Abstract
Central regulation of the feeding behavior in rats is considered to be very complicated since it involves many neurotransmitters and their interactions. The details of these are not fully understood at present. In this study, the influence of plasma corticosterone (CORT) levels on food consumption stimulated by a_2-adrenergic agonist (clonidine), opioid peptides ([D-Ala^2, D-Leu^5] enkephalinamide : DADL, [D-Ala^2, N-Me-Phe^4, Gly^5-ol] enkephalin : DAGO and dynorphin 1-13 : DYN) and benzodiazepine (BZ) -GABA agonists (diazepam: DZ and muscimol) were examined in rats. Although adrenalectomy inhibited α_2-adrenergic agonist (clonidine), δ-agonist (DADL) and κ-agonist (DYN) -induced increase in food consumption, subcutaneous injection of CORT was restored food consumption in a dose-dependent manner. On the other hand, increase in food consumption by μ-agonist (DAGO) and BZ-GABA agonists not be influenced by the concentration of circulating CORT. The results of this study are suggested that circulating CORT may act on the hypothalamus directly and/or indirectly to modulate feeding behavior, and this is one of the factors that modulate α_2-adrenergic agonist and δ-, κ-opioid peptides-induced increase in the food consumption of rats.
