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Biomedical subjects

S Murayama

Publications and source records attributed to S Murayama.

At least 253 records · Page 14Linked to original sources
PubMed1980

Effect of the serotonergic system on the caudate nucleus.

Effects of L-5-hydroxytryptophan (L-5HTP), an active precursor of 5-hydroxytryptamine (5-HT), and electrical stimulation of the dorsal raphe nucleus were observed on the activity of the caudate nucleus in cats with electroencephalographic and evoked potential studies. In an electroencephalographic study, thecaudate spindle and the VA spindle, recorded in the cerebral cortex and induced by electrical stimulation of the caudate nucleus and the anterior ventral nucleus, respectively, were inhibited by L-5HTP. The inhibitory effect of L-5HTP on the caudate spindle was stronger than that on the VA spindle. These inhibitory effects of L-5HTP were observed when L-5HTP showed synchronization on spontaneous EEG and no effect on the duration of the cortical after discharge. In the evoked potential study, both electrical stimulation of the dorsal raphe nucleus and exogenous L-5HTP inhibited the activity of the potentials in the caudate nucleus induced by electrical stimulation of the radial nerve. These results suggest that the neuronal activity of the caudate nucleus is inhibited by the serotonergic system.

5-Hydroxytryptophan↗
PubMed1979

Involvement of the serotonergic system in depression of the caudate spindle.

The involvement of the serotonergic system on the caudate spindle recorded from the posterior sigmoid gyrus was examined in cats. L-5-Hydroxytryptophan injected intravenously inhibited the caudate spindle significantly. On the other hand, the caudate spindle was inhibited by high frequency stimulation of the dorsal raphe nucleus where many serotonergic fibers originate: this inhibitory effect was antagonized by cyproheptadine but not by atropine. These results suggest an involvement of serotonergic mechanisms in depression of the caudate spindle.

5-Hydroxytryptophan↗
PubMed1979

[Neuropharmacological studies on tolperisone hydrochloride (author's transl)].

Neuropharmacological properties of tolperisone hydrochloride (2,4'-dimethyl-3-piperidinopropiophenone hydrochloride) were investigated in mice, rats and cats. Tolperisone inhibited the spontaneous movement and methamphetamine-induced hyperactivity in mice and the ED50 was approx. 50 mg/kg, s.c. At this dose, tolperisone did not prolong the pentobarbital-induced sleeping time. Tolperisone inhibited convulsions induced by pentylenetetrazol, nicotine and maximum electric shock, but did not affect convulsions induced by strychnine and picrotoxin. Tolperisone induced muscle relaxation in mice and rats in several pharmacological tests, but did not affect neuro-muscular transmission. Tolperisone did not affect conditioned avoidance response in rats and methamphetamine-induced rotational behaviour in nigro-lesioned rats. Tolperisone reduced decerebrated rigidity in cats with i.v. administration of 5 approximately 10 mg/kg and intraduodenal administration of 50 approximately 100 mg/kg. Tolperisone elicited a slight drowsy pattern in the spontaneous EEG of cats at 5 approximately 10 mg/kg, i.v., and inhibited the EEG arousal response and pressor response to stimulation of mesencephalic reticular formation or posterior hypothalamic area. These results suggest that inhibition of the activity in the gamma pathway descending from the mesencephalic reticular formation may be involved in the mechanism of muscle relaxant action of tolperisone.

Animals↗
PubMed1976

[Neuropharmacological studies of perimetazine].

Neuropharmacological studies were undertaken to investigate the mode of action of perimetazine. 1) Sedation, hypothermia, muscle relaxation and other signs of central depressant effects were observed after perimetazine administration in the rabbit. 2) Neuro-muscular transmission was not affected by intravnous injection of perimetazine, but was slightly facilitated by a large dose of intraarterial injection of the drug 3) Perimetazine slightly depressed spinal reflex potentials in the spinal cat and markedly reduced them in the anaesthetized cat and the decerebrate cat. 4) Permetazine reduced decerebrate rigidity in the rabbit, and decreased muscle spindle discharges in the decrebrate cat. 5) Perimetazine had no effect on the response of superior cervical ganglion but suppressed the response of the cat nictitating membrane. 6) In the rabbit, perimetazine elicited a drowsy pattern in the spontaneous EEG and inhibited the EEG arousal response induced by auditory stimulation, but failed to depress the EEG arousal response induced by electric stimulation of the mesencephalic reticular formation. These results suggest that perimetazine has central nervous system depressent effects such as sedative and muscle relaxant effects, and its mode of action is similar to that of chlorpromazine.

Animals↗