Adrenalectomy,ovarian HCG-binding and the onset of female puberty in the rat

Summary The delay of puberty onset in female rats adrenalectomized before the 25th day of age is due neither to changes in the number of ovarian HCG-receptors nor to an altered hormone affinity of these receptors. It is assumed that glucocorticoids act on an intracellular level, in the ovarian cells, possibly by alterations of cyclic AMP-dependent phosphodiesterase activity.This work was supported in part by the Deutsche Forschungsgemeinschaft (SFB 46). Purified HCG was a gift of Schering AG, Berlin-West. We thank Mrs Margarete Lindig for assistance and Mrs Ursula Frigewski for secretarial help.     

Influence of an injection of chorionic hormone (HCG) on the accumulation of testicular fluid following ligature of the vas deferens in adult Wistar rats]

Using the weight gain of the testis after efferent duct ligation, we have measured the testis fluid secretion. A single injection of HCG to Rats before, at the time or after the ligation leads to three types of effects: no effect which can be explained by the metabolisation of the hormone: a positive and/or a negative one. If the stimulating action of HCG remains unexplained, it must be related with ether anaesthesia. It seems likely that the decrease of testicular fluid secretion may represent the fundamental action of HCG upon the exocrine function of the testis, but the mecanism by which this action occurs remains to be solved.     

Reappearance of HCG-receptors in immature rat ovary after HCG-treatment is not due to receptor synthesis

Summary In 24-day-old rats the reappearance of ovarian HCG-receptors after the injection of 200 IU HCG is independent of protein synthesis. The reutilization of occupied receptors in immature female rats is due to dissociation of the receptor-hormone complex.This work was supported in part by the Deutsche Forschungsgemeinschaft (SFB 46). Purified HCG was a gift of Schering AG, Berlin West. We thank Mrs Margarete Lindig and Mrs Rita Rudolph for assistance and Mr A. Schlegel for radioimmunological determinations.     

Relationship of ornithine decarboxylase activity to HCG induced androgen production by rabbit testis

Summary In the rabbit testicular ornithine decarboxylase activity and androgen content as well as serum androgens were increased 4 h after the injection of HCG. D,L-a-difluoromethylornithine (a-DFMO) alone or together with HCG inhibited enzyme activity although testicular and serum androgens were significantly increased aftera-DFMO and HCG. These data suggest that ODC activity is not required for testicular androgen production.This work was supported by the Medical Research Council of Canada, MT 4192.     

Demonstration of testosterone secretion by testicular tissue of hypophysectomized boar as affected by HCG in organ culture]

Boar Leydig cells undergo a strong atrophy from 1 to 3 months after hypophysectomy but can be reactivated by the gonadotropin HCG in organ culture conditions. This reactivation which appeared at histological and ultrastructural level was evidenced by the capacity of testicular tissue to synthesize testosterone as judged by radioimmunoassay. Both synthesis in the tissue and release into the medium increased according the incubation time with HCG; the adjonction of 17 alpha-OH-pregneolone to culture medium led to increase the intra and extra-tissular concentration of testosterone.     

Radioimmunoassay of an invertebrate peptide hormone — the crustacean neurosecretory hyperglycemic hormone

Summary Antibodies against hyperglycemic hormone (CHH) ofCarcinus were raised in rabbits by injection of extract from sinus glands which contain high concentrations of CHH. The antiserum neutralizes the biological activity of CHH and binds¹²⁵J-CHH. A RIA for CHH was established and was used to measure the hormone content of sinus glands.Dedicated to Prof. M. Gersch, Jena, on the occasion of his 70th birthday.This study was supported by the Deutsche Forschungsgemeinschaft (Ke 206/2).We thank S. Grabig. E. schmid and B. Reichwein for expert technical assistance, and Dr D. Breitig and G. Kegel for critical discussions.     

Infertility of the hamster oocyte having matured in vitro]

The comparative study of fertilization, with the same sperm sample, of in vitro matured oocytes and freshly ovulated ones, shows a new aspect of mammalian oocyte maturation. While 80% of freshly ovulated oocytes are fertilized, in vitro matured eggs are not fertilizable. They present the ability to be penetrated by spermatozoa 4 to 6 hrs. only after HCG injection. This is therefore not on tubal influence but depends on an oocyte specific factor which appears during the end of intrafollicular maturation.     

