Cholinergic stimulation of phosphoinositide hydrolysis in rat anterior pituitary.
The production of inositol phosphates in response to carbachol was studied in rat anterior pituitary tissue prelabelled with [3H]inositol. Carbachol (10 microM) stimulated inositol mono-, bis- and trisphosphate production (IP1, IP2 and IP3) by 360 +/- 49, 338 +/- 49 and 503 +/- 49 (mean +/- SEM, P less than 0.001) percent respectively during a 30 min incubation. Mean basal production was 5.4 +/- 0.3, 4.1 +/- 0.5 and 0.9 +/- 0.3 expressed as a percent of total [3H]inositol lipid for IP, IP2 and IP3 respectively. Stimulated inositol phosphate production was dose dependent and detectable after 5 min. Atropine prevented this stimulation indicating mediation via muscarinic receptors. Removal of extracellular Ca2+ reduced both basal and stimulated total inositol phosphate production by 60% and 56% respectively but did not impair carbachol-induced phosphoinositide hydrolysis per se. Pretreatment of pituitary tissue with either somatostatin (5 micrograms/ml) or pertussis toxin (1 microgram/ml) had no effect on either basal or stimulated inositol phosphate production. These results demonstrate a cholinergic stimulation of phosphatidylinositol bisphosphate (PIP2) hydrolysis in the anterior pituitary which may be important in the action of cholinergic agonists on pituitary hormone secretion.
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006868:Hydrolysis; D007295:Inositol Phosphates / Q000378:metabolism; D010277:Parasympathomimetics / Q000494:pharmacology*; D037342:Pertussis Toxin; D010716:Phosphatidylinositols / Q000378:metabolism*; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D051381:Rats; D013004:Somatostatin / Q000494:pharmacology; D013997:Time Factors; D014316:Tritium; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D007295:Inositol Phosphates; D010277:Parasympathomimetics; D010716:Phosphatidylinositols; D010566:Virulence Factors, Bordetella; D014316:Tritium; D013004:Somatostatin; D001285:Atropine; D002217:Carbachol; D037342:Pertussis Toxin; D002118:Calcium