RESUMO
Sleep and feeding rhythms are highly coordinated across the circadian cycle, but the brain sites responsible for this coordination are unknown. We examined the role of neuropeptide Y (NPY) receptor-expressing neurons in the mediobasal hypothalamus (MBH) in this process by injecting the targeted toxin, NPY-saporin (NPY-SAP), into the arcuate nucleus (Arc). NPY-SAP-lesioned rats were initially hyperphagic, became obese, exhibited sustained disruption of circadian feeding patterns, and had abnormal circadian distribution of sleep-wake patterns. Total amounts of rapid eye movement sleep (REMS) and non-REMS (NREMS) were not altered by NPY-SAP lesions, but a peak amount of REMS was permanently displaced to the dark period, and circadian variation in NREMS was eliminated. The phase reversal of REMS to the dark period by the lesion suggests that REMS timing is independently linked to the function of MBH NPY receptor-expressing neurons and is not dependent on NREMS pattern, which was altered but not phase reversed by the lesion. Sleep-wake patterns were altered in controls by restricting feeding to the light period, but were not altered in NPY-SAP rats by restricting feeding to either the light or dark period, indicating that disturbed sleep-wake patterns in lesioned rats were not secondary to changes in food intake. Sleep abnormalities persisted even after hyperphagia abated during the static phase of the lesion. Results suggest that the MBH is required for the essential task of integrating sleep-wake and feeding rhythms, a function that allows animals to accommodate changeable patterns of food availability. NPY receptor-expressing neurons are key components of this integrative function.
Assuntos
Núcleo Arqueado do Hipotálamo/metabolismo , Ritmo Circadiano , Ingestão de Alimentos , Comportamento Alimentar , Neurônios/metabolismo , Receptores de Neuropeptídeo Y/metabolismo , Sono , Vigília , Animais , Núcleo Arqueado do Hipotálamo/efeitos dos fármacos , Núcleo Arqueado do Hipotálamo/patologia , Núcleo Arqueado do Hipotálamo/fisiopatologia , Restrição Calórica , Ritmo Circadiano/efeitos dos fármacos , Corticosterona/metabolismo , Ingestão de Alimentos/efeitos dos fármacos , Comportamento Alimentar/efeitos dos fármacos , Hiperfagia/metabolismo , Hiperfagia/fisiopatologia , Hibridização In Situ , Masculino , Neurônios/efeitos dos fármacos , Neurônios/patologia , Neuropeptídeo Y/metabolismo , Obesidade/metabolismo , Obesidade/fisiopatologia , Fotoperíodo , Ratos , Ratos Sprague-Dawley , Receptores de Neuropeptídeo Y/genética , Saponinas/toxicidade , Sono/efeitos dos fármacos , Transtornos do Sono-Vigília/metabolismo , Transtornos do Sono-Vigília/fisiopatologia , Sono REM , Fatores de Tempo , Vigília/efeitos dos fármacosRESUMO
Two-thirds of all adults age 65 or older are either irregularly active or completely sedentary. With this inactivity comes an increased risk of chronic diseases, including coronary heart disease, hypertension, diabetes, osteoporosis, and depression. Adequate aerobic exercise--even when started as late as age 60--is associated with a 1- to 2-year increase in life expectancy, as well as increased functional independence. Even chairbound patients can benefit from a program of simple exercises. To help prevent injuries, your exercise prescription should include stretching exercises and exercises to strengthen the muscles surrounding weak joints.