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Clinique Endocrinologique, C.H.U. La Timone, Marseille 13385, France
(Received 23 September 1975)
Melanocyte-stimulating hormone (MSH) and adrenocorticotrophin (ACTH) release vary independently in the rat following corticosteroid administration or adrenalectomy as shown by bioassay (Kastin, Schally, Viosca & Miller, 1969; Dunn, Kastin, Carrillo & Schally, 1972; Thody & Hinks, 1973) or radioimmunoassay (Usategui, Oliver, Vaudry, Lombardi, Mourre, Rozenberg & Vague, 1975; Usategui, Oliver, Vaudry, Lombardi, Rozenberg & Mourre, 1976) methods. In an attempt to define more clearly the effect of corticosteroids on the release of α-MSH and ACTH, plasma α-MSH and ACTH have been measured after stimulation by haloperidol injection or ether stress in normal as well as in corticosteroid-treated male rats. Immunoreactive α-MSH has been used as an index of MSH activity because α-MSH is thought to be the major MSH in the rat (Baker, 1973; Scott, Lowry, Ratcliffe, Rees & Landon, 1974; Thody, Penny & Clark, 1975).
Adult male
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Polyacrylamide gel electrophoresis has been employed to separate three fractions that have relaxin activity from crude extracts of ovaries of pregnant sows. Bioassays indicated that all fractions had the ability to inhibit spontaneous uterine contractions in vitro and to induce formation of interpubic ligaments in oestrogen-primed mice. The presence of the various fractions in crude extracts of sow ovaries was monitored with the polyacrylamide gel system on days 40, 70 and 100 of pregnancy. Both the total amount and the relative proportions of the fractions were found to change as pregnancy progressed.
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Coffey, Ichinose, Shimazaki & Williams (1968) and Ritter (1966) have demonstrated that 2 weeks after castration the concentration of ATP in the rat ventral prostate remains unchanged from normal levels but that 1 h after testosterone treatment dramatic reductions in ATP concentrations are observed. The cellular site of testosterone action upon ATP metabolism is unknown. In a complex tissue such as the prostate it is difficult, if not impossible, to examine separately the biochemistry of the epithelium and muscle; this can be effectively surmounted using the guinea-pig seminal vesicle. From this, a relatively pure preparation of epithelium can be obtained, and the biochemical sensitivity of these two cell lines may be compared. It is the purpose of this work to examine the effects of castration and testosterone replacement upon the levels of ATP in the epithelium and muscle of the guinea-pig seminal vesicle as well as in the prostate.
Mature,
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Abstract
It has been suggested, but not shown, that in the fetus placental lactogen (PL) may affect the regulation of the IGFs and fetal metabolism. To examine the effects of PL on the circulating concentrations of the IGFs, IGF-binding proteins (IGFBPs), glucose, free fatty acids (FFAs) and amino nitrogen (AN), we infused late gestation sheep fetuses with recombinant ovine PL (roPL). Five chronically-catheterised sheep fetuses were infused intravenously with three 24 h infusions of saline, roPL (100 μg bolus then 500 μg over 24 h) and then saline again.
Fetal roPL infusion increased plasma oPL from 0·4 ± 0·1 to 3·3 ± 0·5 nm (mean ± s.e.m.; P<0·05; factorial analysis of variance and Scheffé's test). Fetal plasma IGF-I, IGF-II, insulin, FFAs and blood glucose were unaffected by the roPL infusion. Fetal plasma IGFBP-3, as measured by Western ligand blotting, decreased by 30% during fetal roPL infusion while other fetal plasma IGFBPs were unaffected. Fetal roPL infusion decreased fetal blood AN from 7·3 ± 0·5 to 6·6 ± 0·2 mm (P<0·05). Maternal plasma IGF-I, IGF-II, IGFBPs, insulin, FFAs, blood glucose and AN were unaffected by the fetal roPL infusion. Saline infusion had no effect on any parameter.
The data suggest that PL is not a significant determinant of plasma IGFs in the late gestation sheep fetus although there may be an indirect effect via alterations in levels of IGFBP-3. The effect of fetal roPL infusion on fetal blood AN concentrations may suggest some role for PL in the regulation of fetal amino acid metabolism.
Journal of Endocrinology (1995) 144, 333–338
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ABSTRACT
Seven Merino–Border Leicester cross–bred ewes were immunized with a purified fusion protein, produced by recombinant DNA methods, of the a subunit of bovine inhibin. Four animals were immunized with the fusion protein alone and three with a conjugate made by coupling the fusion protein to keyhole limpet haemocyanin (KLH) using glutaraldehyde. Each animal received four injections of the fusion protein over 93 days. The animals were synchronized using progestagen sponges and subjected to laparoscopy for the determination of ovulation rates in two consecutive cycles (days 115 and 135). The immunized animals had overall mean ovulation rates for each cycle of 3.4 and 3.4 which was significantly (P < 0.001) above the rates of 1.1 and 1.4 determined for the controls, which had either received no treatment (n=5) or had been immunized with 300 μg KLH (n=4). Analysis of antisera taken on day 115 showed significant fusion protein antibodies and iodinated inhibin–binding capacity in the test but not control groups. Furthermore, antisera to the fusion protein in four out of seven ewes neutralized the inhibin bioactivity of ovine follicular fluid in an in–vitro bioassay. These data demonstrate that neutralization of inhibin can be effected by immunization with bovine inhibin a subunit and that such immunization results in increased ovulation rates as predicted from the biological role of inhibin as a suppressor of FSH.