Release of immunoreactive oxytocin and neurophysin I by cultured luteinizing bovine granulosa cells.

We investigated the production of oxytocin (OT) and oxytocin-neurophysin (bNpI) by bovine granulosa cells cultured in presence of 10% foetal calf serum, a condition known to induce spontaneous luteinization of these cells. The production of immunoreactive OT was significantly higher in the cultures of granulosa cells harvested from large follicles than in those derived from small follicles. Chromatography on Sephadex G-25 showed similar elution sites of ovarian and synthetic OT, while high performance liquid chromatography revealed two peaks of OT-immunoreactivity, one of which (+/- 65% of the total immunoreactivity) coincided with synthetic OT. In another experiment, we could observe a gradual increase of OT, bNp I and progesterone production by granulosa cells derived from large follicles, in relation with the incubation time. The mean molar ratio OT: bNp I was 2.2 +/- 0.5 (SEM), and we found a significant positive correlation between the production of OT and bNp I (r = 0.77; P less than 0.01) and between the production of OT and progesterone (r = 0.80; P less than 0.01). Furthermore, the cellular OT and bNp I content of large follicles-derived granulosa cells before culture was 4-5 times lower than the total amount of OT and bNp I produced during a 72-h incubation, suggesting an active synthesis of these peptides. These data show that bovine granulosa cells are able to produce OT and bNp I, probably by an active biosynthesis as observed in the hypothalamo-neurohypophysial system and that the granulosa productions of OT, bNp I and progesterone are closely related.

Increase in ovulation rate after active immunization of sheep with inhibin partially purified from bovine follicular fluid.

Four Romney ewes were actively immunized with a partially purified preparation of inhibin derived from bovine follicular fluid and their ovulation rates in four successive oestrous cycles were compared with those of four ewes receiving adjuvant alone. The ovulation rates of the ewes immunized with the inhibin preparation were significantly higher than those of the control ewes (2.06 +/- 0.16 (S.E.M.) vs 1.31 +/- 0.06 ovulations/ewe, n = 4). Plasma concentrations of FSH and LH, measured in blood samples taken three times a week for 11 weeks, during which time each ewe was immunized three times, were not significantly different between the two treatment groups. These results suggest that active immunization with inhibin-enriched follicular fluid may be a potential means of increasing fecundity in sheep.

Effect of neuraminidase on inhibin activity in vivo and in vitro.

Matrex gel red A purified follicular fluid has been used to study whether or not this material contains sialic acid residues and their importance in maintaining the biological activity of inhibin both in vitro and in vivo. It appears that sialic acid is present in these preparations and can be released either by neuraminidase treatment of acid hydrolysis. The addition of intact and desialylated inhibin-containing material to isolated rat pituitary cells in culture gives similar inhibition of LHRH-induced FSH release of these cells indicating that sialic acid is not required for inhibin activity in vitro. The injection of intact inhibin preparations leads to a reduction of the uterine weight increase seen in immature female mice primed with human chorionic gonadotropin. By contrast, the inhibition of this uterine weight increment by 80% desialylated inhibin-containing material is significantly reduced, suggesting that sialic acid residues play an important role in maintaining the biological activity of inhibin in vivo.

[In vitro incorporation of radioactive sulfur into proteoglycans of cartilage. Effects of various nonsteroidal anti-inflammatory agents]. / Incorporation du soufre radioactif dans les protéoglycanes du cartilage in vitro. Effets de certains anti-inflammatoires non stéroïdiens.

Radioactive sulphur (35SO4) is incorporated in the proteoglycans of chicken embryonic cartilage. In fact, the molecular weight of the macromolecules which bind the sulphur corresponds to monomeric proteoglycans and proteoglycan-hyaluronic acid complexes. This incorporation does not take place when the cartilage has been previously killed. The capture of 35S is stimulated by human serum, in a dose-dependent way. At doses less then, equal to and greater than the maximal plasma concentrations observed following a single oral dose (600 mg), acetyl salicylic acid and sodium salicylate inhibit the incorporation of radioactive sulphur in the cartilage. Under the same conditions, tiaprofenic acid and oxametacine have no effect on this metabolic parameter.

[Purification of prostatic acid phosphatase from human seminal plasma]. / Purification de la phosphatase acide prostatique à partir de plasma séminal humain.

Prostatic acid phosphatase has been isolated from human seminal plasma. The purification method utilizes gel filtration on Sephadex G100, ammonium sulfate precipitation and a series of chromatographical steps including concanavalin A Sepharose 4B, anion exchange and gel filtration chromatography. The final product appears homogenous when analyzed by gel filtration on Sephadex G100. It gives one major band on SDS polyacrylamide gels. The specific activity is similar to that obtained by other purification schemes. The yield of the method described above has allowed to set up a sensitive radioimmunoassay of prostatic acid phosphatase.

[Intracellular mechanism for the action of inhibin on the secretion of the follicular-stimulating hormone and luteinizing hormone induced by LH-RH in vitro]. / Un mécanisme intracellulaire de l'action de l'inhibine sur la sécrétion de l'hormone folliculo-stimulante et de l'hormone lutéinisante induite par le LH-RH in vitro.

The FSH secretion-inhibiting action of inhibin in vitro under basal conditions and also in the presence of LH-RH is suppressed by the addition of MIX, a phosphodiesterase inhibitor. In the presence of LH-RH, inhibin reduces significantly the intracellular level of cAMP in isolated pituitary cells. In contrast, the simultaneous addition of MIX and inhibin raises the cAMP level, and this stimulation is comparable to the increase observed when MIX is added alone. These observations suggest that one mode of action of inhibin could be mediated by a reduction in cAMP within the pituitary gonadotropic cell.