VAGINOCERVICAL STIMULATION OF FERRETS INDUCES RELEASE OF LUTEINIZING-HORMONE-RELEASING HORMONE

Vaginocervical stimulation of ovariectomized estradiol-primed ferrets (which are reflex ovulators) with a glass rod in the presence of a neck-gripping male induced an increase in plasma luteinizing hormone (LH) from undetectable levels (less-than-or-equal-to 0.50 ng/ml) before stimulation, to 2.4 +/- 0.43 ng/ml 75 min after stimulation (stimulated females). Forty-eight h after stimulation plasma LH returned to baseline levels (post-stimulated females). A significant decrease in the number of perikarya containing LH-releasing hormone (LHRH), detected by immunocytochemistry, was associated with the increase in plasma LH following stimulation. Approximately one half of the number of immunoreactive LHRH neurons (243 +/- 27) were detected in the forebrain of stimulated females, compared to those detected in the forebrain of post-stimulated animals (436 +/- 88) using antiserum AR 744. Equivalent results were obtained with a different antiserum (RM 1076) capable of detecting the extended decapeptide, or precursor, as well as partially or fully processed decapeptide. We conclude that controlled vaginocerical stimulation of female ferrets evokes the release of LHRH as well as LH, depleting approximately 50% of the LHRH perikarya of detectable LHRH. Additionally, electron microscopy of LHRH perikrya of stimulated females revealed more Golgi complexes/cell compared to baseline females. We propose that vaginocervical stimulation also augments the processing of extended precursor forms of LHRH to generate the decapeptide.