α1-Adrenergic and dopaminergic receptors are involved in the anoretic effect of corticotropin-releasing factor in goldfish

This study investigates the noradrenergic and/or dopaminergic receptors subtypes involved in the anoretic action of CRF in goldfish. Agonists and antagonists of alpha(1)- and alpha(2)-adrenoceptors, and D-1- and D-2-dopaminergic receptors were intracerebroventricularly (ICV) administered alone or in combination with CRF in the case of antagonists. Food intake and hypothalamic content of catecholamines and their metabolites were measured at 2 h postinjection. On one hand, alpha(1)-adrenergic receptor antagonist, but not alpha(2), blocked the anoretic effect of CRF. Moreover, we found a blockade of CRF-induced anoretic action by pretreatment with specific D-1- and D-2-dopaminergic antagonists. On the other hand, the ICV administration of CRF reduced hypothalamic norepinephrine (NE) and dopamine (DA) content, without modifications in their metabolism. Thus, our results suggest that the anoretic effect of CRF appears to be mediated by alpha(1)-adrenergic and dopaminergic receptors in fish. Second, the reduction in hypothalamic NE and DA synthesis could be due to a direct effect of CRF treatment and/or a secondary effect of food intake reduction.