Biological effects of trilostane in vitro on oocyte maturation and fertilization in the hamster

The effects of the inhibition of steroidogenesis by trilostane on oocyte maturation were examined by studying spontaneous maturation and fertilization in vitro. 10(-6)M trilostane had no influence on the meiotic process, whether the oocytes were naked or not. At a concentration of 10(-6)M and 10(-7)M trilostane, low normal pronuclear formation and high polyspermy were found during in vitro fertilization. However, no retarded male pronuclear development could be detected in the trilostane-treated group. Thus, steroid producing activity within ova is apparently necessary to prevent multiple sperm penetration, but it has no effect on meiosis or the action of the so-called male pronucleus growth factor (MPGF).     

Phosphoramidon enhances allatostatin-mediated inhibition of juvenile hormone biosynthesis in the corpora allta of the cockroach,Diploptera punctata

Use of the enkephalinase inhibitor phosphoramidon in the in vitro radiochemical assay for juvenile hormone biosynthesis enhanced allatostatin-mediated inhibition of hormone production by corpora allata of the cockroach,Diploptera punctata. Significant increases in inhibition in day 2 virgin female CA by AST 1 (at 10^–7 M) and AST 4 (10^–8–10^–7 M) were observed in the presence of phosphoramidon (10^–5M or greater). No significant increases in inhibition were seen in CA from day 6 mated females with AST 4 (10^–9–10^–7M) and phosphoramidon combined. Phosphoramidon alone had no effect on JH biosynthesis. Analysis of allatostatin content of the CA, as determined by ELISA, revealed that addition of phosphoramidon to the medium increased the endogenous allatostatin conten in CA of virgin and mated females. The similarity in primary structure between allatostatins and enkephalin-like peptides and their similar distribution makes it probable that phosphoramidon acts by preventing breakdown of allatostatins within the CA.     

Postimplantation embryo culture for the assessment of the teratogenic potential and potency of compounds

Summary Whole rat embryos cultured during the early stages of organogenesis were subjected to a panel of selected chemicals. Of seventeen known in vivo teratogens, seventeen also induced specific malformations in embryos grown in culture. Of ten chemicals which were reported to be negative in in vivo rat teratogenicity studies, eight also did not provoke dysmorphogenic effects in vitro. Of five additionally tested retinoids, all induced multiple malformations. However, concentrations used to induce these effects varied considerably, isotretinoin inducing malformations at 10^–5M and arotinoid at 10^–11M. The results indicate qualitatively as well as quantitatively a high predictability of this in vitro system and suggest that the postimplantation embryo culture system may also be useful in the prospective testing of new drugs and environmental chemicals.     

Mechanical agitation of very dilute antiserum against IgE has no effect on basophil staining properties

A previously reported² effect of mechanically agitated dilutions of antiserum raised against IgE was investigated using the loss of metachromatic staining properties of human basophil leukocytes as a model. A series of 24 blind experiments was performed in which we determined the number of toluidine blue-stainable basophils after incubating with vortexed or non-vortexed dilutions of anti-IgE. Tenfold serial dilutions were used, in the range 10²¹ to 10³⁰ (6.6×10^–26 to 6.6×10^–35 M anti-IgE). We found no evidence for a different effect of strongly agitated dilutions, compared to dilutions made with minimal physical agitation. In fact, in our hands no effect of extreme dilutions was shown at all. We conclude that the effect of extreme dilutions of anti-IgE, reported by Davenas et al.², needs further clarification and that in this process the reproducibility of results between experimenters should be carefully determined.Acknowledgment. This study was partly funded by Homint.     

Inhibition and sex specific induction of spawning by serotonergic ligands in the zebra musselDreissena polymorpha (Pallas)

Serotonin (5-hydroxytryptamine, 5-HT) stimulates spawning in the zebra mussel (Dressena polymorpha), a macrofouling European bivalve that has recently invaded North America. To develop methods of controlling zebra mussel spawning, two vertebrate serotonin antagonists, methiothepin and metergoline, known to bind with high affinity to snail 5-HT receptors, were tested for their ability to block 5-HT-induced spawning in zebra mussels. Methiothepin inhibited 5-HT-induced spawning at concentrations as low as 10^–6 M. Metergoline (10^–4 M) inhibited 5-HT-induced spawning; however, at lower concentrations (10^–8 to 10^–5 M), metergoline by itself significantly induced spawning in male, but not female zebra mussels. Metergoline (10^–5 M)-induced male spawning was inhibited by 10^–5 M methiothepin. Thus, methiothepin is the most effective inhibitor and metergoline the most powerful inducer of spawning yet tested in zebra mussels.     

