cAMP augmentation of secretagogue-induced luteinizing hormone secretion.
Whether adenosine 3',5'-cyclic monophosphate (cAMP) acts as a mediator for luteinizing hormone-releasing hormone (LHRH) in either its immediate LH release action or in its self-priming action was investigated. Pituitary pieces from either proestrous or estrous rats were superfused in vitro in the presence of dibutyryl cAMP [(Bu)2cAMP], 8-bromo-cAMP (8BrcAMP), forskolin, or control for 2-3 h. For proestrous but not estrous pituitary pieces, a slight increase in base-line LH secretion rate occurred at approximately 70 min of exposure to elevated cAMP; in the same system LHRH caused an increase in LH secretory rate within 2 min in either proestrous or estrous tissue. In contrast to its ineffectiveness as a secretagogue, cAMP elevation resulted in a severalfold augmentation of both LHRH- and elevated K+-induced LH secretion from proestrous but not estrous pituitary pieces; for these experiments, superfusion with a cAMP analogue or forskolin for varying times preceded a 10-min pulse of either 8 nM LHRH or 47 mM K+. Augmentation was evident after 30 min of cAMP elevation; longer exposures were coincident with greater potentiation. Cycloheximide prevented (Bu)2cAMP augmentation of LHRH-induced secretion. These data show that cAMP does not mediate the immediate LH release action of LHRH, but cAMP does augment LHRH- or K+-induced LH secretion with characteristics in common with the self-priming action of LHRH.
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000494:pharmacology*; D003513:Cycloheximide / Q000494:pharmacology; D004971:Estrus; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000378:metabolism*; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology; D011359:Proestrus; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D007987:Gonadotropin-Releasing Hormone; D003994:Bucladesine; D007986:Luteinizing Hormone; D003513:Cycloheximide; D000242:Cyclic AMP; D011188:Potassium