PARENT SESSION
PLATFORM SESSION 21: REGULATION OF GONADOTROPINS AND THEIR RECEPTORS: II
Chair: LaBarberra, Andrew¹, ¹
Co-chair: Meehan, Thomas¹, ¹
Harborside D
2:00 PM-4:00 PM

(449) CHARACTERIZATION OF THE ROLE OF FSH IN THE MARMOSET MONKEY: COMPARISON OF FSH LEVELS IN NATURAL CYCLES, PROSTAGLANDIN-F₂-REGULATED CYCLES, AND SOCIALLY SUBORDINATE ANIMALS.

Gilchrist, Robert¹, Pritchard, Lottie¹, Amato, Fred¹, Ritter, Lesley¹, Armstrong, David¹, Norman, Robert¹, ¹ Reproductive Medicine Unit, Department of Obstetrics and Gynaecology, Adelaide, Australia

ABSTRACT- Even though the common marmoset is an important non-human primate laboratory model in reproductive biology, lack of specific antibodies and sensitive assays to measure marmoset FSH means the role and regulation of this key hormone remains poorly understood in this animal. We have recently produced bioactive recombinant marmoset FSH (r-mFSH), and developed a sensitive and specific RIA for measurement of urinary mFSH using a polyclonal anti-r-mFSH antibody. This study utilised this assay to examine the role of FSH in natural and prostaglandin F₂(PGF) regulated cycles, and in acyclic socially subordinate females. Daily samples of urine for FSH and blood for progesterone measurement were collected for 17 complete PGF regulated cycles and for 8 natural cycles. Samples were also collected from 5 adult females maintained under a natural condition of social subordination (acyclic) by housing with a dominant female, and during the transition phase from subordination to cycling induced by removal from the dominant female. Both PGF-regulated and natural cycles showed a general pattern of an early follicular phase rise in FSH and a preovulatory peak (P<0.001), with low late follicular and luteal phase FSH levels. The 4 day early follicular phase rise, which in PGF-regulated cycles occurred within 24h of PGF treatment, reached levels ~90% of the preovulatory peak (P>0.05). This high FSH which, relative to the preovulatory peak, is much higher than in other primates, and may play a role in the recruitment of multiple follicles typical of this species. The overall FSH profile did not differ between PGF-regulated and natural cycles. Subordinate FSH levels (5.3±0.47 ng FSH/mg creatinine; mean ±SEM) were on average 2.7-fold higher (P<0.001) than average cycling FSH levels (2.0±0.23) and were comparable (P>0.05) to preovulatory peak levels (3.3±1.24). With removal of social subordination, FSH levels dropped (P<0.001) within 24h to basal levels with ovulation following 11 days later (progesterone >32 nmol/l). Development of an assay for marmoset FSH has revealed that subordinate animals are not hypogonadotrophic as previously thought. Normal GnRH release, high FSH and very low LH, suggests that social subordination may operate by acute neuroparacrine suppression specifically of LH leading to ovarian acyclicity.

KEY WORDS: follicle stimulating hormone , common marmoset monkey, social subordination, ovarian cycle