Adrenalectomy impairs vasoactive intestinal peptide-induced changes in food intake and plasma parameters
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The aim of this study is to evaluate the effects of adrenalectomy (ADX) and glucocorticoid in the changes induced by intracerebroventricular (ICV) administration of vasoactive intestinal peptide (VIP) on food intake and plasma parameters, as well as VIP receptor subtype 2 (VPAC2) mRNA expression in different hypothalamic nuclei of male rats.
Male Wistar rats (260–280 g) were subjected to ADX or sham surgery, 7 days before the experiments. Half of ADX animals received corticosterone (ADX + CORT) in the drinking water. Animals with 16 h of fasting received ICV microinjection of VIP or saline (0.9% NaCl). After 15 min: (1) animals were fed, and the amount of food ingested was quantified for 120 min; or (2) animals were euthanized and blood was collected for biochemical measurements. Determination of VPAC2 mRNA levels in LHA, ARC, and PVN was performed from animals with microinjection of saline.
VIP treatment promoted the anorexigenic effect, which was not observed in ADX animals. Microinjection of VIP also induced an increase in blood plasma glucose and corticosterone levels, and a reduction in free fatty acid plasma levels, but adrenalectomy abolished these effects. In addition, adrenalectomy reduced mRNA expression of VPAC2 in the lateral hypothalamic area and arcuate nucleus, but not in the paraventricular nucleus.
These results suggest that adrenal glands are required for VIP-induced changes in food intake and plasma parameters, and these responses are associated with reduction in the expression of VPAC2 in the hypothalamus after adrenalectomy.
KeywordsVIP Glycemia Corticosterone Free fatty acids Arcuate nucleus of the hypothalamus VPAC2 receptor expression
We would like to thank the financial support of Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Estado do Paraná, Brasil, for the grants (protocol numbers 23275, 8277, and 24732). MCGS thanks Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for PhD fellowship.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving animals were in accordance with the local Ethics Commission on the Use of Animals of UEL (protocol number 14371201744).
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