Dexamethasone suppression of ovulation in PMS-treated immature rats.

A single injection of 2.0 mg/kg dexamethasone (DXM) administered at 51 h after pregnant mare serum gonadatropin (PMS) treatment inhibited both ovulation and luteinization. S.c. injection of human chorionic gonadotropin (HGG) caused ovulation and luteinization in DXM-PMS-treated rats, whereas treatment with ACTH failed to overcome the DXM inhibitory effect. These findings are interpreted to indicate that DXM inhibits ovulation through a mechanism which might involve the central nervous system.     

Dexamethasone protection against the acute lethality of ethanol in mice

Summary The administration of dexamethasone (DXM, 2.00 mg/kg) 1 h prior to the injection of lethal doses of ethanol was found to offer complete protection against ethanol toxicity at doses up to 5.25 g/kg and partial protection using higher doses. It is suggested that DXM central action might be involved in the protection against ethanol toxicity.Supported by a grant from U.S. National Aeronautics and Space Administration.     

Dexamethasone-induced neutrophilia. Negative correlation with increased plasma adrenaline concentrations

Maximal increments in adrenaline and dexamethasone (DXM) plasma concentrations were observed c15 (T50 40 min) and 30 (T50 210-240 min) minutes after an i.v. DXM dose (6 mg/m2 BSA) in man. There appears, however, to be no direct interaction between these agents in the development of induced neutrophilia, which occurs c240 min postinjection.     

Teratogenicity screening in standardized chick embryo culture: effects of dexamethasone and diphenylhydantoin

Teratogenic and toxic effects of DXM and DPH were tested using a standardized chick embryo culture. Survival, growth and malformations were scored with respect to the drug concentrations used. DXM (greater than 10(-8) mol/l) inhibited the differentiation of the extraembryonic blood circulation and induced craniofacial anomalies. DPH (greater than 1.5 10(-5) mol/l) induced cardiomegaly, craniofacial and somitic anomalies. Both drugs were lethal at 10(-3) mol/l. Comparison of results obtained with 8 drugs shows that the method has a good discriminative power and specificity and that it can be used as a simple, reliable and economical primary screening test, making it possible to reduce the use of animals in toxicological studies.     

Dexamethasone-induced neutrophilia. Negative correlation with increased plasma adrenaline concentrations

Summary Maximal increments in adrenaline and dexamethasone (DXM) plasma concentrations were observed c15 (T₅₀ 40 min) and 30 (T₅₀ 210–240 min) minutes after an i.v. DXM dose (6 mg/m² BSA) in man. There appears, however, to be no direct interaction between these agents in the development of induced neutrophilia, which occurs c240 min postinjection.Acknowledgments. The authors wish to thank Mrs C. Ditzler, Merck Sharp & Dohme Research Laboratories, USA, for determining the plasma dexamethasone concentrations J. M. M. is currently on sabbatical leave from McGaw Laboratories, USA. C. R. B. is a Rhodes scholar.     

Cyclic AMP is a likely mediator of ovulation in the tsetse fly.

Ovulation in tsetse flies is normally induced by mating, but virgins can be stimulated to ovulate with an injection of dibutyryl cyclic AMP, cholera toxin (a cyclic AMP generator), or aminophylline (a phosphodiesterase inhibitor). Thus, elevation of cyclic AMP is a likely link in the events leading to ovulation.     

The involvement of serotonin in induced ovulation in the immature rat.

In pregnant mare's serum gonadotropin (PMS) treated immature rats the cortex, cerebellum, caudate nucleus and hypothalamus were isolated and analyzed for their serotonin (5-HT) content at 6-h intervals for 72 h. Results showed a general trend of significant variation occurring in days 1 and 3 after PMS injection with no major variations observed on the second day. The results obtained suggest a possible involvement of 5-HT in the control of ovulation.     

The involvement of serotonin in induced ovulation in the immature rat

Summary In pregnant mare's serum gonadotropin (PMS) treated immature rats the cortex, cerebellum, caudate nucleus and hypothalamus were isolated and analyzed for their serotonin (5-HT) content at 6-h intervals for 72 h. Results showed a general trend of significant variation occurring in days 1 and 3 after PMS injection with no major variations observed on the second day. The results obtained suggest a possible involvement of 5-HT in the control of ovulation.     

Teratogenicity screening in standardized chick embryo culture: Effects of dexamethasone and diphenylhydantoin

Summary Teratogenic and toxic effects of DXM and DPH were tested using a standardized chick embryo culture. Survival, growth and malformations were scored with respect to the drug concentrations used. DXM (>10^–8 mol/l) inhibited the differentiation of the extraembryonic blood circulation and induced craniofacial anomalies. DPH (>1.5 10^–5 mol/l) induced cardiomegaly, craniofacial and somitic anomalies. Both drugs were lethal at 10^–3 mol/l. Comparison of results obtained with 8 drugs shows that the method has a good discriminative power and specificity and that it can be used as a simple, reliable and economical primary screening test, making it possible to reduce the use of animals in toxicological studies.Supported by the grant 4.790.0.84.17 from the Swiss National Science Foundation.     

