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- Author: E. V. YOUNGLAI x
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ABSTRACT
Peripheral serum concentrations of LH, FSH and prolactin were determined by radioimmunoassay on different days after birth in the female rabbit. Serum cholesterol concentrations were also analysed by a colorimetric method. Concentrations of serum LH and FSH showed two distinct peaks occurring on day 9 (LH, 4·05 ± 0·76 (mean ± s.e.m.) μg/l; FSH, 3·62 ± 0·67 μg/l) and either day 35 (LH, 5·90 ± 1·20 μg/l) or day 40 (FSH, 9·01 ± 1·43 μg/l). Concentrations of LH and FSH were in the adult range (LH, < 1 μg/l; FSH, < 0·6 μg/l) by day 100. Serum prolactin showed a progressive increase from day 1 (1·04 ± 0·07 μg/l) to day 100 ( 17·30 ± 2·50 μg/l) with a peak on day 40. Total serum cholesterol in another series of rabbits was high from days 1 to 22 (7·53 ± 0·64 mmol/l) and then decreased to 1·94–3·36 mmol/l by day 106. These data indicate that the two major developmental peaks in gonadotrophins may be related to ovarian function.
J. Endocr. (1986) 109, 287–290
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SUMMARY
The rapidity of binding of LH to rabbit ovarian follicles was examined using androgen production as the endpoint. Incubations were carried out for about 8 h with medium being changed every 15 min except during the periods when follicles were exposed to LH and/or anti-LH and subsequent washing. Exposure of follicles to LH for 1 s followed by washing in (a) LH-free medium, (b) pure anti-LH or (c) diluted anti-LH, failed to inhibit androgen production which persisted for more than 2 h. Simultaneous addition of anti-LH and LH to the medium before incubation with follicles completely inhibited the response though it could be elicited from the same follicles when LH was added later. These data suggest that the binding of LH to follicular receptors is a rapid process and that either the LH-receptor complex is very stable or that LH initiates a series of reactions which are independent of the presence of hormone.
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Samples of human amniotic fluid were obtained by amniocentesis prior to delivery and stored at −15 °C until analysed for 17β-hydroxyandrogens. Conjugated androgens were hydrolysed by boiling with concentrated hydrochloric acid and the free steroids extracted with diethyl ether. The dried extracts were then subjected to radioimmunoassay by the technique of Chen, Zorn, Hallberg & Wieland (1971), except that dextran-coated charcoal was used to separate the free testosterone. Since the antiserum (kindly donated by Dr M. C. Hallberg, Cleveland) was prepared against testosterone-3-bovine serum albumin and it cross-reacted significantly only with 17β-hydroxy-5α-androstan-3-one, the method must be considered as measuring total immunoreactive 17β-hydroxyandrogens though testosterone is probably the major one present. Comparison of this method with a protein-binding method for testosterone involving a prior chromatographic step, gave a correlation coefficient, r, of 0·973. Other steroids are therefore not likely to contribute to the estimation of 17β-hydroxyandrogens. Water and solvent blanks were
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Department of Obstetrics and Gynecology, Programme in Reproductive Biology, McMaster University, Health Sciences Centre, Hamilton, Ontario, Canada, L8S 4J9
(Received 23 April 1976)
In a previous communication it was observed that luteinizing hormone (LH) (10 μg/ml) had no effect on oestradiol production by rabbit follicles while testosterone production was greatly increased (YoungLai, 1974). In the same study lower concentrations of LH (1 and 10 ng/ml) appeared to stimulate oestrogen secretion. Whereas Mills, Davies & Savard (1971) showed that the rabbit follicle is extremely sensitive to LH, with good incorporation of [14C] acetate to oestrogens, Moor (1974) demonstrated that high levels of LH inhibit aromatization in sheep follicles. On the other hand, Ryle, Court, Smith & Morris (1975) found that immature mouse ovaries can produce oestrogen in the presence of LH and follicle-stimulating hormone (FSH), alone and in combination. Equine granulosa cells can aromatize testosterone to oestrogens in the presence of
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SUMMARY
Follicular fluid from individual follicles was collected from nine mares in oestrus and the concentration of the following steroids determined by gas—liquid chromatography: progesterone, 17α-hydroxyprogesterone, androstenedione, 19-norandrostenedione, epitestosterone, oestrone and oestradiol. The most vascular follicles, which were probably those destined to ovulate, tended to have the highest steroid concentrations. In these vascular follicles oestradiol was the main steroid found with an average concentration of 151 μg/100 ml.
In two out of three samples of follicular fluid taken from the mares with recent ovulations, oestradiol was present in large quantities. The corpora lutea from these mares contained the following steroids: progesterone (average: 1973 μg/100 g), 17α-hydroxyprogesterone (average: 65 μg/100 g), 20α-dihydroprogesterone (average: 249 μg/100g), pregnenolone (average: 33 μg/100 g). Pregnenolone was not detected in any of the samples of follicular fluid examined.
