Mechanism of action of TRH: involvement of the phosphatidylinositol (PI) response in the action of TRH in rat anterior pituitary cells.
In order to further investigate the molecular basis for the action of TRH, experiments were performed to examine the ability of rat anterior pituitary cells to incorporate [32P]orthophosphate into phospholipids in response to the neurohormone. Addition of 0.1 microM TRH rapidly stimulates the phosphatidylinositol (PI) response. The incorporation of radioactivity into PA and PI is increased as early as in 2 and 5 min after TRH addition, respectively, and reaches 40 and 140% above control, respectively, at 20 min. By contrast, 0.1 microM somatostatin is inactive. TRH exerts its stimulatory effect at an ED50 value of ca. 10 nM. The present results suggest that the PI response is an early event associated with the action of TRH in the anterior pituitary gland.
D000818:Animals; D002478:Cells, Cultured; D005260:Female; D010712:Phosphatidic Acids / Q000096:biosynthesis; D010716:Phosphatidylinositols / Q000096:biosynthesis; D010743:Phospholipids / Q000096:biosynthesis*; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
D010712:Phosphatidic Acids; D010716:Phosphatidylinositols; D010743:Phospholipids; D013973:Thyrotropin-Releasing Hormone