Central and peripheral consequences of the chronic blockade of CB1 cannabinoid receptor with rimonabant or taranabant.

J. Neurochem. (2010) 112, 1338–1351. Abstract The endocannabinoid system plays a crucial role in the pathophysiology of obesity. However, the clinical use of cannabinoid antagonists has been recently stopped because of its central side-effects. The aim of this study was to compare the effects of a chronic treatment with the CB1 cannabinoid antagonist rimonabant or the CB1 inverse agonist taranabant in diet-induced obese female rats to clarify the biological consequences of CB1 blockade at central and peripheral levels. As expected, chronic treatment with rimonabant and taranabant reduced body weight and fat content. Interestingly, a decrease in the number of CB1 receptors and its functional activity was observed in all the brain areas investigated after chronic taranabant treatment in both lean and obese rats. In contrast, chronic treatment with rimonabant did not modify the density of CB1 cannabinoid receptor binding, and decreased its functional activity to a lower degree than taranabant. Six weeks after rimonabant and taranabant withdrawal, CB1 receptor density and activity recovered to basal levels. These results reveal differential adaptive changes in CB1 cannabinoid receptors after chronic treatment with rimonabant and taranabant that could be related to the central side-effects reported with the use of these cannabinoid antagonists.