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, increased the number of somatostatin (SS) receptors and the affinity constant in frontoparietal cortex membranes. In addition, in the clonidine group, the capacity of SS to inhibit basal and forskolin (FK)-stimulated adenylyl cyclase (AC) activity in the frontoparietal cortex was significantly higher than in the control group. Pretreatment with the alpha 2-adrenoceptor antagonist yohimbine prevented the clonidine-induced changes in SS binding and SS-inhibited AC activity. Yohimbine alone had an opposite effect from clonidine. These experiments provide further evidence that the alpha-adrenergic system modulates the rat frontoparietal cortex somatostatinergic system.