Attenuation of food intake in chicks by an inverse agonist of cannabinoid receptor 1 administered by either injection or ingestion in hydrocolloid carriers

The cannabinoid receptor (CB1) was studied primarily in mammals where it was found to comprise a link between reward processes and addictive behavior such as food consumption. The purpose of this study was twofold: first to characterize the effect of the chicken CB1 receptor inverse agonist AM251 on food intake, and second, to establish a stress-free approach for application of AM251 to birds using hydrocolloid carriers, which can be mixed with food. A single administration of AM251 by intravenous injection (at 0.85 or 5 mg kg−1 BW) or by ingestion of hydrocolloid carriers entrapping AM251 at a concentration of 5 mg kg−1 BW led to a transient attenuation of food intake. The consequent reduced cumulative food intake and BW were observed in the treated chicks for at least 7 h post-administration, with no gender differences. Circulating levels of AM251, assessed by LC-MS following 48 h of continuous feeding with hydrocolloid carriers containing 50 mg AM251 kg−1 BW day−1, were physiologically significant at 186 ± 73 pmol ml−1. It is concluded that unlike some other factors, which act differently in birds compared to mammals such as ghrelin, CB1 inverse agonists attenuate food intake in chicks similar to its effect in mammals. In addition, the new approach for administration of AM251 to birds in hydrocolloid carriers could provide a simple and stress-free tool for prolonged studies of this control mechanism in birds.

Research highlights► Cannabinoid receptor 1 (CB1) inverse agonists attenuate food intake in broiler chicks. ► A synthetic CB1 inverse agonist, AM251, can be applied to chicks via hydrocolloid carriers. ► Physiologically significant levels of circulating AM251 were observed following AM251 feeding.