Browsing by Author "TORRES, G"

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    AGE AND CASTRATION MODULATE THE INHIBITORY-ACTION OF NEUROPEPTIDE-Y ON NEUROTRANSMISSION IN THE RAT VAS-DEFERENS
    (1991) BITRAN, M; TORRES, G; FOURNIER, A; STPIERRE, S; HUIDOBROTORO, JP
    The potency of neuropeptide Y (NPY) to inhibit the electrically induced contractions of the epididymal half of the vas deferens diminishes markedly with age, being at least 20 times lower in the adult than in the 26-day-old rat. Castration sensitizes the epididymal segment to NPY in a testosterone-reversible manner. [Pro34]NPY was 3 times less potent than NPY in prepubertal rats and inactive in castrated adults, while NPY-(13-36) had no effect in either group. In the prostatic half, NPY and its analogs were active in rats from all ages studied; the order of potency being NPY > [Pro34]NPY > NPY-(13-36). The sensitivity of the prostatic segment from adult rats to NPY was unchanged by castration or testosterone replacement therapy. The NPY content of the ductus increases during development being higher in,the prostatic than in the epididymal half at all ages studied. Castration decreases the peptide content in the two segments and the effect is prevented by testosterone administration. The present investigation demonstrated that the effect of NPY on vas deferens neurotransmission is subject to regulation by sex steroids, which affects differently the response of the two segments of the ductus.
  • No Thumbnail Available
    Item
    CORELEASE OF NEUROPEPTIDE-Y (NPY) AND NORADRENALINE FROM THE SYMPATHETIC-NERVE TERMINALS SUPPLYING THE RAT VAS-DEFERENS - INFLUENCE OF CALCIUM AND THE STIMULATION INTENSITY
    (1992) TORRES, G; BITRAN, M; HUIDOBROTORO, JP
    Epididymal (E) and prostatic (P) segments of the rat vas deferens were incubated with tritium-labeled noradrenaline (NA); upon transmural electrical stimulation for 20 or 60 s (70 V, 1 ms, 3-35 Hz), the outflow of immunoreactive neuropeptide Y (ir-NPY) and NA was detected in the superfusion media. Ir-NPY was detected only following trains of 35 Hz for 60 s in both E and P. In contrast, tritium was released in a graded fashion following trains of 3, 15 or 35 Hz stimulation for 60 s in E, whereas in P it reached a plateau at frequencies larger than 15 Hz. The outflow of tritium, under present conditions, was dependent on the duration of the stimuli, while the release of ir-NPY was only evoked with stimuli of 60 s duration. In the absence of external Ca2+, neurotransmission was blocked and co-release of ir-NPY and NA was prevented.
  • No Thumbnail Available
    Item