Wirkungsverstärkung von Adrenalin und Noradrenalin durch Azetylcholin am isolierten Irisdilatator des Kaninchens

Summary Radial strips of the isolated iris of rabbits were suspended in streaming Tyrode's solution and their contractions were registered isometrically. The contractions produced by adrenaline or noradrenaline were increased after the administration of eserine or neostigmine. Acetylcholine in a concentration 5.10^–7–5.10^–6 M enhanced the effect of adrenaline and noradrenaline on both, the normal and the chronically denervated dilator muscle. Acetylcholine did not enhance the contractions by adrenaline and noradrenaline in the presence of atropine. Choline in a concentration of 5.10^–6 M had no effect whereas concentrations of 5.10^–5 M were slightly effective.     

Fatty acid modulation of antiestrogen action and antiestrogen-binding protein in cultured lymphoid cells

Summary Nonsteroidal antiestrogens reversibly and specifically inhibited the proliferation of two estrogen receptornegative lymphoid cell lines (EL4 and Raji) in a dose-dependent manner. [³H]Thymidine incorporation of concanavalin A-stimulated primary splenocytes was also inhibited by 10^–6 M clomiphene (1-[4-(2-diethylaminoethoxy)phenyl]-1,2-diphenyl-2-chloroethylene). The antiproliferative effect could be prevented by the simultaneous presence in the growth medium of 10^–5 M linoleic acid or 10^–5 M arachidonic acid but not by 10^–6 M estradiol. Both lymphoid cell lines had high affinity antiestrogen-binding sites whose affinity could be altered by conditions of growth. Growth of EL4 cells in RPMI 1640 medium supplemented with charcoal-pretreated 5% fetal calf serum (charcoal-stripped medium) resulted in significantly higher affinity (K_d 0.54 nM±0.11 nM; n=6) than growth in medium supplemented with untreated serum (complete medium) (K_d=1.68 nM±0.48 nM; n=6) (p<0.001). This change in affinity was partly due to removal of fatty acids from the growth medium by charcoal pretreatment, since addition of 10^–5 M linoleic acid or 10^–5 M gamma-linolenic to charcoal-stripped medium decreased the affinity of the antiestrogen-binding protein. In contrast, growth in 10^–5 M stearic acid or 10^–5 M oleic acid did not significantly alter the affinity of the antiestrogen-binding protein, whereas 10^–5 M palmitic acid significantly increased its affinity. The same fatty acids were also tested for their intrinsic effects on EL4 cell proliferation. Oleic, linoleic and gamma-linolenic acids were growth stimulatory while stearic and palmitic acids were not. Thus linoleic and gamma-linolenic acids whose presence in the growth medium was associated with decreased affinity of [³H]tamoxifen (1-[4-(2-dimethylaminoethoxy)phenyl]-1,2-diphenylbut-1(Z)-ene) binding to the intracellular antiestrogen-binding protein were also growth stimulatory. Unsaturated fatty acids have previously been shown to inhibit binding of [³H]tamoxifen to the antiestrogen-binding protein in a cell-free system. The present observations demonstrate that unsaturated fatty acids also modify the affinity of the antiestrogen-binding protein in intact cells.     

VIP and histamine H2 receptor activity in human fetal gastric glands

Summary Vasoactive intestinal peptide (VIP, EC₅₀=6.4×10^–10 M) and histamine (EC₅₀=3×10^–6 M) activated the cyclic AMP generating system in gastric glands isolated from two human fetuses at 23 weeks gestation. Histamine antagonism by the H₂ receptor blockers cimetidine (Ki=0.35×10^–6 M) and ranitidine (ki=0.51×10^–7 M) clearly characterized the histaminic activation as being of the H₂ type. It is suggested that these two vasoactive hormones may operate as neurocrine/paracrine regulators of the differentiation and/or function of the human gastric mucosa in utero.     

Induction of the in vitro p-hydroxylation of14C-amphetamine stereoisomers in phenobarbital-treated rats

Summary The rate of p-hydroxylation of¹⁴C-(-)-amphetamine by liver microsomes was higher than that of (+)-isomer in phenobarbital-treated male rats. The apparent K_m values for (-)- and (+)-amphetamine hydroxylation were 4.54×10^–5 M and 2.27×10^–5 M respectively, in both treated and control animals.     

Effects of cycloheximide on protein synthesis in human lung tumors,regenerating rat liver and hepatomas

Summary 10^–4 M cycloheximide (CHM) inhibits leucine incorporation to about the same degree in slices of human lung tumors, rat hepatomas, regenerating livers and normal tissues. At 10^–6 M, CHM has a more pronounced effect on tumor tissue and regenerating liver than on normal tissues. 10^–8 M CHM stimulates protein synthesis in normal rat liver slices.     

