Changes of urinary steroid conjugates and gonadotropin excretion in the menstrual cycle and pregnancy in the Yunnan snub-nosed monkey (Rhinopithecus bieti)

The Yunnan snub-nosed monkey (Rhinopithecus bieti) is one of the most endan gered species in the world, and it is endemic to China. According to our kn owledge, there was no information on reproduction for this species. The pre sent study was designed to understand the characteristics of reproductive h ormone secretion during the menstrual cycle and pregnancy of this species b y monitoring urinary estrone conjugate (E1C), pregnanediol-3-glucuronide (P dG), bioactive follicle-stimulating hormone (FSH), and luteinizing hormone (LH). The urine samples were collected each day from four adult females for eight menstrual cycles, and once in 3 days during pregnancy (three full-te rm pregnancies, one mid-term abortion). The steroid conjugate was tested by radioimmunoassays (RIAs), and bioactive FSH and LH levels were measured in vitro by the sensitive bioassays granulosa cell aromatize bioassay (GAB) a nd rat interstitial cell testosterone (RICT), respectively. The results sho wed that: 1) E1C presented a preovulatory peak (183.9 +/- 8.6 ng/mgCr) foll owed by a definite elevation of PdG; 2) PdG in the luteal phase (754.4 +/- 30.6 ng/mgCr) was three- to fivefold higher than during the corresponding f ollicular phase (198.3 +/- 11.4 ng/mgCr); 3) the peaks of bio-LH and bio-FS H were on the same day, while the E1C peak was 1 or 2 days before the peaks for these two hormones; 4) bio-FSH levels were higher in the follicular ph ase than in the luteal phase, and bio-LH levels elevated slightly in the lu teal phase; 5) the mean cycle length was 23.6 +/- 3.5 days (n = 3) based up on successive urinary LH peaks; 6) based on the interval from the day of E1 C peak to the day of parturition, the gestation was 203.7 +/- 2.5 days (n = 3); and 7) both E1C and PdG increased and remained high after pregnancy, w ith a sharp decrease in basal levels following parturition or mid-term abor tion. The results suggested that the pattern of reproductive hormones for R . bieti is similar to that of other Old World monkeys, but the concentratio n of the hormones is different from that of other species. This species has a longer progestation period, which may be related to its classification s tatus. (C) 2001 Wiley-Liss, Inc.