The specificity of binding of glycoprotein hormones to their receptors

The glycoprotein hormone receptor family is peculiar because, in contrast to other G protein-coupled receptors, a large N-terminal extracellular ectodomain is responsible for hormone recognition. Hormone-receptor pairs have evolved in such a manner that a limited number of positions both at the 'seat-belt' domain of the hormone and the leucine-rich repeats of the receptor, play attractive and repulsive interactions for binding and specificity, respectively. Surprisingly, the constitutive activity of the receptor, mostly modulated by highly conserved amino acids within the heptahelical domain of the receptor (i.e., outside the hormone binding region), also regulates effectiveness of hormone recognition by the extracellular part. In this review we analyze, at the molecular level, these important discriminating determinants for selective binding of glycoprotein hormones to their receptors, as well as natural mutations, observed in patients with gestational hyperthyroidism or ovarian hyperstimulation syndrome, that modify the selectivity of binding.     

Ovulation and the role of the ovarian surface epithelium.

Epon sections from all tissue layers of the rabbit ovary, including the often neglected surface or germinal epithelium, were studied to elucidate the mechanism of follicle rupture. Scanning electron microscopy showed cells covering preovulatory follicles increased clearly in size up to 8 hours after human chorionic gonadotropin (HCG) injection. These showed an increasing number of large, intracellular structures with prominent rounded contours. Transmission electron microscopy showed large, electron dense, lysosomelike bodies in some cells 4 hours after HCG. These membrane-surrounded structures increased in size up to 8 hours after HCG, then decreased markedly. These obviously corresponded to the bodies found by light microscopy and scanning electron microscopy. Histochemistry revealed many represent lysosomes. During the last 2 hours before rupture, the dense bodies of the surface epithelium considerably decrease, signs of material emptying into vacuoles is found, and sometimes there is open communication from vacuoles towards the unerlying tunica albuginea. An extracellular edema appeared under the epithelium with degenerated fibroblasts and disintegrated collagen; these changes gradually proceeded inwards. Blood capillaries close to the membrana granulosa gradually showed small pores and close to ovulation the endothelial cells had gaps up to 3 mcm in diameter. The preovulatory follicles grew rapidly and an augmenting edema occupied the whole ovary. In the last hours before ovulation the membrana granulosa gradually dissociated. Whatever the net effect of the prostaglandins, prostaglandin F2alpha appears to be essential for follicle rupture since intrafollicular injections of antiserum blocked ovulation. Prostaglandin E1 promotes vascular permeability and lysosommal enzymes released extracellularly may be coupled to collagen degration. The enzyme synthesis and lysosomal growth in the surface epithelium of preovulatory follicles may be due to the high local concentration of sex steroids.     

Ecdysteroid-dependent larval-adult oviduct transformation in the milkweed bugOncopeltus fasciatus requires absence of juvenile hormone

Summary It has been tested whether juvenile hormone plays a role in the larval-adult transformation of lateral oviducts in the milkweed bug. The transformation is ecdysteroid-dependent, as was reported previously². Application of precocene or juvenile hormone III proved that the absence of juvenile hormone is required.Acknowledgments. This work was supported by a grant (Do 163/91) of the DFG. We thank Ms C. Friederichs for excellent technical support.     

Inhibition of human chlorionic gonadotrophin-induced ovarian and uterine growth in the mouse by synthetic arginine vasotocin-1.

21-day-old Swiss-Webster female mice were injected with 1 IU HCG at 09.00 h. Injection of freshly prepared arginine vasotocin (2 mug/0.1 ml/injection) every 12 h inhibited the HCG-induced hypertrophy of the ovaries at 36, 48, 60 and 72 hr after HCG-treatment while the uterine weight was depressed at 60 and 72 h.     

Precocene-induced metamorphosis in the desert locustSchistocerca gregaria

Summary 50–100% of the 2nd, 3rd and 4th instar nymphs ofSchistocerca gregaria exposed to precocene 2 by contact method metamorphosed precociously from the instar treated. The corpora allata of the precocious adults were degenerate. Topical application of a juvenile hormone analogue (ZR-512) induced in the precocious adults the colouration characteristic of sexually mature adults.This research was supported by the N.S.E.R.C. grant No.A4669.We thank Dr G. B. Staal, Zoecon Corporation, Palo Alto, California, for the generous gift of precocene 2 and ZR-512, M. Hota for rearing the insects, R. G. Long, for the photographs, and Jann Aitken for technical assistance.     

