Increases in frequency of sister chromatid exchange following tumor grafts in different immunocompetent hosts]

Measurement of sister chromatid exchanges (SCEs) frequency of inbred Rat or nu/nu Mice bone marrow cells, following tumour grafts, have been developed. Increase of SCEs was observed in hosts which present or not metases and with reduced survival rates after malignant tumour grafts. These results suggest a remote control of tumoral tissue by a diffused matter effect.     

Pharmacological study of para-aminoclonidine, an alpha sympathomimetic]

Para-aminoclonidine is a more potent alpha-adrenergic agent than clonidine; in vitro on Rat aorta it is 150 times more active than NE, in vivo on pithed Rat it is still twice as active. The hypotensive action of paraaminoclondine is only manifested when given intraventricularly. In the conscious Rat, it has a diuretic action when given per os. Following IV injection in the anaesthetized Dog, the para-aminoclonidine induces an essentially hydric diuresis which is independet of its hypertensive action.     

Inhibition of post-hemicastration hypertrophy of the remaining testis by testosterone or aqueous testicular extract treatments in the young rat]

In the 10 day old hemicastrated Rat daily injections of testosterone (total doses of 0.04 to 4 mg/Rat) or of proteinaceous extract of Rat testis (4 mg/Rat) inhibit compensatory hypertrophy of the remaining testis. Both testosterone and testicular proteinaceous extract could be involved in the growing processes of the testis, locally or by means of modification of gonadotropin secretion. Results have been analysed by covariance analysis to eliminate the influence of body weight variations.     

Comparison in genetically obese and normal rats of the uptake and incorporation of labelled lauric acid, oleic acid, and glycerol by the isolated perfused liver]

Lauric acid, labelled oleic acid and glycerol are perfused in isolated liver of fafa Rats and Wistar Rats previously subjected to fasting. They synthesize TG and PL de novo, though in long time experiments with the normal Rat, the most important method of synthesis is an exchange of AG of the endogenous glycerolipids. However PL are not synthesized with lauric acid. In the livers of fafa Rats the synthesis of TG with oleic acid and glycerol is higher than in livers of Wistar Rats: 16:0 18 : 1 18: 1, 16:0 18: 1 18: 2, 18 : 1 18 :1 18:1, 16 : 0 16 :0 18 : 1 (this TG is not present in liver of Wistar Rat). The hepatic synthesis of PL by the fafa Rat, is less important after 15 min while it is important with Wistar Rats. The synthesized TG with lauric acid (only the TG 12 : 0 12 : 0 12 : 0 with the fafa Rat) are more rapidly oxidized by liver of obese Rat than by liver of normal Rat.     

Effects of mescaline and lysergide on the mechanical responses of isolated organs of the rat to catecholamines and the role of calcium transfers in these phenomena]

On isolated Rat vas deferens the contracting responses of noradrenaline and dopamine are increased by mescaline (23 micromoles) and decreased by lysergide (15 micromoles). Similarly, on isolated Rat duodenum previously decalcified the hypertonic responses of recalcification are modified in the opposite direction by the two agonists. On the other hand, mescaline such as lysergide increase the fall of tonus which ensues the decalcification of isolated duodenum.     

Vitamin A consumption in pregnant and non pregnant rats, and in castrated rats receiving or not receiving estradiol or pregnenolone; relation to tocopherol and cytochrome P-450]

Consumption of vitamin A and cytochrome P 450 by pregnant Rat is more important than in non pregnant and ovariectomised Rat. Estradiol implant in ovariectomised female has some, but slighter, influence only on retinol. These physiological situations have no action on the hepatic levels of tocopherols (total and alpha). These results are discussed.     

Immunohistochemical localization of carbonic anhydrase C in the rat central nervous system]

With obtention of specific antibodies against isoenzyme C of Rat carbonic anhydrase it was possible to realize an immunohistochemical localisation in central nervous system of Rat. Results showed that this enzyme was mainly localized in cytoplasm of oligodendroglial cells and in low concentration in myelin sheath.     

