Sa prepro-trh connecting peptide (Prepro-trh 160-169) potentiates trh-induced tsh release from rat perifused pituitaries by stimulating dihydropyridine- and omega-conotoxin-sensitive ca2 channels

Abstract

The stimulation of TSH secretion by TRH involves the phosphatidylinositol second messenger pathway via activation of phospholipase C. This effect is mediated by a GTP-binding protein and leads to a mobilization of intracellular Ca2+ stores and an activation of protein kinase C. However, TRH stimulation also results in an influx of extracellular Ca2+. Since we have previously demonstrated that a non-TRH fragment of the prepro-TRH molecule, the connecting peptide PS4 (prepro-TRH 160-169), was able to potentiate the TRH-induced TSH release in a dose-dependent manner, we attempted to determine whether this potentiation might be due to a Ca2+ -dependent phenomenon and whether a specific class of ..