Inhibition of prolactin secretion by endothelin-3 is pertussis toxin-sensitive.
The effect of pertussis toxin (PTX) pretreatment on endothelin-3 (ET-3)-mediated inhibition of prolactin secretion from primary cultures of rat anterior pituitary cells was examined. Monolayer cultures of anterior pituitary cells were treated with either 20 ng/ml PTX dissolved in media or with media alone (control) on the third day of culture. Exactly 24 h after PTX pretreatment, cells were challenged with either 100 nM ET-3 dissolved in media or media alone (control) for 4 or 48 h. ET-3 significantly (P less than 0.01) inhibited prolactin secretion in both the 4 and 48 h incubations. However, if the cells had been previously treated with PTX, ET-3 did not significantly affect prolactin secretion. These data suggest that a PTX-sensitive G protein mediates ET-3-induced inhibition of prolactin secretion and that ET-3 may invoke a signal transduction mechanism in the lactotroph which is distinct from those described in other cell types.
Burris
T P
TP
Department of Biological Science, Florida State University, Tallahassee 32306.
Kanyicska
B
B
Freeman
M E
ME
D000818:Animals; D002478:Cells, Cultured; D016232:Endothelins / Q000494:pharmacology*; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism; D037342:Pertussis Toxin; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism*; D011863:Radioimmunoassay; D051381:Rats; D015398:Signal Transduction; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D016232:Endothelins; D010566:Virulence Factors, Bordetella; D011388:Prolactin; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins