The effect of leptin receptor deficiency and fasting on cannabinoid receptor 1 mRNA expression in the rat hypothalamus, brainstem and nodose ganglion

Despite ample evidence for the involvement of the endocannabinoid system in the control of appetite, food intake and energy balance, relatively little is known about the regulation of cannabinoid receptor 1 (CB1R) expression in respect to leptin signalling and fasting. In the present study, we examined CB1R mRNA levels in lean (Fa/?) and obese (fa/fa) male Zucker rats under basal and food-restricted conditions. Using stereological sampling principles coupled with semi-quantitative radioactive in situ hybridization we provide semi-quantitative estimates of CB1R mRNA expression in key appetite regulatory hypothalamic and brainstem areas, as well as in the nodose ganglia. Whereas no effect of fasting were determined on CB1R mRNA levels in the paraventricular (PVN) and ventromedial hypothalamic (VMH) nucleus, in the brainstem dorsal vagal complex or nodose ganglion of lean Zucker rats, CB1R mRNA levels were consistently elevated in obese Zucker rats pointing to a direct influence of disrupted leptin signalling on CB1R mRNA regulation.