Article date: 1992/1/1
PubMed ID: 1335954
Journal name: Hormone research (ISSN: 0301-0163)
The effect of muscimol, a specific potent GABAA receptor agonist, on prolactin release from human prolactin-secreting tissue was investigated using a perifusion system. Perifusion studies on normal rat anterior pituitary tissue, which has identical GABA receptors to those found in normal human pituitary glands, show that muscimol has a specific biphasic effect on prolactin release. This is characterized by an initial transient stimulation (222.3 +/- 21.6% of basal) lasting for 5-10 min followed by a more prolonged inhibitory phase (63.9 +/- 3.1% inhibition of basal). Five human prolactin-secreting adenomas were studied, and in none of the tumours could a biphasic response be demonstrated. One of the prolactin-secreting adenomas had a blunted inhibitory response, but the other 4 showed no inhibitory effect of muscimol on prolactin release. Muscimol had no significant effect on basal or thyrotropin-releasing-hormone (TRH)-stimulated prolactin secretion from GH3 rat pituitary tumour cells. These studies suggest that the GABAergic effect on prolactin secretion is absent or altered in both rat and human prolactin-secreting tumour cells.
Author List: Jones T H, Brown B L, Cullen D R, Dobson P R
Publication Types: Journal Article
Substances mentioned in the article: Receptors, GABA-A; Muscimol; bicuculline methiodide; Thyrotropin-Releasing Hormone; Prolactin; Bicuculline;
Mesh terms: Adult; Animals; Bicuculline/analogs & derivatives; Dose-Response Relationship, Drug; Female; Humans; Male; Middle Aged; Muscimol/pharmacology; Neoplasms, Hormone-Dependent/drug therapy; Pituitary Gland/drug effects; Pituitary Neoplasms/drug therapy; Prolactin/secretion; Prolactinoma/drug therapy; Rats; Receptors, GABA-A/physiology; Thyrotropin-Releasing Hormone;