Effects of the novel GH secretogogue, hexarelin on GH secretion and phosphatidylinositol hydrolysis by human pituitary somatotrophinomas in cell culture

Abstract

The effects of the novel GH-releasing hexapeptide, Hexarelin, on cultured human pituitary somatotrophinomas were investigated. Hexarelin (0.01 -100 nmol / L) dose-dependently stimulated GH secretion up to 4.6-fold. Maximal effects occurred with 10 nmol / L. These effects were very similar to those observed with GHRP-6. The effects of Hexarelin were reduced by phloretin, an inhibitor of protein kinase C (PKC). The rate of phosphatidylinositol (PI) hydrolysis was markedly increased by Hexarelin in a dose-dependent manner. These results demonstrated that Hexarelin could directly stimulate GH secretion by human pituitary somatotrophs in a PKC-dependent manner, probably via activation of the PI transduction system.

Keywords

Hexarelin / somatotrophinomas / phosphatidylinositol / growth hormone / pituitary

References

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