RESUMO
STUDY OBJECTIVES: Interspecific variation in sleep measured in captivity correlates with various physiological and environmental factors, including estimates of predation risk in the wild. However, it remains unclear whether prior comparative studies have been confounded by the captive recording environment. Herein we examine the effect of predation pressure on sleep in sloths living in the wild. DESIGN: Comparison of two closely related sloth species, one exposed to predation and one free from predation. SETTING: Panamanian mainland rainforest (predators present) and island mangrove (predators absent). PARTICIPANTS: Mainland (Bradypus variegatus, five males and four females) and island (Bradypus pygmaeus, six males) sloths. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Electroencephalographic (EEG) and electromyographic (EMG) activity was recorded using a miniature data logger. Although both species spent between 9 and 10 h per day sleeping, the mainland sloths showed a preference for sleeping at night, whereas island sloths showed no preference for sleeping during the day or night. Standardized EEG activity during nonrapid eye movement (NREM) sleep showed lower low-frequency power, and increased spindle and higher frequency power in island sloths when compared to mainland sloths. CONCLUSIONS: In sloths sleeping in the wild, predation pressure influenced the timing of sleep, but not the amount of time spent asleep. The preference for sleeping at night in mainland sloths may be a strategy to avoid detection by nocturnal cats. The pronounced differences in the NREM sleep EEG spectrum remain unexplained, but might be related to genetic or environmental factors.
Assuntos
Animais Selvagens/fisiologia , Comportamento Predatório , Sono/fisiologia , Bichos-Preguiça/fisiologia , Animais , Animais Selvagens/psicologia , Nível de Alerta/fisiologia , Benzodiazepinas/metabolismo , Dieta/veterinária , Eletroencefalografia , Eletromiografia , Felidae/fisiologia , Feminino , Ilhas , Masculino , Panamá , Floresta Úmida , Sono REM/fisiologia , Bichos-Preguiça/psicologia , Fatores de Tempo , Vigília/fisiologiaRESUMO
Oleamide is a lipid with diverse properties, including cannabinoid-like activity. For example, it induces the classic triad of effects attributable to these molecules: decrease in core temperature, hypolocomotion, and reduction in pain perception. However, as it binds to the cannabinoid receptors (CB1) only at high concentrations, it is not considered an actual endocannabinoid. In this study, we tested the effect of oleamide on food intake and sexual behavior and compared it to the effect induced by anandamide. Results indicate that oleamide and anandamide increased food intake during the 3h post-injection. In addition, anandamide but not oleamide induced changes in sexual performance. This study further supports the role of endocannabinoids in food ingestion and male sexual behavior and gives additional support to the notion that, although oleamide might not be an endocannabinoid, it shares some effects with them.
Assuntos
Ácidos Araquidônicos/farmacologia , Moduladores de Receptores de Canabinoides/farmacologia , Ingestão de Alimentos/efeitos dos fármacos , Ácidos Oleicos/farmacologia , Comportamento Sexual/efeitos dos fármacos , Animais , Relação Dose-Resposta a Droga , Endocanabinoides , Hipnóticos e Sedativos/farmacologia , Masculino , Alcamidas Poli-Insaturadas , Ratos , Ratos WistarRESUMO
Clinical studies suggest that depression facilitates alcohol abuse. Depressed individuals also have increased rates of smoking, and it has been suggested that nicotine may improve depression. It is therefore possible that nicotine may reduce alcohol use in depression. To investigate this potential relationship, we evaluated alcohol intake in an animal model of depression, which consists of administering clomipramine (CLI), a preferential serotonin reuptake inhibitor, to neonatal rats. This pharmacological manipulation produces adult depression-like behaviors, such as reduced aggressiveness, decreased pleasure seeking, diminished sexual activity, increased locomotor activity and increased REM sleep. In this study, we found that CLI rats exhibited significantly higher locomotor activity, lower aggressiveness and higher alcohol intake than control rats. Chronic administration of a low dose of nicotine (0.25 mg/kg/day) or a sham operation did not modify these behaviors. However, chronic administration of nicotine at a higher dose (1.5 mg/kg/day) significantly increased aggressive behavior and reduced alcohol intake in CLI rats. The effect of nicotine on alcohol intake lasted at least 1 month after cessation of nicotine administration. These results indicate that nicotine reverted some depression signs and reduced alcohol self-administration in the CLI model of depression.
Assuntos
Consumo de Bebidas Alcoólicas/tratamento farmacológico , Depressão/tratamento farmacológico , Modelos Animais de Doenças , Nicotina/uso terapêutico , Consumo de Bebidas Alcoólicas/psicologia , Animais , Depressão/psicologia , Masculino , Atividade Motora/efeitos dos fármacos , Atividade Motora/fisiologia , Nicotina/farmacologia , Ratos , Ratos Long-EvansRESUMO
La mariguana es uno de los productos ilícitos de abuso que más se usa en el mundo. Los mecanismos por los cuales afecta al cerebro se han estudiado exhaustivamente en los últimos 40 años, pero se han entendido mejor en la última década. Por ejemplo, conocer los receptores a los que se une la mariguana ha sido un gran descubrimiento en el área de las neurociencias. Asimismo, la descripción de ligandos endógenos, los endocanabinoides, ha arrojado luz para entender la fisiología cerebral que regula desde el dolor hasta el placer y desde el sexo hasta el pensamiento.Por todos estos efectos, los endocanabinoides son un tema de estudio con fines terapéuticos.