The somatostatin analog, octreotide, causes accumulation of growth hormone-releasing hormone and depletion of angiotensin in the rat hypothalamus

Rats were injected intracerebroventricularly with the somatostatin analog, octreotide (OCT; 0.1 mug) or vehicle, and hypothalamic contents of growth h ormone-releasing hormone (GHRH), angiotensin II, and vasopressin were deter mined 10 min, 1, 3 and 6 h post-injection. OCT elicited an immediate releas e of angiotensin II (10 min) and a rise in GHRH content (1 h) followed by g radual (1-6 h) depletion of accumulated GHRH. Hypothalamic vasopressin was not altered but decreases in pituitary vasopressin occurred 10 min post-inj ection. The OCT-induced alterations in GHRH may explain previously reported changes in sleep whereas angiotensin may mediate OCT-induced drinking, vas opressin secretion and rises in blood pressure via sst2 somatostatin recept ors. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.