Efeito da adrenalectomia sobre a liberacao hipotalamica de serotonina, induzida por alimento, em ratos normais e obesos

Efeito da adrenalectomia sobre a liberacao hipotalamica de serotonina, induzida por alimento, em ratos normais e obesos

Título alternativo Effect of adrenalectomy on food-induced hypothalamic serotonin release serotonin in normal and obese rats
Autor Guimaraes, Regina Barros Autor UNIFESP Google Scholar
Resumo The hypothalamic serotonergic system is involved in the regulation of energy homeostasis, due to its ability to reduce food intake and stimulate energy expenditure. Disturbances of these mechanisms can cause obesity. Insulin and corticosterone have been shown to sfimulate the serotonergic transmission. ln the present study, we used brain microdialysis to evaluate the effect of adrenalectomy on the feeding-evoked release of 5-HT in the lateral hypothalamic area (LHA) of normal (N) and monosodium glutamate (MSG)-obese rats, a hypophagic/hypometabolic obesity model. Circulating levels of corticosterone, insulin, and glucose and hepatic glycogen content were also measured. Three days following sham adrenalectomy (FADX) or adrenalectomy (ADX), the ovemight-fasted animais were perfused with artificial CSF and 20 min. microdialysate salnple were collected before (basal) and up to 2 hours (samples C l to C6) after the presentation of a palatable food mash (powdered chow:water 1:2). 5-HT and 5-HIAA were determinei by HPLC. Daily chow intake was reduced by adrenalectomy whilst individual 20 min. intakes were similar between FADX and ADX animais. 5-HT release was significantly increased by food intake in FADX rats, the maximum increment over basal release being of l 19 n 59 por cento in N and l l l n 3 7 por cento in MSG rats. Fasfing insulin and corticosterone levels were elevated in MSG FADX rats. After food intake, corticosterone levels fell in MSG FADX and increased in N FADX rats, and becatne similar between the groups. Adrenalectomy completely abolished the serotonin release induced by food intake. The data indicate that the LHA serotonergic transmission participares in the physiological response to feeding, probably exerting a modulatory influence on energv intake. MSG-obese rats showed a nonnal 5-HT activafion. The presence of similar corticosterone levels probably contributed to this response, due to the stimulatory effect of physlological levels of glucocorticoids on 5-HT transmission. The abolition of the serotonergic response in ADX rats may rely on the adrenalectomy-induced activafion of both 5-HTlA receptors and CRH production, the latter being an anorexigenic factor that may mediate serotonin effects. This study emphasizes the importance of the functional interrelationships of the serotonergic system and the hormones of the HHA axis in the conuol of energy homeostasis
Palavra-chave Serotonina
Ingestão de Alimentos
Obesidade
Adrenalectomia
Microdiálise
Hipotálamo
Idioma Português
Data de publicação 2000
Publicado em São Paulo: [s.n.], 2000. 67 p. ilus.
Publicador Universidade Federal de São Paulo (UNIFESP)
Extensão 67 p.
Direito de acesso Acesso restrito
Tipo Dissertação de mestrado
Endereço permanente http://repositorio.unifesp.br/handle/11600/16849

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