Abstract
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.
Original language | English (US) |
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Pages (from-to) | 576-585 |
Number of pages | 10 |
Journal | Neuroendocrinology |
Volume | 51 |
Issue number | 5 |
DOIs | |
State | Published - 1990 |
Keywords
- Cyclic AMP
- Estradiol
- Monkey
- Phenol red
- Pituitary, Prolactin
- Vasoactive intestinal peptide
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Endocrinology
- Endocrine and Autonomic Systems
- Cellular and Molecular Neuroscience