Somatostatin secretion and action in the regulation of growth hormone secretion.
The inhibition of growth hormone (GH) secretion by the hypothalamic peptide, somatostatin, is mediated by two critical factors: the concentration of the peptide in hypothalamic portal plasma and the number of somatostatin ( SRIF) receptors on the somatotroph. The secretory patterns of SRIF and GH- releasing hormone (GRH) in portal blood of unanesthetized sheep is pulsatile and a close relationship of GRH pulses to those of GH secretion was documented, while those of SRIF appear to have more of a modulatory role on the responses to GRH. Peripheral infusion of SRIF at a rate to provide concentrations comparable to those in the portal system leads to a desensitization of SRIF effects on the somatotroph, likely mediated by down-regulation of SRIF receptors. These effects are believed to modulate the GH responses to GRH secretion in the generation of pulsatile GH secretion.[1]References
- Somatostatin secretion and action in the regulation of growth hormone secretion. Frohman, L.A., Downs, T.R., Kelijman, M., Clarke, I.J., Thomas, G. Metab. Clin. Exp. (1990) [Pubmed]
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