Galanin Secretion from Anterior Pituitary Cellsin VitroIs Regulated by Dopamine, Somatostatin, and Thyrotropin-Releasing Hormone*
| Autor: | James F. Hyde, Brian K. Keller |
|---|---|
| Rok vydání: | 1991 |
| Předmět: |
Male
endocrine system medicine.medical_specialty Pituitary gland Somatotropic cell Dopamine Thyrotropin-releasing hormone Galanin Prolactin cell Endocrinology Anterior pituitary Pituitary Gland Anterior Thyrotropic cell Internal medicine medicine Animals Thyrotropin-Releasing Hormone Cells Cultured Estradiol Chemistry Neuropeptides digestive oral and skin physiology Hormones Rats Inbred F344 Prolactin Rats medicine.anatomical_structure Somatostatin nervous system Growth Hormone Female Peptides hormones hormone substitutes and hormone antagonists |
| Zdroj: | Endocrinology. 128:917-922 |
| ISSN: | 1945-7170 0013-7227 |
| DOI: | 10.1210/endo-128-2-917 |
| Popis: | Lactotrophs, somatotrophs, and thyrotrophs have been shown to contain immunoreactive galanin. Furthermore, estrogen stimulates galanin mRNA and peptide levels in the rat anterior pituitary, particularly within lactotrophs. To determine whether galanin is released from the anterior pituitary in a regulated manner, we used cultured pituitary cells from male and ovariectomized Fischer 344 rats implanted with estrogen-containing capsules. Anterior pituitary cells (5 x 10(5) cells/well) were challenged (0.5-3 h) with hypothalamic factors known to regulate anterior pituitary hormone secretion, and medium galanin levels were measured by RIA. In female pituitary cells, galanin secretion was inhibited by dopamine (10 and 100 nM) and stimulated by TRH (20 and 100 nM). Although galanin release was significantly lower in male pituitary cells, dopamine and TRH inhibited and stimulated galanin secretion, respectively. Medium galanin levels were also significantly reduced by somatostatin (5 nM) in both female and male cells. The pattern of PRL release in response to dopamine, TRH, and somatostatin was similar to that observed for galanin, regardless of the sex of the pituitary donor. Although galanin has been localized in somatotrophs, 5 nM GH-releasing hormone (GRF) failed to alter galanin release in male as well as female pituitary cells; GH secretion was significantly increased by GRF. LHRH (5 nM) and CRF (5 nM) failed to alter galanin release in vitro. We conclude that in estrogen-exposed pituitary cells obtained from male and ovariectomized Fischer 344 rats: 1) galanin secretion is inhibited by dopamine and somatostatin, and stimulated by TRH; 2) GRF, LHRH, and CRF do not regulate galanin release in these cells; and 3) the profile of the regulated pathway for galanin release suggests that the primary location of galanin is the lactotroph, probably within secretory granules. |
| Databáze: | OpenAIRE |
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