The Effect of Intracerebroventricular Administration of Somatostatin on Prolactin and TSH Release in Rats

Abstract: We investigated the effect of intracerebroventrciular (icv) administration of somatostatin (SRIF) on prolactin (PRL) and thyroid-stimulating hormone (TSH) release in freely moving rats chronically cannulated with en atrial catheter. The plasma PRL levels were significantly elevated following the icv administration of 0.5 ug SRIF. No further increase in PRL following the icv administration of SRIF were found in the rats in the course of repeated intravenous of injection of 5.0 mg/kg sulpiride, a specific D2 receptor antagonist. On the other hand, the injection of 5.0 /ig SRIF resulted in no significant change in the plasma TSH levels. These results suggest that the effect of SRIF on PRL release was exerted through brain D2 receptors.