Browsing by Author "LARA, H"

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    BIOCHEMICAL-EVIDENCE FOR THE PRESENCE OF SMALL AND LARGE NORADRENERGIC STORAGE-VESICLES ISOLATED FROM CAT OVARY IN ISOOSMOTIC CONDITIONS - DISTRIBUTION OF DOPAMINE-BETA-HYDROXYLASE ACTIVITY
    (1989) LARA, H; BELMAR, J
    The cat ovary presents unusually high levels of noradrenaline that change according to the endocrine status of the animal. Their functional meaning remains unknown. The cat ovary innervation, unlike that of other organs receiving noradrenergic innervation, has been poorly characterized on biochemical grounds. We present here a biochemical characterization of the neurotransmitter storage. By using hyperosmotic and isoosmotic gradients evidence is presented that noradrenaline is associated to two different populations of vesicles. In hyperosmomolarity conditions (sucrose gradients) "light" vesicles (density 1.12 g/ml) and "heavy" vesicles (density 1.17 g/ml) appeared. In both vesicles, noradrenaline and dopamine-.beta.-hydroxylase were found. In isoosmotic Percoll gradients distribution of the markers also suggested the presence of two vesicle populations. Light vesicles (density 1.033 g/ml) with high dopamine-.beta.-hydroxylase activity but very low levels of noradrenaline and adenosine triphosphate; [3H]noradrenaline, used as a specific exogenous vesicle marker, was feebly incorporated in this fraction. Heavy vesicles (density 1.041 g/ml) containing high levels of noradrenaline, adenosine triphosphate, low levels of dopamine-.beta.-hydroxylase activity are able to incorporate high amounts of [3H]noradrenaline. In these gradients, Mg2+ activated ATPase activity was present in both vesicle fractions. Sedimentation analysis by analytical differential centrifugation also disclosed two types of vesicles; large vesicles with a sedimentation coefficient between 348 and 308 .hivin.S and small vesicles with a sedimentation coefficient of 96 .hivin.S. Large vesicles were associated with noradrenaline-.beta.-hydroxylase activity, while small vesicles were associated only with noradrenaline. In isoosmotic conditions the use of other microsomal markers allowed us to define the degree of contamination of the vesicle fractions. It was found that the noradrenergic heavy vesicles fraction presented under 11% of 5-nucleotidase activity of the total activity present in the gradient and less than 5% of acid phosphatase, NADH-cytochrome c reductase and monoaminooxidase of the total activities in the gradients. In isoomotic conditions the physical properties of presumed vesicles were apparently undisturbed supporting the current morphometric observations. Our results then suggest prevailing roles for each type of vesicle: synthesis for light vesicles, and storage and/or release for heavy ones.
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    CHANGES IN APYRASE ACTIVITY IN UTERUS AND MAMMARY-GLAND DURING THE LACTOGENIC CYCLE
    (1992) VALENZUELA, MA; COLLADOS, L; KETTLUN, AM; MANCILLA, M; LARA, H; PUENTE, J; ARANDA, E; CHAYET, L; ALVAREZ, LCA; TRAVERSOCORI, A
    1. The purpose of this present research was to explore the possible roles of ATP-diphosphohydrolase (apyrase) in two tissues with high energetic demands during cell proliferation and differentiation.
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    CHANGES IN NORADRENERGIC VESICLE MARKERS OF RABBIT OVIDUCTS DURING PROGESTERONE TREATMENT
    (1983) BELMAR, J; LARA, H; GALLEGUILLOS, X
    The effect of progesterone (P) on norepinephrine (NE), [3H]norepinephrine ([3H]NE) and dopamine .beta.-hydroxylase (DBH) in noradrenergic vesicles from rabbit oviducts was studied after daily injections of the hormone during different periods (4, 7 and 15 days). Progesterone induced a concomitant increase in NE and DBH activity and [3H]NE uptake. To study the mechanism involved in such effects, 4 tissue fractions were obtained by differential centrifugation of the oviducts of which the vesicular fraction was applied over continuous sucrose gradients (0.3-2 M). The changes induced by P in markers of tissue and gradient fractions showed an increase of the NE storage capacity which could be ascribed to an increase in the number of storage vesicles, and/or to a higher extravesicular storage capacity. The occurrence of these mechanisms during pregnancy or after P treatment could account for the (long-lasting) high levels of NE observed in such instances.