Proliferation of adipose cells and their lipid accumulation in the rat at the perinatal stage; histoautoradiographic study]

After thymidine-3H injection into pregnant Rat, histoautoradiographic studies showed that adipose cell proliferation in different subcutaneous and visceral sites, was very important in Rat foetuses about 24 h before birth and that lipid accumulation in the labelled cells was very fast during perinatal 48 h.     

Reduction of isoprenaline induced tachycardia in pregnant rats. Role of a serum factor]

The in vivo isoprenaline (50 microgram/kg) induced tachycardia (beta 1 adrenergic stimulant effect) was decreased in pregnant (20th day) Rats compared to non pregnant Rats. The in vitro positive chronotropic effect of isoprenaline (10 ng/ml) on cultured Rat heart cells was abolished by pregnant Rat serum whereas progesterone (0.10 to 5 microgram/ml) or oestradiol (0.1 to 25 microgram/ml) were ineffective. The decreased beta 1 adrenergic responsiveness in pregnant Rats could be related to a seric factor, different from these two hormones.     

Increase in spontaneous beating frequency in rat heart cells cultured in homologous serum]

Rat serum at different concentrations added to cultured Rat heart cells medium increased spontaneous beating frequency of myoblasts. This increase occurred instantaneously and lasted more than 24 hrs. It was related to the serum concentration used. Electrophysiological recording showed a decrease in the iso-electric phase duration of membrane potential, with no change in action potential. In spite of the beating frequency increase, cells remained sensitive to the chronotrope positive action induced by Isoprenaline. There was no difference between male and female sera. The global results could partly be explained by the action of Ca++ in Rat serum.     

Variations of testosterone uptake by gonadotropic cells of the adenohypophysis of the rat

Testosterone (T) could be detected by immunocytochemistry after cryoultramicrotomy and T is likely bound on a binding site of a high affinity. Castration and adrenalectomy involve a swift disappearance of T in the gonadotropic cells. Synthesis of new binding sites was induced by daily T injection in the castrated and surrenalectomized Rat from 90 days. This synthesis is inhibited by cycloheximide. These data suggest that binding sites are proteins. The captation of T by the gonadotropic cells was diminished similarly at the diminution of T, afterwards, T captation was stabilized at a weak level which became stable for several weeks. It seems that immunocytochemistry permits the study of the variation of T captation by Rat pituitary gonadotropic cells.     

Permissivity of the rat (Rattus rattus) of Guadeloupe with regard to Schistosoma mansoni and evidence for migration of adult schistosomes to the lungs]

In contrast to the laboratory Rat, the Rat (Rattus rattus) of Guadeloupe is a favorable host for the life cycle of S. mansoni: the parasite population is maintained at a high level (between 8 and 16% in this host until the 16th week and reproduces normally). The evolution of the parasitose is marked, shortly after the 8th week, by a transfer of schistosomes from the liver to the lungs.     

Plasma growth hormone in the rabbit fetus. Relation to maturation of the liver and lung]

Day 25 after insemination is a date of peculiar importance in the maturation of several organs in the Rabbit fetus. From day 25 onward the fetal liver stores increasing amounts of glycogen and the lung stores increasing amounts of lecithins, concomitant with sudden rise in the activity of lung phosphatidic-acid phosphohydrolase. Earlier studies on decapitated fetuses established that glycogen storage in the liver is dependent on a dual hormonal control, comprising a pituitary hormone like growth hormone or prolactin (some placental hormones share the same activity) and corticosteroids (Jost, 1961). Since the variations in endogenous corticosteroids do not seem to herald these liver or lung changes (Mulay et al., 1973), a study was made of growth hormone. Plasma immunoreactive growth hormone--determined with a heterologous Rat system (Kervran et al., 1976)--increases eightfold between days 23 and 25. During the same time plasma prolactin does not change according to McNeily and Friesen, 1978, and to unpublished data obtained with Dr McNeilly. In preliminary assays, Rat growth hormone was seen to increase phosphorylase "a" activity in the lung of 18.5 day-old Rat fetuses, thus anticipating normal development. We suggest that growth hormone plays a role in initiating liver and lung maturation.     

