Involvement of cocaine- and amphetamine-regulated transcript peptide in the hyperphagic and body weight promoting effects of allopregnanolone in rats

摘要

Allopregnanolone (ALLO), a gamma-aminobutyric acid (GABA) type A receptor active neurosteroid, elicits hyperphagic response in rodents. Since GABA-A receptors are present on the peptidergic neurons in the hypothalamus, we were interested in finding out if ALLO and neuropeptide cocaine- and amphetamine-regulated transcript (CART) interact and influence feeding behavior. While subcutaneous ALLO treatment, for a period of 7 days, produced a significant increase in food intake and body weight, pretreatment with subthreshold dose of CART (intracerebroventricular) attenuated both the effects. On the other hand, subcutaneous administration of dehydroepiandrosterone sulfate (DHEAS; GABA-A inhibitor neurosteroid) for a period of 7 days resulted in a significant reduction in food intake and body weight. These effects of DHEAS were potentiated by intracerebroventricular pretreatment with subeffective dose of CART. The brains of ALLO-treated rats were processed for the immunohistochemical analysis of CART immunoreactive elements. ALLO treatment resulted in a significant reduction in CART immunoreactivity in the hypothalamic arcuate, paraventricular and lateral nuclei, and nucleus accumbens shell. The results of the present study suggest that ALLO and CART might interact in the brain, and influence food intake and body weight. However, further investigations are needed to clarify the precise mechanisms by which ALLO modulate feeding behavior.