MEASUREMENT OF FECAL STEROIDS FOR MONITORING OVARIAN-FUNCTION IN NEW-WORLD PRIMATES, CALLITRICHIDAE

Measurement of immunoreactive progesterone, pregnanediol and oestradio l in faeces collected throughout ovarian cycles in three species of ca llitrichid primates is reported. Faecal hormone concentrations were co mpared with plasma progesterone profiles during PGF2alpha-controlled ( n = 7) and natural (n = 8) cycles in Callithrix jacchus and Saguinus f uscicollis, respectively, and with urinary oestrone conjugates during five cycles in Saguinus oedipus. Unconjugated steroids, which predomin ated over enzyme hydrolysable conjugates in samples from all species, were used to generate cycle profiles. According to results from HPLC, oestrone and oestradiol accounted for virtually all oestrogen immunore activity, and oestradiol most often predominated, whereas large amount s of nonspecific immunoreactivity were detected by both progesterone a nd pregnanediol assays. Faecal progestins were excreted in a cyclic ma nner in all species; luteal phase values were on average five- to tenf old higher than corresponding follicular phase values. Significant inc reases in mean amounts of faecal progestins were seen within 48 h of t he post-ovulatory rise in plasma progesterone. Although a similar tren d was also seen for faecal oestradiol, a clear and consistent luteal p hase increase was seen only in Callithrix jacchus and this generally o ccurred later than that of progestins. The results indicate that faeca l progestin analysis provides a useful method for noninvasive reproduc tive assessment in callitrichid primates. In particular, measurement o f immunoreactive pregnanediol enables a multispecies application of a single assay methodology for comparative studies on callitrichid repro ductive function.