CHRONIC IMIPRAMINE TREATMENT UP-REGULATES IR(2)-IMIDAZOLINE RECEPTIVESITES IN RAT-BRAIN

A low density of brain IR(2)-imidazoline receptive sites has previousl y been linked to depression. In this study we evaluated brain IR(2)-bi nding sites in a rat model of depression, olfactory bulbectomy, and de termined the effects of chronic imipramine treatment in vivo on these sites. Compared with sham-operated controls, adaptation to olfactory b ulbectomy had no effect on either the density (B-max) or affinity (K-D ) of [H-3]-idazoxan binding to brain IR(2) sites. However, 25 days of imipramine treatment (i.p., 20 mg/kg/day) enhanced significantly the d ensity of IR(2) binding sites, with no change in affinity in both the model and the control group. These results indicate that the brain IR( 2)-imidazoline receptive sites might be a target for antidepressants. Copyright (C) 1996 Elsevier Science Ltd.