STIMULATION OF GROWTH HORMONE RELEASE BY LUTEINIZING HORMONE-RELEASING HORMONE AND MELANOCYTE-STIMULATING HORMONE-RELEASE INHIBITING HORMONE IN THE HYPOPHYSECTOMIZED RAT BEARING AN ECTOPIC PITUITARY

Abstract

Intrajugular administration of LHRH [luteinizing hormone-releasing hormone] (0.6 and 1.2 .mu.g) in hypophysectomized rats which received renal grafts of anterior pituitary induced a small but significant rise in plasma GH [growth hormone] 5 and 10 min post-treatment. LHRH, at the same dose levels, was ineffective in weight-matched intact controls. MIF [melanocyte-stimulating hormone-release inhibiting hormone] at the dose of 1.2 .mu.g, induced a slight GH rise 5 min after treatment in hypophysectomized-transplanted rats, while it was ineffective in intact controls. Unlike the 2 hypothalamic peptides, .alpha.-MSH [.alpha.-melanotropin] (0.6 and 1.2 .mu.g) was ineffective as a GH-releaser in transplanted and intact rats.