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.
A heterologous radioimmunoassay for tammar wallaby FSH, using an ovine FSH antiserum and a human FSH tracer, is described. With this assay concentrations of FSH in plasma of intact female tammars are not detectable except rarely at the time of oestrus. However the assay has proved useful in studies of the control of gonadotrophin secretion in intact male and in ovariectomized tammars. In the female tammar, concentrations of LH and FSH in plasma rose within a few days of bilateral ovariectomy. Ovariectomized tammars respond to a luteinizing hormone releasing hormone stimulus (10 microgram, i.v.) with a prompt release of LH, peak levels of 16.9 +/- 1.4 ng NIH-LH-S19/ml plasma (n = 12) being reached within 25 min of injection. Concentrations of LH and FSH in plasma were reduced to preoperative values in ovariectomized tammars when lutein tissue developed in ovarian cortex grafts autotransplanted under the pouch skin. Ovarian interstitial tissue was not necessary for this effect. After lutectomy during quiescence, the female tammar ovulates again in about 14 days. Injections of progesterone (700 microgram/kg per day, i.m.) for 7 days after the operation did not delay this response, but follicular development and ovulation appeared to be retarded in animals given oestradiol-17 beta (5 microgram/kg per day, i.m.) with or without progesterone.
Summary. Luteal tissue collected from tammars 0, 5, 9 and 16 days after removal of pouch young actively produced progesterone in vitro. On Days 5, 9 and 16 luteal progesterone concentration was not significantly different from Day 0 (quiescence).However, the net production of progesterone was significantly higher on Day 5 (P < 0\m=.\05) than at any other stage, and we suggest that the corpus luteum is the main source of the rise in progesterone in the peripheral circulation at Days 5\p=n-\8of the delayed or non-delayed cycle.Addition of ovine prolactin to corpora lutea incubated on Day 5 after removal of pouch young had no effect on luteal progesterone concentration or the production of progesterone. We therefore conclude that the tonic inhibition exerted by prolactin on the corpus luteum does not affect the steroidogenic capacity of the luteal tissue but may inhibit luteal cell growth during quiescence.
We have devised a new method for the fractionation of human plasma high density lipoprotein (HDL). The HDL was chromatographed on DEAE-agarose columns using a continuous gradient of 0.06--0.15 M NaCl. The elution pattern obtained showed three phases, each with differing peptide composition. Examination of the three subfraction showed that each contained both apoA-I and apo A-II, but in different proportions. Subfraction 1 contained no apo C-II or C-III-1 and only a trace of apo C-III-2, subfraction 2 contained apo C-II and C-III-1 but no C-III-2, while subfraction 3 contained considerable apo C-III-2 with only traces of apo C-II or C-III-1.
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