Macropodid Marsupial Luteinizing Hormone: Validation of Assay Procedures and Changes in Concentrations in Plasma During the Oestrous Cycle in the Female Tammar Wallaby (Macropus Eugenii)

Abstract

A heterologous double antibody radioimmunoassay employing a rabbit anti-ovine LH antiserum (GDN no. 15) has been developed for the assessment of concentrations of LH in macropodid marsupial pituitary extracts and plasma. In this radioimmunoassay system highly purified ovine, rat human and kangaroo LH preparations demonstrated apparently parallel dose-response curves, as did serial dilutions of crude pituitary extracts from a wide range of Austrlian marsupial species and serial dilutions of plasma from ovariectomized, oestrous and LH releasing hormone (LH-RH)-treated marsupials. The assay has been used to monitor changes in immunoreactive LH in the plasma of the female tammar wallaby. Basal concentrations of LH in non-oestrous female wallabies were in the range < 0.20--1.90 ng/ml with many animals having values at or near the limit of detection of the assay. Concentrations of LH were markedly increased following ovariectomy (1.7--7.0 ng/ml), on the day of oestrus (10.0-- > 50 ng/ml) and following administration of LH-RH (9.5-- > 25.0 ng/ml). Plasma from hypophysectomized animals had no detectable LH immunoactivity, A well-defined LH surge, lasting approximately 12 h, was associated with oestrus. Mating occurred approximately 8 h before, and ovulation approximately 24 h after, the maximal concentrations of LH in plasma.

Effects of removal in late pregnancy of the corpus luteum, Graafian follicle or ovaries on plasma progesterone, oestradiol, LH, parturition and post-partum oestrus in the tammar wallaby, Macropus eugenii

“…Associated events all occur within 24 h: the oestradiol peak after 8-3 h, oestrus after 9-8 h, and the LH surge after 15 h. The intervals from progesterone drop to mating and to the LH surge are very similar to the interval from birth to mating of 8 0 h and the interval from birth to LH peak of 160 h reported by Tyndale-Biscoe et al (1983), and the interval from birth to mating is the same as that reported by Shaw & Renfree (1984). The interval from LH surge to ovulation, now shown to be very close to 24 h, refines the estimate of 20-40 h by Sutherland et al (1980).…”

“…Parturition coincides with a transient pulse of prolactin (Hinds & Tyndale-Biscoe, 1982a) and a very rapid decline of progesterone in peripheral plasma from 500 to less than 200 pg/ml (Hinds & Tyndale-Biscoe, 1982b) and is associ¬ ated with a decline in progesterone content of the corpus luteum (CL) of pregnancy (Renfree, Green & Young, 1979). Oestrus and a transient pulse of luteinizing hormone (LH) occur 8 and 16 h, respectively, after parturition (Tyndale-Biscoe, Hinds, Horn & Jenkin, 1983), and ovulation occurs between 20 and 48 h after the LH pulse (Sutherland, Evans & Tyndale-Biscoe, 1980). Tyndale-Biscoe et al (1983) considered that the decline in progesterone might initiate this sequence of events through an alteration of the progesterone:oestrogen ratio, but they were unable to deter¬ mine the role of oestradiol at that time.…”

“…The assay sensitivity was 25 pg/ml and intra-and interassay coefficients of variation were 9% and 13%, respectively. LH was determined by the double-antibody heterologous radioimmunoassay of Niswender, Reichert, Midgley & Nalbandov (1969), validated by Sutherland et al (1980), using ovine antiserum (GDN No. 15) and NIH-LH-S19 for standards.…”

“…The assay sensitivity was 0-3 ng/ml and the intraand interassay coefficients of variation were 6% and 13%, respectively. Because values in intact females are generally below the sensitivity of the assay (Sutherland et al, 1980) (Tables 1 and 2). There¬ fore, hormone values in individual animals were plotted in reference to the time of the first sample in which the progesterone concentration was less than 250 pg/ml (Text-figs 1 & 3).…”

Semen-induced luteal phase and identification of a LH surge in the koala (Phascolarctos cinereus)

“…Comparative studies that characterize LH surge in marsupials are limited to the Tammar wallaby (Macropus eugenii; Sutherland et al 1980), kowari (Dasyuroides byrnie; Fletcher 1983) and brushtail possum (Trichosurus vulpecula;Fletcher and Selwood 2000). In M. eugenii (Sutherland et al 1980), the LH surge occurs 8 h after oestrus and is followed by ovulation 24 -48 h later. Unusually, D. byrnie (Fletcher 1983) females demonstrate a LH peak 12 days before oestrus; its significance to ovulation remains ambiguous.…”