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    CHANGES OF NOREPINEPHRINE LEVELS, TYROSINE-HYDROXYLASE AND DOPAMINE-BETA-HYDROXYLASE ACTIVITIES AFTER CASTRATION AND TESTOSTERONE TREATMENT IN VAS-DEFERENS OF ADULT-RATS
    (1989) BUSTAMANTE, D; LARA, H; BELMAR, J
    Norepinephrine levels and tyrosine hydroxylase and dopamine-.beta.-hydroxylase activities have been used to evaluate the effect of castration and testosterone treatment on the sympathetic innervation of the adult was deferens. Castration was followed by a decrease in both norepinephrine content and tyrosine hydroxylase activity, even though the changes were not concomitant. Treatment of castrated animals with testosterone reversed the effect of castration on organ weight and norepinephrine content, but only a short-lasting increase in tyrosine hydroxylase activity occurred at the beginning of testosterone treatments. In contrast, the testosterone-induced recovery of norepinephrine content observed at this time was accompanied by a marked increase in dopamine-.beta.-hydroxylase activity. The results suggest that in rat was deferens, norepinephrine levels are under androgenic control and that this regulation mainly involves changes in dopamine-.beta.-hydroxylase activity rather than a modulation of tyrosine hydroxylase.
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    EFFECT OF CASTRATION AND TESTOSTERONE ON NOREPINEPHRINE STORAGE AND ON THE RELEASE OF [H-3]NOREPINEPHRINE FROM RAT VAS-DEFERENS
    (1985) LARA, H; GALLEGUILLOS, X; ARRAU, J; BELMAR, J
    Norepinephrine and dopamine-.beta.-hydroxylase, used as noradrenergic vesicle markers, were decreased in the rat vas deferens 10 days after castration. Five days of testosterone administration to castrated animals increased the enzyme activity over that of controls but did not modify norepinephrine content. In tissue fractions obtained by differential centrifugation, the highest activities of the noradrenergic markers appeared in the vesicular fraction of controls and in the soluble fraction of castrated animals. Testosterone reversed the effect of castration: it increased dopamine-.beta.-hydroxylase activity in the vesicular and soluble fractions, while norepinephrine increased only in the vesicular fraction. Results obtained after continuous sucrose gradient centrifugation of vesicular fractions suggested that these changes principally affected the number of light noradrenergic vesicles while testosterone increased the number of vesicles reduced by castration. Hormonal manipulations also modified some functional properties of nerve endings: norepinephrine depletion after transmural stimulation in the presence of tetraethylammonium, as well as the release of the neurotransmitter, were decreased after castration. These effects were reversed by testosterone. A modulatory effect of testosterone on the norepinephrine storage system and on the functional properties of the adrenergic innervation of vas deferns is suggested.
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    RELEASE OF H-3 NORADRENALINE FROM THE RAT OVIDUCT - CHANGES DURING ESTROUS-CYCLE AND BY PROGESTERONE INVITRO
    (1990) CHIAPPE, P; GALLEGUILLOS, X; LARA, H; FUENTEALBA, B; FORRAY, I; BELMAR, J
    Rat oviduct noradrenergic innervation seems to be under the influence of hormonal modulation. Noradrenaline level is specifically affected, but other processes like the release of the neurotransmitter have not yet been studied. In this work the release of 3H-noradrenaline (3H-NA) during the estrous cycle and its modification by progesterone "in vitro", were studied. The basal 3H-NA outflow was unchanged during the estrous cycle. However, the induced release (K+, 80 mM) was maximal during estrous. After progesterone, induced 3H-NA release was inhibited at low concentrations (5 .mu.M); under higher concentrations (50 .mu.M) the effect persisted but basal outflow of radioactivity was increased. The inhibitory effect was potentiated by RU-486 (Progesterone blocker). Results suggest a modulatory role for the hormone and it could be related to interactions with nerve-ending membranes and not with classical nuclear receptors.