Effects of an antispastic drug [β-(4-chlorophenyl)-γ-aminobutyric acid] on Renshaw cell activity

Abstract

Lioresal ® [β-(4-chlorophcnyl)-γ-aminobutyric acid, 1–25 mg kg i.v.] caused a marked increase of Renshaw cell activity in cats when Renshaw cell responses were tested by antidromic stimulation of motor nerve fibres. Lioresal lowered the threshold, enhanced the frequency of the early response, and prolonged its firing period. The drug also increased or induced spontaneous Renshaw cell activity. These activating effects were present in intact anaesthetized and m decerebrated cats as well as in spinalized cats. From the results it can be expected that the increased Renshaw cell activity leads to an augmented recurrent inhibition of α-motoneurones. It is suggested that this mechanism acting at spinal level explains in part the beneficial effect of Lioresal in therapy of spinal spasticity.