Folia Pharmacologica Japonica
Online ISSN : 1347-8397
Print ISSN : 0015-5691
ISSN-L : 0015-5691
Volume 96, Issue 1
Displaying 1-4 of 4 articles from this issue
  • Hideomi FUKUDA, Hideki ONO
    1990 Volume 96 Issue 1 Pages 1-9
    Published: 1990
    Released on J-STAGE: February 20, 2007
    JOURNAL FREE ACCESS
    The physiological function of the descending noradrenergic system in the spinal ventral horn has not yet been fully elucidated. Here we describe our recent findings showing the motor function of the noradrenergic fibers. 1) α1-Antagonists and α2-agonists depressed the spinal mono and polysynaptic reflex potentials in rats that have an intact connection between the spinal cord and the brain. In rats spinalized at the Cl level, the α1-agonistic action of adrenergic agents increased the spinal reflexes. 2) In the radio frequency-lesioned decerebrate rigidity model of rats, α1-antagonists and α2-agonists reduced the rigidity by affecting the spinal and supraspinal levels, respectively. 3) α2-Agonists but not α1-antagonists reduced noradrenaline released into the subarachnoid space of anesthetized rats. 4) In a slice preparation isolated from adult rats, the α1-agonistic action of adrenergic agents increased the excitatory synaptic transmission of the ventral horn. Thus, it was demonstrated that α2-agonistic action at the brain stem inhibited spinal motor activity by reducing the release of noradrenaline in the spinal cord, and that the facilitatory action through α1-adrenoceptors was dominant in descending noradrenergic transmission in the motor nuclei of the ventral horn.
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  • Katsuya YAMASAKI, Yoshiaki GOTO
    1990 Volume 96 Issue 1 Pages 11-21
    Published: 1990
    Released on J-STAGE: February 20, 2007
    JOURNAL FREE ACCESS
    The effects of 2-(p-chlorophenyl)-GABA (PCPGABA), thyrotropine releasing hormone (TRH), insulin and 2-deoxy-D-glucose (2DG) on gastric acid secretion, vagal nerve efferent activity and blood glucose level were. examined in anesthetized rats. The latencies of onset of hypersecretion were 10 min for TRH (1 μg/rat, i.c.), 20 min for PCPGABA (4 mg/kg, s.c.), 60 min for 2DG (200 mg/kg, i.v.) and 90 min for insulin (2 U/kg, i.v.), respectively. The secretagogue actions of PCPGABA and TRH were more potent than those of 2DG and insulin. All these secretagogues caused the efferent activation of the cervical vagal transmission, and the latencies for these vagal activation were shorter than those seen in gastric acid hypersecretion. Atropine and vagotomy completely abolished the secretagogue actions of these stimulants. PCPGABA and TRH were ineffective on the blood glucose level, unlike insulin and 2DG. These results suggest that PCPGABA, TRH, 2DG and insulin stimulate gastric acid secretion via central vagal cholinergic pathways, even though the precise mechanisms for each stimulant seem to be different.
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  • Nobuhiko YAMAZAKI
    1990 Volume 96 Issue 1 Pages 23-30
    Published: 1990
    Released on J-STAGE: February 20, 2007
    JOURNAL FREE ACCESS
    This study was undertaken to elucidate the relationship between natriuresis and renally formed dopamine in pentobarbital-anesthetized rats that were loaded with 0.9% NaCl. Infusion of dopamine resulted in marked increases in urinary free dopamine excretion, plasma free dopamine concentration, urine volume and urinary sodium excretion. Infusion of carbidopa markedly decreased urinary free dopamine excretion, but did not affect urine volume and urinary sodium excretion. Infusion of L-dopa markedly increased urinary free dopamine excretion and plasma free dopamine concentration, but did not affect urine volume and urinary sodium excretion. When carbidopa was infused with L-dopa or dopamine, carbidopa significantly inhibited the increase in urinary and plasma free dopamine induced by L-dopa, but did not inhibit the increases in urinary and plasma free dopamine, urinary sodium excretion and urine volume induced by dopamine. These data indicated that there is no correlation between renally formed dopamine and natriuresis, and furthermore suggested that renally formed dopamine is not essential for natriuresis.
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  • Kinzo MATSUMOTO, Bing CAI, Shinya NAKAMURA, Hiroshi WATANABE
    1990 Volume 96 Issue 1 Pages 31-39
    Published: 1990
    Released on J-STAGE: February 20, 2007
    JOURNAL FREE ACCESS
    To estimate the spontaneous motor activity in mice, a new system with highly stable sensitivity and good reproducibility was made, and the effects of five central stimulants were investigated. The apparatus consists of a doughnut-shaped cage with detectors for measuring spontaneous motor activity; i.e., the number of movements, vertical activity, total distance, etc., for every five min. Methamphetamine (0.5, 1 and 2 mg/kg, s.c.) produced an increase in the number of movement and markedly increased total distance. Cocaine (20, 50 and 75 mg/kg, s.c.) caused a marked increase in movement and total distance. Mice injected with 50 mg/kg of cocaine showed long-lasting locomotion with few stops throughout the observation period. Caffeine (10, 30 and 100 mg/kg, s.c.) produced a long-lasting and moderate excitation. Morphine (5, 10 and 20 mg/kg, s.c.) caused a marked increase in continuous locomotion dose-dependently. Apomorphine produced a transient increase in rearing and locomotion at a dose of 1 mg/kg, s.c.; and it produced long-lasting rearing and moderate locomotor activity at 3 mg/kg. These results suggest that this apparatus is able to detect characteristic changes in spontaneous motor activity produced by central stimulants and may be useful for analyzing drug-induced motor activity in mice in more detail.
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