Objectives To identify the hypothalamic mechanisms mediating the suppression of ovulation in subordinate female marmoset by push-pull perfusion monitoring of neurotransmitter release in the pituitary stalk-median eminence. Abstract Socially subordinate female marmosets fail to ovulate because of suppressed gonadotropin secretion, presumably caused by reduced hypothalamic release of gonadotropin-releasing hormone (GnRH). Having successfully developed a push-pull perfusion technique to characterize GnRH release in conscious female marmosets, we found surprisingly little evidence for suppressed hypothalamic GnRH release in otherwise hypogonadotropic, hypoestrogenic, anovulatory subordinates. It therefore became clear that we needed to initiate a study to simultaneously measure the release of hypothalamic GnRH and anterior pituitary luteinizing hormone (LH) every 10 minutes for 6-7 hours, in order to clarify the relationship between GnRH and LH release in reproductively suppressed, subordinate female marmosets. We validated a radioimmunoassay for measuring LH in marmosets and a jugular catheterization technique which permitted reliable blood sampling of marmosets every 10 minutes in conjunction with simultaneous hypothalamic push-pull perfusion. Initial results from two ovariectomized females and one intact subordinate female indicated that LH appeared to be released in conjunction with GnRH in the ovariectomized females, whereas, in the subordinate female, circulating LH levels remained below the assay sensitivity limit (0.2ng/ml) despite apparent dynamic release of GnRH. A possible dissociation between GnRH and LH activity in anovulatory subordinate female marmosets requires further investigation. Such studies have important potential for our understanding of hypothalamic mechanisms regulating ovulation in non-human primates and humans. Key words dominance, infertility, hypothalamus, gonadotropin-releasing hormone, luteinizing hormone, push-pull perfusion.
Showing the most recent 10 out of 528 publications
