Somatostatin receptors in the nucleus accumbens modulate dopamine-dependent but not acetylcholine-dependent turning behaviour of rats.

Abstract

The role of somatostatin receptors in the nucleus accumbens shell in rat turning behaviour was studied. Unilateral injection of neither the somatostatin receptor agonist somatostatin (1.0 microg) nor the somatostatin receptor antagonist cyclosomatostatin (100.0 ng) into the nucleus accumbens shell elicited turning behaviour. Unilateral injection of a mixture of dopamine D(1) ((+/-)-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine-7,8-diol, SKF 38393) and D(2/3) (quinpirole) receptor agonists into the nucleus accumbens shell has been found to elicit contraversive pivoting. Somatostatin (0.5 and 1.0 microg) dose-dependently potentiated the contraversive pivoting induced by a mixture of SKF 38393 (1.0 microg) and quinpirole (10.0 microg) injected into the nucleus accumbens shell. This potentiating effect of somatostatin (1.0 microg) on the dopaminergic pivoting was dose-dependently inhibited by cyclosomatostatin (10.0 and 100.0 ng) injected into the nucleus accumbens shell. Unilateral injection of acetylcholine receptor agonist carbachol into the nucleus accumbens shell has been found to elicit contraversive circling. Neither somatostatin (1.0 ?g) nor cyclosomatostatin (100.0 ng) significantly affected the contraversive circling induced by carbachol (5.0 microg) injected into the nucleus accumbens shell. These results suggest that somatostatin receptors in the nucleus accumbens shell play a modulatory role in rat dopaminergic pivoting, but not in rat cholinergic circling.