Determination of ovarian cycle in Goeldi's monkey (Callimico goeldii) via the measurement of steroids and peptides in plasma and urine

Abstract

Goeldi's monkey (Callimico goeldii) is an endangered species of New World primate. The present study provides the first description of the non-conception ovarian cycle in this species based on circulating reproductive steroid and peptide hormones. The data obtained were used to validate a non-invasive system for monitoring cyclicity based on urinary reproductive steroid metabolites. Nine sexually mature females were studied. In three females, matched blood and urine samples were collected once every 2-3 days for 90-120 days; in three other females, matched blood and urine samples were collected daily for 14-20 days for one peri-ovulatory period; and in the remaining three females, urine samples only were collected once every 1-3 days for 40-60 days. Plasma progesterone, oestrone-3-conjugates and bioactive LH were measured, in addition to urinary pregnanediol-3α-glucuronide and oestrone-3-conjugates. The mean maximum concentration of plasma LH occurred 1-2 days before a significant rise in plasma progesterone, which was considered to occur I day after ovulation. On the basis of plasma progesterone titres, the duration of the ovarian cycle was estimated as 23.9 ± 0.4 days (n = 9), and constituted a follicular phase of 10.7 ± 0.3 days and a luteal phase of 13.5 ± 0.3 days. Urinary pregnanediol-3α-glucuronide demonstrated a high correlation with plasma progesterone (r = 0.8), and demonstrated a significant rise at the same time as plasma progesterone. Application of this urinary progesterone metabolite to determine whether a female was in a follicular phase (pregnanediol-3α-glucuronide < 0.20 μg mg-1 creatinine) or a luteal phase (pregnanediol-3α-glucuronide > 0.20 μg mg -1 creatinine) provided an accurate and reliable non-invasive system for monitoring reproductive state and timing ovulation in this endangered primate. Urinary oestrone-3-conjugates were less accurate and reliable than pregnanediol-3α-glucuronide: while plasma and urinary oestrone-3-conjugates were generally higher during the luteal phase than during the follicular phase, a marked increase in their concentration did not occur until 3-5 days after inferred ovulation.