SOMATOSTATIN RECEPTORS COUPLED TO THE INHIBITION OF ADENYLYL-CYCLASE IN THE RAT FRONTOPARIETAL CORTEX ARE MODULATED BY ALPHA(2) ADRENOCEPTORS

The administration of an alpha(2)-adrenoceptor agonist, clonidine, inc reased the number of somatostatin (SS) receptors and the affinity cons tant in frontoparietal cortex membranes. In addition, in the clonidine group, the capacity of SS to inhibit basal and forskolin (FK)-stimula ted adenylyl cyclase (AC) activity in the frontoparietal cortex was si gnificantly higher than in the control group. Pretreatment with the al pha(2)-adrenoceptor antagonist yohimbine prevented the clonidine-induc ed changes in SS binding and SS-inhibited AC activity. Yohimbine alone had an opposite effect from clonidine. These experiments provide furt her evidence that the alpha(2)-adrenergic system modulates the rat fro ntoparietal cortex somatostatinergic system.