Cyclic AMP is a likely mediator of ovulation in the tsetse fly

Summary Ovulation in tsetse flies is normally induced by mating, but virgins can be stimulated to ovulate with an injection of dibutyryl cyclic AMP, cholera toxin (a cyclic AMP generator), or aminophylline (a phosphodiesterase inhibitor). Thus, elevation of cyclic AMP is a likely link in the events leading to ovulation.We thank J. de Wilde and W.A. Foster for helpful comments. D.L.D.'s research visit to ICIPE was supported by a grant from the Mid-West Universities Consortium for International Activities.     

Modifications of ovarian follicle reactivity to LH in rats treated with FSH at the beginning of the estrous cycle]

LH perfusion was performed on proestrus under pentobarbital anaesthesia in 4-days cyclic female Rats treated or not treated with FSH at the onset of estrous cycle. The number of follicles capable of undergoing luteinization was shown to be dependent upon the amount of LH available.     

Extranuclear3H-thymidine incorporation in subcortical cytoplasmic organelles of primary oocytes in the Japanese quail (Coturnix coturnix japonica)

Résumé Après une injection intrapéritonéale de thymidine³H à la caille japonaise pondeuse, nous avons trouvé une incorporation de ce précurseur dans des organites cytoplasmiques subcorticaux des oocytes, quelques jours avant leur ovulation.     

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.     

Epilepsy in women. Oestrogen and progesterone plasma levels

Summary Comparison is made between numbers of fits and estrogen, progesterone plasma values during the menstrual cycle of women with epilepsy. All six cycles in women with ovulation had a significant positive correlation between estrogen/progesterone ratio and scores of fits. Three periods without ovulation all showed a significant correlation to estrogen variations.Acknowledgments. This work was supported by Gunvor och Josef Anérs stiftelse, Med. fac. University of Umeå, The Swedish Medical Research Council (Proj. No. 2148) and Karl Oskar Hansson's fund.     

Effect of acute administration of delta 1-tetrahydrocannabinol on beta-endorphin levels in plasma and brain tissue of the rat

Acute treatment with delta 1-tetrahydrocannabinol (delta 1-THC) elevated the concentration of beta-endorphin-like immunoreactivity (beta-ELIR) in plasma and in the hypothalamus, but not in the hippocampus of rats habituated to the injection procedure. These effects were not obtained with the psychotropically inert analog of delta 1-THC, cannabidiol. In animals that had not been habituated to the injection procedure, placebo treatment induced a decrease in hippocampal beta-ELIR.     

Strukturelle und funktionelle Veränderungen am menschlichen Ovar unter Einwirkung hormonaler Antikonzeptiva

Summary In two cases, a fresh corpus luteum was found during treatment with hormonal anticonceptiva (Lyndiol 2.5^®). The decreased excretion of all oestrogen fractions can be explained by the lack of proliferation of the theca interna. The striking proliferation of the follicle epithelium after the completed ovulation is as yet an unexplained phenomenon. The possible endocrine actions of such steroid combinations upon the pituitary are discussed. Further investigations are in progress.     

Synthesis of ovulation-inhibiting compounds; structure-activity relationship.

We describe the synthesis of some new derivatives of benzo(4, 5)cyclohepta(1, 2-b)thiophene which inhibit ovulation and the secretion of luteinizing hormone (LH) in the rat. We also describe the relationship between the structure and activity of these compounds.     

Synthesis of ovulation-inhibiting compounds; Structure-activity relationship

Summary We describe the synthesis of some new derivatives of benzo (4,5) cyclohepta (1,2-b) thiophene which inhibit ovulation and the secretion of luteinizing hormone (LH) in the rat. We also describe the relationship between the structure and activity of these compounds.     

Inhibition of ovulation in rats by antagonists to serotonin and by a new tricyclic compound.

The ovulation inhibiting activity in adult rats of the 5HT-antagonists cyproheptadine, mianserin and methysergide is shown. Furthermore the activity of a newly synthetized Cycloheptathiophenederivative, compound 26-921, which inhibits LH-secretion and consequently ovulation, is described.     

Epilepsy in women. Oestrogen and progesterone plasma levels.

Comparison is made between numbers of fits and estrogen, progesterone plasma values during the menstrual cycle of women with epilepsy. All six cycles in women with ovulation had a significant positive correlation between estrogen/progesterone ratio and scores of fits. Three periods without ovulation all showed a significant correlation to estrogen variations.