[The effect of DOPA on the reciprocal inhibition of the innervation centers of antagonistic muscles in newborn rat pups].

In experiments on 5--7- and 16-day rat puppies with acute lesion of the spinal cord, by means of monosynaptic tests, studies have been made of the effect of DOPA on reciprocal inhibition of antagonist muscles. Test stimuli were applied to n. tibialis, conditioned ones--to n. peroneus. It was shown that the pattern of the effects depends on the action of the drug on the magnitude of the initial monosynaptic reflex used as a test. It the latter was initially inhibited, the conditioned stimulation resulted within the first 1-8 msec not in the development of postsynaptic inhibition, but in evident facilitation, which was longer in 5--7-day animals. The level of presynaptic inhibition was somewhat lower than the initial one, but exhibited longer duration. In case of facilitation of a control test after DOPA injection, configuration of reciprocal inhibition curves did not significantly differ from that obtained before administration of the drug.