Somatostatin is targeted to the regulated secretory pathway of gonadotrophs in transgenic mice expressing a metallothionein-somatostatin gene.
The pituitaries of transgenic mice that express a metallothionein-somatostatin fusion gene contain high concentrations of somatostatin-14 exclusively in the gonadotrophic cells. The purpose of this study was to determine whether somatostatin expressed from the foreign fusion gene enters the normal secretory pathway within these cells. Immuno-gold labeling of serial thin sections localized somatostatin to the secretory granules of gonadotropin-producing cells. The gonadotroph-specific hypophysiotropic factor, luteinizing hormone-releasing hormone caused a dose-dependent secretion of somatostatin when applied to primary pituitary cultures from these mice. Growth hormone-releasing hormone, thyrotropin-releasing hormone, corticotropin releasing factor, and dopamine did not affect somatostatin secretion. These experiments demonstrate that a neurosecretory peptide encoded by a foreign gene can enter the regulated secretory pathway of pituitary cells from transgenic mice.
D000818:Animals; D002478:Cells, Cultured; D003594:Cytoplasmic Granules / Q000032:analysis; D005260:Female; D005818:Genetic Engineering; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D008297:Male; D008668:Metallothionein / Q000235:genetics*; D051379:Mice; D013004:Somatostatin / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D015032:Zinc / Q000494:pharmacology
D007987:Gonadotropin-Releasing Hormone; D013004:Somatostatin; D008668:Metallothionein; D015032:Zinc