Goldfish CB1 mRNA expression is affected by fasting and anandamide administration

The endocannabinoid system has a well-documented pivotal role in the control of mammalian feeding response; nevertheless, some evidence is available regarding a similar role in nonmammalian vertebrates and invertebrates. As in the bonyfish Carassius auratus, CB1 cannabinoid receptors are abundant in brain regions involved in the control of food intake, and fasting affects endocannabinoid levels, in this study the effects of food deprivation and anandamide administration on CB1 expression were evaluated. Fasting led to a time-dependent increase of CB1 mRNA levels in the forebrain, an effect reversed by refeeding. Furthermore, the administration of exogenous anandamide reduced CB1 expression in food-deprived goldfish. Our results support the involvement of CB1 receptors in the control of energy intake in nonmammalian vertebrates.