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Biomedical subjects

T Shima

Publications and source records attributed to T Shima.

At least 217 records · Page 12Linked to original sources
PubMed1979

[Thyrotropin-releasing hormone (TRH): Enhancement of dopamine dependent circling behavior and its own circling-inducing effect in unilateral striatal lesioned animals (author's transl)].

Enhancement by TRH of the dopamine(DA) agonist-induced circling behavior and effect of TRH itself on circling behavior were investigated. TRH(2.5--20 mg/kg, i.p.) remarkably enhanced the circling behavior induced by apomorphine or-L-DOPA in the mice lesioned unilaterally in the caudate nucleus by injection of 6-hydroxydopamine (60OHDA) or by tissue aspiration with subsequent reserpinization. TRH also enhanced the apomorphine-induced stereotypy in reserpinized normal mice. The above TRH-enhancing action of the circling behavior was potentiated, suppressed or unaffected by alpha-methyl-para-tyrosine (alpha-MT) or GABA-ergic drugs. In the 6-OHDA lesioned mice treated with TRH, the cyclic AMP formation by DA or apomorphine was clearly enhanced in the triatal slices taken from the lesioned side but not from the intact side. In the rats lesioned unilaterally in the nigrostriatal DA pathway by 6-OHDA, high doses of TRH injected i.p. (100 mg/kg) or into the non-lesioned caudate nucleus (50 micrograms) produced circling toward the lesioned side, which was suppressed by haloperidol or alpha-MT. TRH(10(-5)--10(-3)M) increased the 14C-DA release from the rat striatal slices in vitro. These results suggest that TRH at low doses facilitates the DA postsynaptic transmission in association with an increase of DA-stimulated cyclic AMP formation in the striatum under supersensitization of the DA receptors, and also at high doses enhances the DA neuronal activity by increasing the DA release from the striatal nerve terminals.

Animals↗
PubMed1979

Neuromuscular blocking potency of fazadinium in man.

The study was designed to compare the recovery rates of fazadinium and four other commonly used competitive muscle relaxants in forty patients and eight volunteers. One-fifth to 1/10 of the clinical doses of the muscle relaxants were diluted in 20 ml of saline and injected intravenously at the wrist after inflation of a pneumatic tourniquet on the upper arm. After 3 min the tourniquet was released and the recovery time of twitch tension from 25 to 75% of the control determined. Evoked force of middle finger adduction was measured at a frequency of 0.2 Hz. The mean 25-75% recovery times of twitch tension for tubocurarine, pancuronium, alcuronium, gallamine and fazadinium were 14.20 +/- 1.42, 12.30 +/- 1.02, 10.12 +/- 0.77, 10.07 +/- 1.12 and 9.90 +/- 0.87 min, respectively. The authors conclude that the dissociation rate of fazadinum from the receptor of the motor endplate appears to be the fastest among the competitive muscle relaxants studied in man.

Adolescent↗
PubMed1979

Thyrotropin-releasing hormone: hyperactivity and mesolimbic dopamine system in rats.

The mechanism of stimulatory action of thyrotropin-releasing hormone (TRH) on spontaneous motor activity was investigated in rats. TRH produced a significant hyperactivity with intraperitoneal administration of 20 mg/kg or bilateral injection of 10 micrograms into the nucleus accumbens septi (NAS). Following bilateral injection of 6-hydroxydopamine into the mesolimbic dopamine (DA) pathway, the hyperactivity induced by TRH was not altered, whereas the response to apomorphine given intraperitoneally or DA injected into the NAS was clearly enhanced. The TRH-induced hyperactivity was remarkably suppressed by alpha-methyltyrosine and in contrast, augmented by pargyline. Systemic injection of aminooxyacetic acid in a dose producing behavioral depression reduced markedly the TRH-induced hyperactivity. Bilateral injection of ethanolamine O-sulphate (100 micrograms) into the NAS produced no behavioral depression per se, but remarkably attenuated the hyperactivity response to TRH or DA (20 micrograms) given intraperitoneally or into the NAS. Both TRH (10(-5) and 10(-4) M) and methamphetamine (10(-6)--10(-4) M increased the spontaneous release of 14C-DA from rat NAS slices. These findings suggest that TRH induces hyperactivity by enhancing DA release from nerve terminals in the NAS without a direct stimulation of the post-synaptic DA recptors. TRH and GABA, independently or via interaction between them, may play a reciprocal regulatory role in the activity of the mesolimbic DA system.

Animals↗
PubMed1979

Neuromuscular blocking property of minocycline in the rabbit.

The neuromuscular blocking property of minocycline hydrochloride (MNC) was studied in 12 rabbits. In 2 of 6 animals, MNC, 60-160 mg/kg, alone caused a decrease in twitch tension. During partial neuromuscular blockade produced by a continuous infusion of pancuronium, the intravenous administration of MNC, 20--60 mg/kg, resulted in a dose-dependent decrease in twitch tension in 6 animals. MNC-induced or combined MNC-pancuronium-induced neuromuscular blockade was antagonized by calcium or by neostigmine.

Animals↗