The Inhibitory Effects of Growth Hormone-Releasing Hormone (GHRH)-Antagonist on GHRH, L-Dopa, and Clonidine-Induced GH Secretion in Normal Subjects

Kunihiko Hanew, Aki Tanaka, Atsushi Utsumi, Akira Sugawara, Keishi Abe

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

The relative inhibitory potency of GHRH-Antagonist (GHRH-Ant) to GHRH(1-44)NH2 and mechanism of L-dopa- or clonidine-induced GH release were studied in seven normal subjects using GHRH-Ant. One hundred micrograms of GHRH-Ant (iv for 75 min) did not inhibit plasma GH responses to bolus injection of 100 μg and 10 μg GHRH or simultaneous infusion of 5 μg GHRH (iv for 75 min). However, 200 μg GHRH-Ant (iv for 75 min) significantly inhibited GH release, which was induced by simultaneous infusion of 5 μg GHRH. Although 100 μg GHRH-Ant could not significantly inhibit L-dopa-induced GH release, 200 μg GHRH-Ant almost completely inhibited the response. Similarly, the same dose of GHRH-Ant markedly inhibited the GH-releasing activity of clonidine. It is concluded that the inhibitory potency of GHRH-Ant on GHRH(1-44)NH2 is relatively weak (about 1/60 in molar base), and that L-dopa- or clonidine-induced GH release seems to be mediated by the release of hypothalamic GHRH.

Original languageEnglish
Pages (from-to)1952-1955
Number of pages4
JournalJournal of Clinical Endocrinology and Metabolism
Volume81
Issue number5
DOIs
Publication statusPublished - 1996

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Endocrinology
  • Clinical Biochemistry
  • Biochemistry, medical

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