Role of adenosine A1 and A2 receptors in the regulation of aldosterone production in rat adrenal glands

Summary To investigate the roles of adenosine A₁ and A₂ receptors in the regulation of aldosterone production, we examined the effects of adenosine and adenosine agonists (N⁶-cyclohexyl adenosine; selective adenosine A₁ receptor agonist and 5-N-ethylcarboxamine adenosine; selective adenosine A₂ receptor agonist) on aldosterone and cyclic AMP production in rat adrenal capsular cells. Neither adenosine nor 5-N-ethylcarboxamine adenosine caused significant effects on basal aldosterone or cyclic AMP production. Also, adenosine (10^–3M) showed no consistent effects on aldosterone and cyclic AMP production induced by ACTH. On the other hand, N⁶-cyclohexyl adenosine exhibited a significant inhibition of basal aldosterone and cyclic AMP production at doses of 10^–4 M and 10^–3 M; furthermore, 10^–3 M N⁶-cyclohexyl adenosine inhibited aldosterone and cyclic AMP production stimulated by ACTH. These results suggest that adenosine A₁ receptors are coupled to and inhibit adenylate cyclase and may be involved in the inhibition of aldosterone production.     

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.     

Somatostatin inhibits in vitro release of luteinizing hormone releasing hormone from rat mediobasal hypothalamic slices

Summary Somatostatin, in concentrations ranging from 10^–10 M to 10^–7 M, induces a dose-dependent inhibition of LHRH release from mediobasal hypothalamic slices incubated in vitro. In contrast, VIP, secretin, glucagon, substance P, neurotensin and arginine-vasotocin do not affect spontaneous release of LHRH.     

Effects of ouabain and furosemide on saliva secretion induced by sympathomimetic agents in isolated,perfused rat submandibular glands

Summary The presence of 10^–3 M ouabain or furosemide in the perfusate inhibited saliva secretion induced by either isoproterenol (10^–5 M) or phenylephrine (10^–5 M) from isolated rat submandibular glands and caused characteristic alterations in the electrolyte composition of saliva.     

Activation by S-adenosylhomocysteine of norepinephrine and serotonin in vitro uptake in synaptosomal preparations from rat brain

Summary S-Adenosylhomocysteine (10^–7–10^–5 M) activated norepinephrine (NE) and serotonin (5HT) in vitro uptake in synaptosomal preparations from rat brain, but did not affect dopamine (DA) uptake. When administered to rats (7 mg/kg i.p.), it had the same effect on in vitro NE and 5HT uptake. It did not affect NE and 5HT release.Work achieved within the frame of the research contract institut Mérieux., Institut National des Sciences Appliquées.     

Action,in vitro et in vivo,de l'angiotensine II sur le captage cardiaque de la noradrénaline

Summary The action of angiotensin II on cardiac uptake of norepinephrine was investigated in the rat in vivo and in vitro. In contrast to desipramine, neither infusion of subpressive (10 ng/kg/min) or pressive (50–150 ng/kg/min) amounts of angiotensin on intact and/or binephrectomized rats, nor incubation of cardiac slices with angiotensin II (10^–5; 10^–9 M) impair the accumulation of tritiated norepinephrine and the level of metabolites. It is thus concluded that there is no inhibiting action of angiotensin II on the cardiac uptake of norepinephrine.     

Calcium and the contractile response to prostaglandin in the smooth muscle of guinea-pig stomach

Summary In the longitudinal smooth muscle of guinea-pig stomach, verapamil (10^–5 M) which showed marked suppression of high K-induced contractures, did not suppress the contractile response to PGE₁ (1.5×10^–9 to 10^–6 M) markedly. These results suggest that the contractile mechanism of PGE₁ in guinea-pig stomach may mainly depend on a release of bound Ca in the cell and partly depend on a Ca influx from the extracellular origin.     

Naringenin inhibition on expiants in vitro ofCichorium intybus (Chicory)

Riassunto La naringenina alla concentrazione di 10^–4 M inibisce in modo totale l'emissione di gemme in radici diCichorium intybus in vitro senza tuttavia bloccare completamente la callogenesi. A concentrazioni scalari minori (10^–5, 10^–6, 10^–7 M) questa sostanza causa una inibizione solo nella fase iniziale dell'esperienza.     

Modification of theophylline-induced lipolysis in human fat cells after trypsination

Summary Trypsin-treatment of human fat cells results in the potentiation of the lipolytic response and the cAMP accumulation induced by theophylline (5·10^–4 M) but not of those induced by theophylline (5·10^–3 M). The amount of cAMP formed after exposure to theophylline (5·10^–3 M) plus norepinephrine (5·10^–6 M) remains, however, 2.6fold higher in trypsin-treated human fat cells than in the control ones.Acknowledgments. The authors gratefully acknowledge the help of the surgical staff of the C. H. I. of Poissy. This work was supported by grants from the C. H. I. of Poissy and from the Université René Descartes.     

Catecholamines in bovine semen

Summary In seminal plasma 5×10^–6 M noradrenaline was found to induced head-to-head association in bull spermatozoa. The sum of noradrenaline and adrenaline in freshly collected semen was 10 ng/ml (5.2×10^–8M), i.e., about 100 times lower than previously reported.