks, both aversively motivated and trained at the same time and conditions.