In vitro inactivation of gonadotropin receptors,a membrane-associated action?

Summary Under in vitro conditions the time-dependent inactivation process of LH/HCG receptors is nearly identical in ovarian and testicular homogenates but different in gonadal membrane preparations. In the ovarian membranes the loss of binding sites during the first preincubation time is faster than in testicular membranes, especially in membranes of luteinized rat ovaries. Compared with the homogenates, however, the receptor-inactivation in the membranes is generally delayed. The inhibitory effect of metabolic agents on receptor inactivation indicates that membrane-associated actions are involved in this process.This work was supported in part by the Deutsche Forschungsgemeinschaft (Si 185/2). We thank Mrs Rita Rudolph for skilful technical assistance.     

Reappearance of HCG-receptors in immature rat ovary after HCG-treatment is not due to receptor synthesis.

In 24-day-old rats the reappearance of ovarian HCG-receptors after the injection of 200 IU HCG in independent of protein synthesis. The reutilization of occupied receptors in immature female rats is due to dissociation of the receptor-hormone complex.     

Effect of age,ambient temperature,and exposure to hormone on the posteclosion diuretic response of the monarch butterfly

Summary The monarch butterfly loses sensitivity to the posteclosion diuretic hormone of this species within 12 h of eclosion. This de-sensitization can be accelerated by exposure to the diuretic hormone, and decelerated by both hormone deficiency and reduced temperature.     

The effect of gonadotropic hormones and the fetal hypophysis on testosterone production by the testis of 18 day mouse fetuses in organ culture]

The production of testosterone (measured by radioimmuno-assay) by the 18-day-old mouse fetal testis may be stimulated specifically by ovine LH (1 ng, p less than 0.005) and HCG in organ culture. A stimulation by FSH is observed only with high doses (10 mug, p less than 0.0005). Prolactin and ACTH have no effect. Age-matched fetal pituitaries increase significantly the testosterone production in the culture medium (p less than 0.0005).     

Influence of testicular fluid, spermatozoa and androgens on physiological activity of rat epididymis]

By ligation of the efferent duct and the corpus epididymis, the GPC concentration in this delimited anterior region decreased. However, HCG infection increased the GPC concentration. When spermatozoa are present in the epididymal tubule there is always a decrease in GPC concentration in these experimental conditions. Activity of the epididymis is disturbed by ligation.     

A dialysis rate method for the measurement of free iodothyronine and steroid hormones in blood

From the dialysis rate of a small amount of tracer hormone from a serum sample through a semipermeable membrane towards an identical serum sample, the free hormone fraction can be calculated. This method is free from a number of artefacts that may occur in equilibrium dialysis.     

Plurihormonality in the secretory granules of the normal human pituitary. An immunoelectron microscopic study

Normal human autopsy anterior pituitary tissue from 5 cases was embedded in LR White resin and immunolabelled using silver-enhanced 5-nm protein A gold probes. Follicle stimulating hormone (FSH), thyroid stimulating hormone (TSH), luteinizing hormone (LH), adrenocorticotrophic hormone (ACTH), growth hormone (GH) and prolactin (PRL) were immunolocalised to the level of secretory granule. A two-sided double-labelling method was used to cross-react two hormones at a time with respect to their corresponding antibodies. All possible combinations of the six pituitary hormones were tested. Plurihormonal granules were found that contained LH + FSH, LH + TSH, and FSH + TSH. Each hormone was also found in monohormonal granules. Granule diameter was significantly larger in the pluri as opposed to monohormonal granules.     

Plurihormonality in the secretory granules of the normal human pituitary. An immunoelectron microscopic study

Summary Normal human autopsy anterior pituitary tissue from 5 cases was embedded in LR White resin and immunolabelled using silver-enhanced 5-nm protein A gold probes. Follicle stimulating hormone (FSH), thyroid stimulating hormone (TSH), luteinizing hormone (LH), adrenocorticotrophic hormone (ACTH), growth hormone (GH) and prolactin (PRL) were immunolocalised to the level of secretory granule.A two-sided double-labelling method was used to cross-react two hormones at a time with respect to their corresponding antibodies. All possible combinations of the six pituitary hormones were tested. Plurihormonal granules were found that contained LH+FSH, LH+TSH, and FSH+TSH. Each hormone was also found in monohormonal granules. Granule diameter was significantly larger in the pluri as opposed to monohormonal granules.