Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2007636 | Peptides | 2009 | 7 Pages |
Abstract
The neuropeptide EI (NEI) is derived from proMCH. It activates GnRH neurons, and has been shown to stimulate the LH release following intracerebroventricular administration in several experimental models. The aim of the present paper was to evaluate NEI actions on pituitary hormone secretion and cell morphology in vitro. Pituitary cells from female rats were treated with NEI for a wide range of concentrations (1-400Â ÃÂ 10â8Â M) and time periods (1-5Â h). The media were collected and LH, FSH, PRL, and GH measured by RIA. The interaction between NEI (1, 10 and 100Â ÃÂ 10â8Â M) and GnRH (0.1 and 1Â ÃÂ 10â9Â M) was also tested. Pituitary cells were harvested for electron microscopy, and the immunogold immunocytochemistry of LH was assayed after 2 and 4Â h of NEI incubation. NEI (100Â ÃÂ 10â8Â M) induced a significant LH secretion after 2Â h of stimulus, reaching a maximum response 4Â h later. A rapid and remarkable LH release was induced by NEI (400Â ÃÂ 10â8Â M) 1Â h after stimulus, attaining its highest level at 2Â h. However, PRL, GH and FSH were not affected. NEI provoked ultrastructural changes in the gonadotrophs, which showed accumulations of LH-immunoreactive granules near the plasma membrane and exocytotic images, while the other populations exhibited no changes. Although NEI (10Â ÃÂ 10â8Â M), caused no action when used alone, its co-incubation with GnRH (1Â ÃÂ 10â9Â M), promoted a slight but significant increase in LH. These results demonstrate that NEI acts at the pituitary level through a direct action on gonadotrophs, as well as through interaction with GnRH.
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Authors
Ana LucÃa De Paul, Andrés Maximiliano Attademo, Ruben Walter Carón, Marta Soaje, Alicia Inés Torres, Graciela Alma Jahn, MarÃa Ester Celis,