Neuroendocrine regulation of growth hormone secretion in sheep II. Effect of somatostatin on growth hormone and glucose levels

Abstract The effect of intravenous ( iv ) and intracerebroventricular ( icv ) administration of somatostatin on the plasma levels of growth hormone (GH) and glucose was studied in sheep. Intravenous somatostatin decreased (P iv had no effect on plasma glucose levels. When given icv neither 1.8 μg, 18 μg nor 180 μg somatostatin had any significant effect of plasma GH levels, although there was a significant (P icv . Plasma glucose levels did not increase following injection of somatostatin icv at 1.8 or 18 μg, but there was a clear hyperglycaemic episode following 180 μg icv . Despite a lack of effect of somatostatin on GH release when given icv , there was a clear elevation (P icv administration of a somatostatin antiserum. These data indicate that iv administration of somatostatin at pharmacological levels can depress unstimulated GH levels in sheep while administration icv does not. Central administration of somatostatin increases plasma glucose levels only at high doses and seems unlikely to be of physiological importance in glucose homeostasis.