Vaginocervical stimulation of ovariectomized estradiol-primed ferrets (which a r e 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 (20.50 nglml) before Stimulation, to 2.4k0.43 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 t h e 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 vaginocervical 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 perikarya of stimulated females revealed more Golgi complexeslcell compared to baseline females. W e propose that vaginocervical stimulation also augments the processing of extended precursor forms of LHRH to generate the decapeptide.The neural, chemical and environmental stimuli that regulate the tiniilig of ovulation ultimately transfer information to hypothalanile ncurocndocrine cells, and thereby alter the release of luteinizing hormone-releasing hormone (LHRH). The mechanisms whcrcby these stimuli interact to induce release of LHRH are un6 Tiown. Further. these stimuli may also be important in regulating Lhe biosynthesis or processing of preproLHRH.U u havc recently demonstrated a progressive augmentation in Proloin synthesizing organelles (i.e. rough endoplasmic reticulum, Golgi apparatus and associated vesicles) within LHRH perikarya of civariectomized rats. These morphological alterations within Lf~1ftf-I perikarya occurred as plasma LH levels escalated subxc]clcnt to ovariectomy. Accompanying thesc intraneuronal a h ;Ilions, we observed modifications in synaptic profiles in the net11 Opil surrounding the LHRH perikarya (1). The increases in synaptic profiles also correlated with elevations of plasma LH fOlic)wing ovariectomy in the rat. These findings are consistent With the hypothesis that the signals mediating LHRH release ma!. 4so mediate synthesis/processing of LHRH precursor, generatill! physiologically active decapeptide. -~ ~~In this study we utilized an induced ovulator, the ferret (2-4), to examine alterations that occur within LHRH neurons in response to stimulation leading to elevated plasma LH levels. Carroll and associates ( 5 ) have established that penile intromission is the stimulus that is necessary to induce ovulation in ferrets;...