title: Involvement of prostaglandins in the inhibition of growth hormone production in cultured pituitary cells by insulin.
abstract: The effect of insulin was tested on the rate of synthesis and release of growth hormone in cultured rat anterior pituitary cells. Concentrations of insulin between 10(-9) and 10(-7) mol/l (6--600 ng/ml or 0.15--15 mu./ml) inhibited synthesis of growth hormone; 10(-8) mol insulin/l was most effective. The effect was observed after a time-lag of at least 1 h. Insulin at concentrations between 3 x 10(-9) mol/l and 3 x 10(-7) mol/l also inhibited growth hormone secretion in 30 min incubations. The most effective insulin concentration in this case was 3 x 10(-8) mol/l. Insulin (10(-9)-10(-7) mol/l) also decreased the intracellular content of prostaglandins E and F. The effect was rapid, reaching a maximum after 30 min. Indomethacin, an inhibitor of prostaglandin synthetase, dramatically lowered the concentration of prostaglandins in the cells within 30 min; growth hormone synthesis was also decreased, but not until after 2 h of incubation. The results suggest that an initial response to insulin treatment is a lowering of intracellular levels of prostaglandins, which may then mediate a decrease in growth hormone synthesis, after a 1--2 h delay.
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D013006:Growth Hormone / Q000096:biosynthesis* / Q000378:metabolism; D007213:Indomethacin / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology*; D007930:Leucine / Q000378:metabolism; D008297:Male; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D011458:Prostaglandins E / Q000378:metabolism / Q000502:physiology*; D011460:Prostaglandins F / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D012636:Secretory Rate / Q000187:drug effects; D013997:Time Factors
chemical_list: D007328:Insulin; D011458:Prostaglandins E; D011460:Prostaglandins F; D013006:Growth Hormone; D007930:Leucine; D007213:Indomethacin