Browsing by Author "Cuellar, C"

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    Allopregnanolone-induced modification of presynaptic basal and K+-induced [3H]-norepinephrine efflux from rat cortical slices during the estrous cycle
    (1998) Belmar, J; Cuellar, C; Llona, I; Arancibia, S; Kusch, C; Tapia-Arancibia, L; Pinter, A; Perez, H
    Superfused frontal slices of cerebral cortex were preloaded with [H-3]-norepinephrine ([H-3]NE). Basal [H-3]NE efflux and Kf-induced [H-3]NE release were studied during the estrous cycle and in the presence of neurosteroids. Basal [H-3]NE efflux showed estrous cycle-related variations, with lowest values found during estrus and diestrus II. Allopregnanolone (10(-9) M) potentiated basal [H-3]NE efflux from the Ist minute of its application; the effect of the steroid was still present after 20 min. This effect was also dependent upon the estrous cycle, since basal [H-3]NE efflux was mainly increased during estrus diestrus I, and to a lesser degree only during proestrus. During diestrus II and after ovariectomy, basal [H-3]NE efflux was no longer affected by the neurosteroid. In the presence of yohimbine (10(-6) M), the effect of allopregnanolone on basal efflux was potentiated only during the first 3 min but vanished thereafter. Allopregnanolone (10(-9) M) potentiated the K+-induced [H-3]NE release during estrus, but pregnenolone (10(-9) M) was ineffective, suggesting specificity of the neurosteroid. Yohimbine (10(-6) M) also potentiated K+-induced [H-3]NE release. When applied simultaneously with allopregnanolone (10(-9) M), a potentiating effect on [H-3]NE release was observed. The present results suggest that allopregnanolone is a neurosteroid able to modulate norepinephrine release in the cerebral cortex in an estrous cycle-dependent manner, and that the effect could involve noradrenergic alpha-2 receptors.
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    Synthesis of proteoglycans is augmented in dystrophic mdx mouse skeletal muscle
    (2000) Cáceres, S; Cuellar, C; Casar, JC; Garrido, J; Schaefer, L; Kresse, H; Brandan, E
    Mdx mice uniquely recover from degenerative dystrophic lesions through an intense myoproliferative response. The onset and progression of this process are controlled by a complex set of interactions between myoblasts and their environment. The presence of the extracellular matrix is essential for normal myogenesis. Proteoglycans are abundant components of the extracellular matrix. The synthesis of proteoglycans in mdx mice during skeletal muscle regeneration was evaluated. Incorporation of radioactive sulfate demonstrated a significant increase in the synthesis of several types of proteoglycans in mdx animals compared to age-matched controls. The size and charge of proteoglycans synthesized by the mdx mice remained unchanged. In particular, one of the up-regulated proteoglycans, the small chondroitin/dermatan sulfate proteoglycan decorin which is known to bind and to sequester transforming growth factor-beta, was investigated. Immunocytolocalization and in situ hybridization studies showed that decorin mainly accumulated in the endomysium, i.e. around individual skeletal muscle fibers from M. titialis anterior and diaphragm.