title: Release of immunoreactive somatostatin from hypothalamic cells in culture: inhibition by gamma-aminobutyric acid.
abstract: Primary cultures of dispersed hypothalamic cells were prepared from embryonic rats to study the release of immunoreactive somatostatin. The immunoreactive somatostatin content of these cultures increased during the first 2 weeks after plating and was readily measurable for several weeks thereafter; this material was characterized by gel permeation and reverse-phase chromatography. Depolarization of the cells with 60 mM K+ or with veratridine resulted in a calcium-dependent release of immunoreactive somatostatin which cochromatographed with synthetic somatostatin on reverse-phase chromatography. Tetrodotoxin blocked the veratridine-evoked release. However, even in the absence of exogenous stimuli, immunoreactive somatostatin was released by the cells into the medium. More than 70% of this tonic release was found to be calcium dependent and to be inhibited by tetrodotoxin, indicating that spontaneous electrical activity in the cultures leads to a release of immunoreactive somatostatin. gamma-Aminobutyric acid inhibited the tonic release of immunoreactive somatostatin and this was reversed by bicuculline. These findings support the hypothesis that gamma-aminobutyric acid inhibits somatostatin release in vivo.
mesh_terms: D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002478:Cells, Cultured; D002850:Chromatography, Gel; D007031:Hypothalamus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D011863:Radioimmunoassay; D051381:Rats; D013004:Somatostatin / Q000276:immunology / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology; D014701:Veratridine / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
chemical_list: D013779:Tetrodotoxin; D013004:Somatostatin; D005680:gamma-Aminobutyric Acid; D014701:Veratridine; D011188:Potassium; D002118:Calcium; D001640:Bicuculline