The influence of dizocilpine (MK-801) on the reserpine-enhanced electromyographic stretch reflex in rats.

The electromyographic (EMG) stretch reflex in the gastrocnemius and tibialis anterior muscles was elicited by passive bending and stretching of the rat's hind foot in the ankle joint. The EMG stretch reflex was increased by pretreatment with reserpine (10 mg/kg ip) which is a model compound commonly used to induce parkinsonian rigidity in laboratory animals. Dizocilpine (MK-801) (0.32, 0.64 and 1.28 mg/kg sc) inhibited long-latency supraspinal components of the reserpine-increased EMG stretch reflex, whereas a short-latency spinal component was not diminished. The present results suggest that MK-801 exhibits an antiparkinsonian action against reserpine-induced rigidity.