What is the role of growth hormone (GH) in the pathophysiology of hyposomatotropism (growth hormone deficiency [GHD])?

Updated: Jan 24, 2019
  • Author: Sunil Kumar Sinha, MD; Chief Editor: Robert P Hoffman, MD  more...
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Answer

The hypothalamus communicates with the anterior pituitary gland by releasing of hypothalamic peptides, which are subsequently transported in the hypophyseal portal circulation (ie, the blood supply and communication between the hypothalamus and the adenohypophysis). GH is secreted in a pulsatile pattern as a single-chain, 191-amino acid, 22-kDa protein.

Two specific hypothalamic peptides play major regulatory roles in GH secretion: growth hormone-releasing hormone (GHRH) and somatotropin-releasing factor. Amplitudes and frequencies for release of GHRH and somatotropin-releasing factor, as well as GH, differ between boys and girls and may partially account for differences in the phenotypes between the sexes.

Several neurotransmitters and neuropeptides also control GH secretion by directly acting on somatotrophs or by indirectly acting by means of hypothalamic pathways. These neurotransmitters include pituitary adenylate cyclase activating polypeptide (PACAP), galanin, pituitary-specific transcription factor-1 (Pit-1), prophet of Pit-1 (PROP1), HESX1, serotonin, histamine, norepinephrine, dopamine, acetylcholine, gamma-aminobutyric acid, thyrotropin-releasing hormone, vasoactive intestinal peptide, gastrin, neurotensin, substance P, calcitonin, neuropeptide Y, vasopressin, and corticotropin-releasing hormone. [18, 19, 20]


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