Abstract
As a part of the research on the mechanisms of action of the centrally acting muscle relaxants, the tentative correlation between the effect on the polysynaptic reflex and gamma-aminobutyric acid (GABA) level in the spinal cord was studied in young chicks. The spinal GABA concentration of chicks was found to be 12.1 mg/100 g wet tissue. The spinal GABA level was not significantly altered by several relaxants and stimulants. It was found that amino-oxyacetic acid (AOAA), an inhibitor of GABA transaminase, markedly increased the spinal GABA level in chicks. The inhibitory effect of mephenesin or exogenous GABA on the crossed extensor reflex in AOAA-pretreated chicks was not significantly different from that in AOAA-untreated ones. Consequently, evidence for the direct correlation between the action of the centrally acting muscle relaxant and the GABA level in the spinal cord could not be obtained.
