The effect of baclofen on the hind limb flexor reflex of the spinal rat

The effect of baclofen on the hind limb flexor reflex of the spinal rat was studied. Baclofen inhibited the flexor reflex, this effect not being antagonized by picrotoxin and bicuculline. Baclofen reduced the stimulating action of quipazine and LSD, had no effect on the clonidine-induced reflex stimulation, but inhibited the flexor reflex stimulation induced by amphetamine and fenfluramine. The results obtained bring forth some doubts as to the GABA-mimetic action of baclofen. The action of baclofen on the spinal cord seems to be directed mainly to the presynaptic part of the noradrenergic and serotonergic systems.