A pool of eight mid-cycle corpora lutea contained the same four steroids as those in newly formed corpora lutea but, in addition, oestradiol was detected in the order of 4 μg/100 g.
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The effects of in-vivo administration of progesterone, testosterone propionate (TP) and oestradiol benzoate (OB) on steroid accumulation by isolated rabbit ovarian follicles were examined. Progesterone administration led to a suppression of follicular androgen accumulation when compared to controls injected with sesame oil. Follicles from these rabbits, when stimulated with LH, produced significant amounts of androgens. Administration of TP resulted in an increase in peripheral serum concentrations of progestins and a decrease in serum oestrogens. The follicles obtained after this treatment accumulated significantly less androgen and oestrogen than those from oil-injected rabbits. The response to LH by these follicles was similar to that of follicles from oil-treated rabbits in that significant increases were observed in progestin and androgen accumulation. Follicles from rabbits treated with OB accumulated more progestins and oestrogens than those from oil-treated animals. It is concluded that the hormonal environment of follicles can have profound effects on the subsequent response of follicles to further stimulation and activity, and that steroid treatment can influence the subsequent formation of that particular steroid.
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SUMMARY
Follicles were isolated from rabbits before and after mating and the effects of LH on steroidogenesis were studied using an incubation technique. Before mating testosterone was the major steroid produced in response to LH. Mating or administration of ovine LH in vivo caused the follicles to produce mainly progesterone and these follicles were refractory to LH in vitro. Up to 72 h after mating, LH would stimulate follicles to produce progesterone. At 96 h after mating, the testosterone response to LH was again manifest. These results suggest that the responsiveness of rabbit follicles to LH is dependent on the endocrine status of the animal when the ovaries were removed.
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SUMMARY
Two mares were operated on during oestrus; in the first animal a mixture of [16-3H]pregnenolone and [4-14C]androstenedione was injected into the largest Graafian follicle; in the second animal, [4-14C]pregnenolone and [7-3H]androstenedione were injected into the follicle. By cannulating the ovarian veins it was possible to measure the rate of transfer of radioactivity from the follicular fluid into the ovarian vein. This ranged from 3 to 9% of the injected dose per hour. At the end of each experiment, 45–52 min. after the injection of the labelled precursors, the follicular fluid was aspirated. Negligible amounts of radioactivity were recovered from the rest of the ovary and from the 'conjugated' fraction of the ovarian vein plasma and follicular fluid. Within the follicle 6·2 and 12·2% of the injected pregnenolone were converted to progesterone. Further metabolism to 17 α-hydroxyprogesterone, androstenedione and oestradiol-17β was very limited. Oestradiol-17β isolated from the ovarian vein had a higher specific activity than that from the follicular fluid while the 3H: 14C ratios were similar in both compartments. In addition, the 3H:14C ratios of androstenedione and oestradiol-17β in the ovarian vein were similar. Therefore it seems likely that oestradiol-17β in the follicular fluid is derived mainly from an extra-follicular source, probably the theca interna cells.
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Department of Obstetrics and Gynecology, McMaster University Medical Centre, Hamilton, Ontario, Canada, L8S 4J9, *Department of Medicine, Emory School of Medicine, Atlanta, Georgia 30303, U.S.A. and †Yerkes Regional Primate Center, Atlanta, Georgia 30322, U.S.A.
(Received 26 April 1977)
It is becoming evident that rodents and rhesus monkeys are not suitable models for the study of all aspects of human reproductive endocrinology (Hobson, Coulston, Faiman, Winter & Reyes, 1976). Apes, on the other hand, closely resemble man in many aspects of their endocrinology (Graham, 1976). As part of a continuing study on progesterone metabolism among the great apes, we have found that the single most abundant urinary metabolite of progesterone is 5β-pregnane-3α,20α-diol (pregnanediol) in the adult female chimpanzee (YoungLai, Graham & Collins, 1975) and is similar to that in the immature chimpanzee (Romanoff, Grace, Sugarman & Pincus, 1963). This is in contrast to the macaques where androsterone is the major metabolite
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Peripheral plasma samples were obtained during pro-oestrus and oestrus from two adult Beagle bitches and from one animal (bitch 124) during its first oestrous cycle. The animals were housed in a constant environment kennel and each showed a normal oestrous cycle as judged by clinical appearance, vaginal cytology and behavioural tests; in addition, a rise in plasma progesterone was noted during late oestrus and early metoestrus (Christie, Bell, Horth & Palmer 1971). Plasma oestrogens were measured by the radioimmunoassay technique of Abraham (1969), with modifications. No separation of oestradiol and oestrone was undertaken and the results are thus an estimate of total immunoreactive oestrogens. The water blank for the method was 16 ± 6·5 (s.d.) pg/ml while the solvent blank was 19 ± 4·7 pg/ml. The results were corrected for the solvent blank. The recovery of oestradiol added to water was 102 ± 12 (s.d.)%, and to plasma from a bilaterally ovariectomized, hemi-adrenalectomized
