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Neurotensin stimulates CRH and ACTH release by rat adrenal medulla in vitro
G Mazzocchi1, L K Malendowicz, P Rebuffat
1Department of Anatomy, University of Padua, Padova, Italy.
Abstract:
Neurotensin (NT) is a 13-amino acid peptide, widely distributed in the central and peripheral nervous system, which is able to stimulate the activity of the hypothalamo-pituitary CRH-ACTH system. We investigated by RIA the effect of NT on the release of CRH and ACTH immunoreactivities (ir) by rat adrenal medulla in vitro. NT enhanced the release of both CRH-ir and ACTH-ir, the maximal effective concentration being 10(-8) M. [D-Trp11]-NT, a specific NT receptor antagonist, abrogated the effects of NT. The stimulatory effect of 10(-8) M NT on ACTH-ir release was blocked by alpha-helical-CRH (an antagonist of CRH receptors), thereby suggesting that the enhancement in ACTH secretion is consequent to the stimulation of CRH release. These findings suggest that NT is a stimulator not only of the central (hypothalamo-pituitary), but also of the peripheral (intramedullary), branch of the CRH-ACTH system.