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Comparison of the Effects of ATP, Mg 2+ , and MgATP on the Release of Luteinizing Hormone‐Releasing Hormone from Isolated Hypothalamic Granules
Author(s) -
Burrows G. Howard,
Barnea Ayalla
Publication year - 1982
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1982.tb08664.x
Subject(s) - incubation , chemistry , luteinizing hormone , incubation period , in vitro , hormone , endocrinology , medicine , biophysics , biochemistry , biology
The effect of ATP, Mg 2+ , or MgATP on the release of luteinizing hormone‐releasing hormone (LH‐RH) from hypothalamic granules was examined under in vitro conditions. Granules, isolated from adult male hypothalami, were incubated at 37°C in a buffered (pH 7.8) medium containing 0.15 m ‐KCl. The addition of ATP to the incubation mixture did not stimulate the release of LH‐RH. In contrast, the addition of MgATP stimulated the release of LH‐RH, the release being 62% greater than control. The addition of Mg 2+ to the incubated granules also stimulated the release of LH‐RH. However, the magnitude of this Mg 2+ ‐stimulated release of LH–RH was significantly ( P < 0.01) lower than that of the MgATP‐stimulated release, indicating that ATP stimulates LH‐RH release in a Mg 2+ ‐dependent manner. As both MgATP and Mg 2+ alone stimulated LH‐RH release, we characterized further these two release processes by incubating the granules under one of the following conditions: incubation at 4°C in a buffered medium containing 0.15 m ‐KCl or incubation at 37°C in a medium that does not contain KCl. Under these two incubation conditions, the MgATP‐stimulated release of LH‐RH was not manifested, whereas the Mg 2+ ‐stimulated release of LH‐RH was manifested. On the basis of these differences, we propose that two different processes can lead to the release of LH‐RH from isolated hypothalamic granules: one process involves ATP and Mg 2+ (MgATP) and another process involves Mg 2+ alone.