Interplay of the endocannabinoid system with neuropeptide Y and corticotropin-releasing factor in the goldfish forebrain.

Based on pharmacological, behavioral, and neuroanatomical studies, the endocannabinoid system appears to be pivotal in some neuroendocrine mechanisms, such as modulation of vertebrate reproduction, stress, and food intake. The present study aimed to investigate the involvement of the endocannabinoid system in the control of the feeding response in the goldfish. By means of immunohistochemistry techniques, using anti-CB1 cannabinoid receptor, anti-corticotropin-releasing factor (CRF), and anti-neuropeptide Y (NPY) antisera on brain sections of Carassius auratus, we found a topographical co-distribution of the three signaling molecules through the preoptic area and posterior lobes of the hypothalamus and even a co-localization of CB1 and NPY in the telencephalon. Previous results have shown that food deprivation in goldfish is accompanied by a significant increase of anandamide (AEA) levels in the telencephalon and AEA causes a dose-dependent effect on food intake. We have thus investigated the possible influence of intraperitoneal AEA injections on NPY expression. Our results indicate an interplay between the endocannabinoid system and orexigenic and anorexigenic molecules, such as NPY and, possibly, CRF.