Inhibitory effect of analogues of cyclic nucleotides and cholera toxin on relaxin release from cultured porcine luteal cells.
The role of cyclic nucleotides (cyclic 3',5'-adenosine monophosphate [cAMP] and cyclic 3',5'-guanosine monophosphate [cGMP]) in the regulation of relaxin release from large porcine luteal cells was examined by use of a reverse hemolytic plaque assay. In this assay, luteal cells are cocultured in monolayers with protein-A-coupled ovine erythrocytes. In the presence of porcine relaxin antiserum and complement, a zone of hemolysis--a plaque--develops around relaxin-releasing luteal cells. The rate of development of plaques in time-course studies has been used as an index of the rate of relaxin release, and the size of plaques formed has been employed as a record of the cumulative amount of relaxin released by each cell. Treatment of monolayers with dibutyryl cAMP (dbcAMP, 60 mM) and dibutyryl GMP (dbcGMP, 15 mM resulted in a prompt inhibition in the rate of plaque formation. In addition, dbcAMP treatment reduced the average size of plaques formed. The stimulatory effect of prostaglandin F2 alpha (PGF2 alpha 10(-6) M) on relaxin release was significantly attenuated by combined treatment with dbcAMP (60 mM). Cholera toxin treatment (500 ng/ml) effectively reduced the average size of plaques formed, but neither this agent nor the beta-adrenergic agonist, isoproterenol (up to 5 X 10(-3) M), influenced the rate of plaque formation. These results--which provide evidence to show that both basal and stimulated relaxin release by large porcine luteal cells can be inhibited by the cyclic nucleotide analogues, dbcAMP and dbcGMP--are consistent with the view that these compounds have the potential to act as a negative regulatory mechanism for relaxin release.(ABSTRACT TRUNCATED AT 250 WORDS)
Taylor
M J
MJ
Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine, Iowa State University, Ames 50011.
Clark
C L
CL
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology*; D002478:Cells, Cultured; D002772:Cholera Toxin / Q000494:pharmacology*; D003338:Corpus Luteum / Q000378:metabolism*; D006152:Cyclic GMP / Q000031:analogs & derivatives*; D003995:Dibutyryl Cyclic GMP / Q000494:pharmacology*; D015237:Dinoprost; D005260:Female; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D008184:Luteal Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011460:Prostaglandins F / Q000494:pharmacology; D012065:Relaxin / Q000378:metabolism*; D013552:Swine / Q000502:physiology*
D011460:Prostaglandins F; D003995:Dibutyryl Cyclic GMP; D003994:Bucladesine; D012065:Relaxin; D002772:Cholera Toxin; D015237:Dinoprost; D006152:Cyclic GMP; D007545:Isoproterenol