Stimulation of luteinising hormone release by luteinising hormone-releasing hormone in the porcine anterior pituitary: The role of cyclic AMP

Cells dissociated from porcine pituitary glands have been used to examine the relationship between cyclic AMP levels and the stimulation of luteinising hormone (LH) secretion by luteinising hormone-releasing hormone (LHRH). It has been shown that while dibutyryl cyclic AMP and theophylline have a modest and, under some conditions, an inhibitory effect on LH release, the phosphodiesterase inhibitors isobutylmethylxanthine and ICI 63197 both induce LH release and enhance LHRH-induced release. The prostaglandins E₁ and E₂ and cholera toxin, which are shown to raise cyclic AMP levels in the dissociated preparation, also induce LH release and increase LHRH-induced LH release. Finally, LHRH is shown to increase the total content of cyclic AMP in the mixed cell preparation by approximately 30% and it is concluded that, in this system, the nucleotide does play a role in coupling LHRH stimulation to LH release.