Effect of vasoactive intestinal peptide on monkey prolactin secretion and cyclic AMP in culture: interaction with estradiol and phenol red.
To test the hypothesis that estrogenic compounds may decrease the sensitivity of primate lactotropes to adenylate cyclase-mediated secretagogues, the effect of VIP on prolactin secretion and cAMP levels in serum-free monkey pituitary monolayer cultures was examined in the presence and absence of estradiol (E) and phenol red. In two experimental designs, E treatment was initiated on either the day after dispersion (split plate design) or 10 days after serum-free culture (whole plate design). VIP challenges (5, 50 and 500 nM) were administered for 4 h on days 10 and 20 of culture. There was a significant decrease in the maximal percent stimulation of prolactin by VIP when cultures were treated with E or phenol red. The average percent increase in prolactin at 5, 50 and 500 nM VIP equalled 23, 83 and 156% in the absence of phenol red, but equalled 14, 43 and 112% when E was added to phenol red-free cultures. The percent stimulation by VIP in the presence of phenol red averaged 32, 62 and 97%, but addition of E with phenol red decreased the average stimulation to 26, 45 and 72%, respectively. Basal levels of cAMP were increased by E and phenol red. However, the maximal percent stimulation of cAMP by VIP was decreased in the presence of E and phenol red. In summary, E and phenol red act to decrease the maximal percent stimulation of prolactin secretion by VIP. This effect is reflected by a decrease in the maximal percent stimulation of intracellular cAMP.
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Division of Reproductive Biology and Behavior, Oregon Regional Primate Research Center, Beaverton.
D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D004347:Drug Interactions; D004958:Estradiol / Q000494:pharmacology*; D005109:Extracellular Matrix / Q000502:physiology; D008253:Macaca mulatta; D010635:Phenolphthaleins / Q000494:pharmacology*; D010637:Phenolsulfonphthalein / Q000494:pharmacology*; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism*; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*
D010635:Phenolphthaleins; D014660:Vasoactive Intestinal Peptide; D004958:Estradiol; D011388:Prolactin; D000242:Cyclic AMP; D010637:Phenolsulfonphthalein