Studies on reproductive endocrinology in non-human primates: Application of non-invasive methods

Abstract

A practical method for the quantitative measurement of estrone conjugates (E1C), pregnanediol-3-glucronide (PdG), follicle stimulating hormone (FSH), and monkey chorionic gonadotropin (mCG) in the excreta of non-human primates were described. In the series of studies, results suggest that 1) urinary and fecal steroid metabolites accurately reflected the same ovarian or testicular events as observed in plasma steroid profiles in captive Japanese macaques, time lags associated with fecal measurements were one day after appearance in urine; 2) these noninvasive methods were applicable to wild and free-ranging macaques for determining reproductive status; 3) hormonal changes during menstrual cycles and pregnancy could be analyzed by measurement of FSH, CG and steroid metabolites in the excreta in captive great apes and macaques; and 4) hormone-behavior relationships of macaques in their natural habitats and social setting could be analyzed. In macaques, between maternal rejection and excreted estrogen, but not excreted progesterone were associated, moreover, in male study, significantly higher levels of fecal cortisol were observed in high-ranking males. In addition, reliable noninstrumented enzyme-linked immunosorbent assay (NELISA) for detection of early pregnancy in macaques was established. These results suggest that the noninvasive characteristic of excreted hormone monitoring provide a stress-free approach to the accurate evaluation of reproductive status in primates.