PT  - JOURNAL ARTICLE
AU  - TSUI-CHIN TSENG
AU  - S. C. WANG
TI  - LOCUS OF ACTION OF CENTRALLY ACTING MUSCLE RELAXANTS, DIAZEPAM AND TYBAMATE
DP  - 1971 Aug 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 350--360
VI  - 178
IP  - 2
4099  - http://jpet.aspetjournals.org/content/178/2/350.short
4100  - http://jpet.aspetjournals.org/content/178/2/350.full
SO  - J Pharmacol Exp Ther1971 Aug 01; 178
AB  - Diazepam and tybamate have previously been reported to depress spinal polysynaptic reflexes. The dose-response relationships for depressant actions of diazepam and tybamate on contralateral extensor reflexes were studied in midcollicular and acute spinal cats. The reflexes were readily depressed by small doses of diazepam in midcollicular preparations, whereas very large doses (100-fold) were required in spinal preparations. On the other hand, the doseresponse curves of tybamate-induced depression were practically identical in these two preparations. The effects of graded doses of diazepam and tybamate on mesencephalic reticular and spinal internuncial neuronal activity were also studied. Whereas approximately 0.05 mg/kg of diazepam was required to decrease the reticular neuronal activity 50%, 0.4 mg/kg was required to reduce spinal interneuronal activity to the same extent. These findings suggest that the major site of action of diazepam is the brainstem reticular system. Tybamate was found to act equally on the reticular neurons and spinal interneurons. It appears, however, that the spinal interneuronal site of action of tybamate alone may adequately explain the depression of spinal polysynaptic reflexes. © 1971 by The Williams & Wilkins Co.