Evidence of an ileal hormone inhibiting pancreatic secretion (ACP anticholecystokinine peptide)]

The contact of long and medium chain fatty acids with the ileal mucosa inhibits basal or stimulated pancreatic protein secretion of Man, Dog, Cat and Rat. This inhibition is due to an inhibitory factor transmitted by cross-circulation. We isolated from partially purified extracts of Pig ileum a peptide which inhibits strongly volume and protein pancreatic output of the conscious Rat. We propose to call this factor ACP, anticholecystokinine peptide.     

Dissolution of the pulmonary collagen of the normal rat by repeated pepsin action]

A non-denaturating method of extracting collagen from Rat lungs was developed. It consists in dissolving the collagen by repeated action of pepsin. Depending on the age of the animal, efficiency values between 50 and 90% are obtained.     

Histofluorescence of catecholamines and visualization of retrograde transported peroxidase in the same tissue section and in the same neuron]

The demonstration of fluorescent catecholamines and horseradish peroxidase (HRP) in the same neuron has been achieved in the Rat in two ways: by submitting vibratome sections to a modified glyoxylic acid fluorescence method followed by the usual procedure to reveal HRP; or by combining the last procedure with the cryostat technique of Chiba et coll. After HRP injection into the striatum or the nucleus accumbens of the Rat, non-fluorescent HRP labelled neurons were observed in the substantia nigra and the ventral tegmental area respectively, in addition to the HRP labelled fluorescent dopaminergic neurons.     

Comparison in genetically obese and normal rats in the secretion of lipids synthesized from labeled lauric and oleic acids and glycerol in isolated perfused liver]

(1) Isolated livers of previously fasted fafa and Wistar Rats are perfused with labelled oleic acid and glycerol. Two pools of synthesized lipids are studied: --a pool of liver lipids: labelled TG 16:0, 16:0, 18:1, 16:0, 18:1, 18:1 and 18:1, 18:1, 18:1 are synthesized more by the fafa than by the Wistar Rat liver, The TG 16:0, 18:1, 18:2 appears in the liver of the 2 rat strains. After a 30 min. perfusion, the PL are synthesized less by the fafa than by Wistar Rat liver; --a pool of lipids released in the circulation. The labelled tG 16:0, 18:1, 18:2, are increased in the perfusate of fafa rat. The labelled TG 18:1, 18:1, 18:2 and 18:1, 18:2, 18:2 are in the same amount. (2) The liver synthesis of TG 12:0, 12:0, 12:0 is demonstrated in the fafa Rat by a lauric acid perfusion. This TG is not present in circulation, when a Wistar Rat liver synthesizes and releases with this TG, TG containing 1 or 2 molecules of lauric acid.     

Effect of alpha-tocopherol (vitamin E) on the utilization of vitamin A and induction of cytochrome P 450 in rats receiving DDT]

During detoxication processes of DDT, there is, in the Rat, interference between vitamins A and E (D.1.alpha-tocopherol acetate). Vitamin E spares retinal and has a slighter but significant influence on P 450 cytochrome induction. These results are discussed.     

Modulation of 3-hydroxy-3-methyl glutaryl CoA reductase by 2,3-diphosphoglyceric acid

Rat liver microsomal 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase was activated by 50% at a concentration of 0.4 mM 2,3-diphosphoglyceric acid (DPG) and by 11-fold at 10 mM DPG. DPG also prevented the inactivation of HMG-CoA reductase by ATP and Mg++. Rat liver microsomal HMG-CoA reductase prepared in the presence of 1 mM DPG was significantly more active than when prepared in the absence of DPG. Activation of the enzyme by DPG and protection of the enzyme against inhibition by ATP and Mg++ by DPG were also observed with solubilized HMG-CoA reductase.     

Inhibition of the preovulatory secretion of gonadotropins by prolactin in rats seems to depend on the strain used

Intraperitoneal injection of Rat Prolactin to cyclic female Rats results in preovulatory changes which depend on the strain of animals. Specifically, preovulatory surges of luteinizing hormone and follicle stimulating hormone were suppressed in Sprague-Dawley Rats while delayed but enhanced preovulatory surges of both gonadotropins were observed in Wistar strain.