Dissociation between LH release and pituitary cyclic nucleotide accumulation in response to synthetic LH-releasing hormone in vivo.
In order to clarify the role of cyclic nucleotides in the mediation of LH-releasing hormone (LH-RH) action on LH release, the effect of LH-RH on LH release and pituitary cyclic AMP and cyclic GMP accumulation was studied in vivo. Pituitary cyclic AMP levels were increased 10 min after the intraveneous injection of 2 mg dibutyryl cyclic AMP (db-cyclic AMP) or 25 mg aminophylline. However, serum LH levels were not altered at 10, 30 or 60 min after the administration of either agent. Synthetic LH-RH (100 ng/rat) increased serum LH levels as measured 10 min after injection, but no effect on either pituitary cyclic AMP or cyclic GMP was seen 1, 5 or 10 min after LH-RH administration. These in vivo results are contradictory to the second messenger hypothesis for either cyclic AMP or cyclic GMP in the mediation of LH-RH-induced LH released and suggest that further work must be done in order to confirm or reject this hypothesis.
D000628:Aminophylline / Q000494:pharmacology; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism*; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D010902:Pituitary Gland / Q000378:metabolism*; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D051381:Rats
D000628:Aminophylline; D007987:Gonadotropin-Releasing Hormone; D003994:Bucladesine; D007986:Luteinizing Hormone; D000242:Cyclic AMP; D006152:Cyclic GMP