Action Of Gonadotropic Hormones Research Articles

Evaluation of the efficacy of gonadotrophic inductors of ovulation in rats with hyperandrogenemia given flutamide

The objective of the present work was to study the influence of antiandrogen flutamide (flutapharm) at a dose of 1.0 mg/kg b.w., human chorionic gonadotropin (choragon, 5 IU), and folliculostimulating hormone (menopur, 0.01 IU) on the morphofunctional characteristics of ovaries. These products were administered either alone or sequentially to sexually mature female rats after the implantation of testosterone-containing polymeric capsules. The presence of hyperandogenism was confirmed by the five-fold rise in the blood testosterone levels. Analysis of the oestrus cycle, the weight and histological structure of the ovaries gave evidence of disturbed folliculogensis, degenerative changes in follicular epithelium, the development of ovarian polycystosis and anovulatory state in the hyperandrogenic animals. It is concluded neither flutamide nor gonadotrophic hormones administered at the above doses promoted normalization of the generative function of rat ovaries. At the same time, stimulation with gonadotropins following glutamide administration restored folliculogenesis, ovulation, an formation of luteal bodies. The results of this study indicate that flutamide can be used to enhance the stimulating action of gonadotropic hormones on the ovaries in hyperandrogenic individuals.

Protein Kinase A-Independent cAMP Stimulation of Progesterone in a Luteal Cell Model Is Tyrosine Kinase Dependent but Phosphatidylinositol-3-Kinase and Mitogen-Activated Protein Kinase Independent1

Comprehensive understanding of the cellular mechanisms utilized by luteal cells in response to extracellular hormonal signals resulting in the normal synthesis and secretion of their steroid and peptide products has yet to be achieved. Previous studies have established that cAMP functions as a second messenger in mediating gonadotropin stimulated luteal progesterone secretion. Classically, increased intracellular concentrations of cAMP result in activation of protein kinase A (PKA), which in turn phosphorylates gene regulatory transcription factors. Recent studies demonstrate that non-PKA mediated actions of cAMP exist, yet the mechanisms are not well understood. In addition to gonadotropic hormones, such growth factors as insulin, insulin-like growth factor 1, and epidermal growth factor have been shown to modulate luteal steroid hormone synthesis and steroidogenic enzyme expression as either independent effects or via amplification or modulation of the action of gonadotropic hormones or cAMP. Thus, mechanisms independent of cAMP and also downstream to cAMP that do not involve PKA are likely to be important in steroidogenesis in mammalian cells. The present studies were performed to help define the cellular mediators involved in cAMP-stimulated progesterone expression. Our data demonstrate that, in an in vitro steroidogenic cell model, 1) cAMP-stimulated progesterone occurs in a manner that is independent of PKA, 2) neither phosphatidylinositol-3-kinase nor mitogen-activated protein kinase are involved in PKA-independent cAMP-stimulated progesterone production, 3) tyrosine kinase activity does mediate cAMP-stimulated progesterone production, and 4) cAMP directly activates the Ras protein. These data suggest novel mediators of cAMP-stimulated progesterone production.

Inhibition of pituitary gonadotropic effects in the pars distalis-ectomized Rana esculenta by methallibure (ICI 33,828).

Effects of Methallibure on the gonadotropic stimulation of the regressed gonads and secondary sex characters of the pars distalis-ectomized adult green frog, Rana esculenta, were studied. Regression of the gametogenetic activity and reduction of oviducts and thumb pads are the eventual consequences of the removal of pars distalis. Homoplastic pars distalis homogenates restimulate the gametogenesis and regressed secondary sex characters due to their gonadotropic hormone contents. Methallibure in this case blocks the stimulation of these organs by homoplastic pars distalis, which indicates that this compound inhibits the action of gonadotropic hormones upon their target tissues.

Action of Gonadotropic Hormones in Amenorrhea as Evaluated by Vaginal Smears.

SummaryThe desirability of a reclassification of the amenorrheas based, in part, on the vaginal smear picture has been suggested. Definite smear changes indicative of ovarian stimulation and resembling the normal cycle have been induced in amenorrhea by means of gonadotropic hormones. The vaginal smear should afford a simple and sensitive method for evaluating the effects of such hormones in the human subject.

Inhibitory Effects by the Hypophysis of Rats Following Injections of Pregnant Mare Serum Hormone.

ConclusionIt appears that the hypophysis under the influence of estrin, whether supplied by injections or by overstimulated ovaries, actually inhibits possibly through the intermediary of some other endocrine gland the action of gonadotropic hormone.

Biochemical pregnancy detection

The author found that rats not only tolerate large doses of pregnant women's urine well, but are also more sensitive to the action of gonadotropic hormones, so he suggested using Zondek-Aschheim instead of mice infantile rats, which inject pregnant women's urine in the amount of 10-14 cc under the skin of their backs.

Action of Gonadotropic Hormone from Pregnant Mare's Serum on Ovaries of Rhesus Monkeys.

Since the demonstration of Cole and Hart that the blood serum of pregnant mares contains large amounts of gonadotropic hormone, this hormone has been the subject of much investigation. Although the recent work of Catchpole and Lyons indicates a placental origin of the hormone, it has been found to have biological effects similar to those found in the pituitary gland and to differ markedly from the chorionic hormone of human pregnancy. Thus the experiments of Evans, et al., have shown that the hormone of the pregnant mare is able to cause a marked enlargement of the ovaries of hypophysectomized rats, and it has been found to possess a pronounced stimulating effect on the testes and the comb growth of infantile cocks (Hamburger) just like the anterior pituitary hormone, while the gonadotropic hormone from the urine of human pregnancy is ineffective in this respect. The difference between the effects of extracts of human pregnancy urine and extracts of anterior pituitary or from castrate urine on the ovary of the monkey has been previously reported (Engle, Smith and Engle). It has been of interest, therefore, to investigate the effects of an active extract of the serum of pregnant mares on the follicular structure and activity of the ovary of the macacus monkey. Six females, 5 preadolescent and one adult, have been used in this preliminary experiment, the details of which are set forth in Table I. The results have indicated that, regarding the functional activity and structural changes of the ovary of the monkey, the active principle of pregnant mare's serum closely resembles that found in urine of castrate women. The oestral response of the sex skin of the monkey, seen on day 5 or 6 of treatment, is quite similar to that obtained by oestrin, A.P. or C.U. (Allen, Hisaw et al., Engle), and progresses characteristically until the conclusion of treatment after 10 days.

XXIV.—Adrenaline and the Œstrous Cycle in the Mouse

SummaryThe injection of adrenaline hydrochloride into mature female mice is able to inhibit the occurrence of oestrus.The injection of adrenaline hydrochloride into immature female mice prevents the onset of sexual maturity.Adrenaline does not interfere with the action of α-hormone (œstrin) on the uterus and vagina; it has an inhibitory effect on the action of gonadotropic hormones (prepared from pregnancy urine) on the ovary.I should like to thank Mr P. G. Marshall for the supply of gonadotropic preparation from pregnancy urine used in these experiments.