Two distinct events underlie the MgATP-stimulated release of luteinizing hormone releasing hormone from isolated hypothalamic granules

Abstract

We have previously demonstrated that MgATP stimulates the release of luteinizing hormone releasing hormone (LHRH) from isolated hypothalamic granules and that this stimulation has a requirement for monovalent ions. To assess the role of the monovalent ions in the release process, granules (isolated from hypothalami of adult male rats) were incubated in buffered medium containing MgATP in the presence or absence of KC1. When granules were incubated in the absence of KC1, MgATP did not lead to LHRH release. However, when KC1 was added to the MgATP-treated granules, a rapid (1 min) release of LHRH occurred. Based on these results we propose that the process of MgATP-stimulated release of LHRH from isolated hypothalamic granules is comprised of two distinct events: a priming event and a release event. During the priming event, MgATP interacts with the LHRH granule which leads to a change in the granule such that the release event, initiated by monovalent ions, can occur.