Increase in the hypothalamic tyrosine hydroxylase activity after lesion of the catecholaminergic neurons of the rat pontine tegmentum]

Hypothalamic tyrosine hydroxylase activity is increased 6 and 18 h after bilateral lesioning of the Locus Coerulues, in the Rat. An adrenocortical hypertrophy was observed previously, under the same experimental conditions. The neurochemical and neuroendocrinological implications of theses results are discussed.     

Variations in the hydrothermic contraction of the rat skin as a function of the age of the animals]

The tension developed in Rat skin by hydrothermal shrinkage is modified with ageing of the animals: the temperature of maximum tension decreases from birth to 1 month, then very slowly increases with age. At higher temperatures than that of maximum tension a relaxation occurs very rapidly in young Rats and in not yet senescent adult skins. These modifications appeared to be related to those of the nature of the intermolecular collagen cross-links with ageing.     

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.     

Selective representation of vibrissa at the level of cerebellar Purkinje cells by way of climbing fibers in rats]

In the Rat peripheral information from snout vibrissae are transmitted to cerebellar Purkinje cells of Crus I and II by both mossy and climbing fibers. The climbing fiber pathway is organized in a very precise manner, a particular Purkinje cell being preferentially activated by a single vibrissa.     

In vitro development of rat embryos obtained from diabetic mothers

Rat embryos of 9.5 or 10 days of gestation were removed from control or streptozotocin-diabetic mothers and cultured in normal rat serum (180 mg% glucose) or in diabetic serum (600 mg% glucose). The development of control embryos in normal serum was adequate. Embryos from normal mothers cultured in diabetic serum showed signs of developmental retardation. The development of embryos obtained from diabetic mothers was severely impaired, regardless of the gestational age or the culture medium. These results suggest that a diabetic maternal milieu produces irreversible effects in the embryo very early in gestation.     

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.     

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.     

Depression by morphine of various descending inhibitory controls modulating the transmission of nociceptive information at the spinal level in the rat

Recording from convergent neurones--i. e. those responding to both non-noxious and noxious cutaneous stimuli--in the dorsal horn of the intact anaesthetized Rat, two distinct effects are seen after application of noxious stimuli: there is an activation of units of the segmental pool, along with a very powerful inhibition of the remaining neuronal population (diffuse noxious inhibitory controls, DNIC). Morphine at doses inadequate to directly depress the activity of these units specifically blocks the inhibition. Since DNIC is dependent upon supraspinal mechanisms, these observations show that morphine is capable of depressing certain descending inhibitory controls, at least when these are induced by noxious peripheral stimuli.     

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.     

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.     

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.     

The influence of long term estrogen treatment on plasma prolactin levels induced by ether anesthesia in ovariectomized rats

Summary 2 methods of continuous estrogen delivery, polyestradiol phosphate injection and implantation of Silastic capsules of estradiol-17 , in ovariectomized rats induced increases in plasma prolactin in the afternoon (15.00–17.00) beginning at 1 week and continuing for 4–8 weeks. In addition these methods of estrogen treatment potentiated the ether-induced increase in plasma prolactin in the morning (9.00–11.00) beginning on week 2 and continuing for 3–8 weeks. These results indicate that estrogen activates the mechanisms that cause an afternoon surge in prolactin before potentiating a morning elevation induced by ether anesthesia.Acknowledgment. This work was supported by NIH General Research Support, grant No. RR05384-14 to Wayne State University School of Medicine. The authors also with to express their appreciation to Mrs C. Van De Walle for her expert technical assistance in the prolactin radioimmunoassay, to Dr Richard R. Gala for his advice and support of this project and to the Rat Pituitary Hormone Distribution Program of NIAMDD for the generous gift of Rat Prolactin.     

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.     

Degradation of collagen by the cariogenic bacteria, Streptococcus mutans

The behaviour of cariogenic Bacteria (Streptococcus mutans) is studied with regard to collagen, which represents 90% of the dentine organic matrix. Collagenase activity of cariogenic Bacteria is measured with radioactive precursors and gel electrophoresis and compared to reference bacterial collagenase (Clostridium histolyticum). Labelled collagen substrate has been prepared with two different methods: extraction by 0,5 M acetic acid from young Rat skin, previously labelled with L-proline 14C, or reduction by Na B3H4. Both collagen sutstrates have been incubated for 2 h in Terleckyj medium in which the Streptococcus mutans have been inoculated. The experiments show a proteolytic activity of Streptococcus Mutans on the collagen substrate.     

Monoamine oxidase activity of the hypothalamus and pituitary: alterations after pinealectomy, changes in photoperiod, or additions of melatonin in vitro.

Rat pituitary MAO activity was reduced by constant darkness and by additions of melatonin in vitro and was increased by constant light and by pinealectomy. Hypothalamic MAO activity followed the same pattern but was less dramatically affected. The data suggest that MAO may be a target enzyme for melatonin.     

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.     

Regional variations and particle binding of free amino acids in the rat brain: effects of amphetamine and methaqualone]

Amphetamine and methaqualone affected aspartate level in various regions of Rat brain. Increased aspartate level in cerebral cortex of methaqualone treated Rats was produced in the aspartate fraction whose binding to subcellular particules was Na+ dependant. This work suggest that aspartate level was altered only in brain fraction implicated in the pharmacological effects of the drugs.     

Role of calcium in the histamine release induced by D-galactosamine from rat mast cells

Rat peritoneal mast cells were isolated and purified by differential centrifugation in Ficoll. Cells pooled from three to four rats were suspended at approximately 10(6) cells/ml in a buffered salt solution and incubated for 1 h at 37 degrees C in 300 microliter volumes in the absence or presence (9 X 10(-4) M) of calcium chloride. Addition of D-galactosamine hydrochloride (DGM; 2.8 X 10(-4)M) caused (in addition to basal release) a mean +/- SEM percent histamine release of 15.7 +/- 5.2 in the presence of Ca++ and 19 +/- 4.9 in the absence of Ca++ (p greater than 0.05). It is suggested that D-galactosamine does not require extracellular Ca++ for the release of histamine from the rat mast cell.     

Effects of estradiol-7 alpha-butyric acid on hypothalamus cells]

When Rat uterus was incubated at 37 degrees with estradiol-7 alpha-butyric acid (OII-7 alpha-bu), no interference was observed with the intracellular estradiol receptors. In addition, OII-7 alpha-bu did not display estrogenic effect such as in vivo inhibition of LH secretion in Rat and in vitro increased activity of the enzyme ornithine-decarboxylase in the chick oviduct. Contrary to these negative findings, we have observed preoptic and septal cells in the guinea pig where micro-iontophoresis of OII-7 alpha-bu triggers changes of the electric activity within a second. We submit therefore, that this latter response is due to an interaction between the acid estrogen and the neuron membrane.