Effects of diazepam on behavior and dopamine-containing substantia nigra units in freely moving cats.

Administration of diazepam at doses that produced ataxia (5-10 mg/kg IP) significantly decreased the discharge rate of substantia-nigral dopamine-containing neurons by 28.1% in freely moving cats. Diazepam also altered the characteristic decremental bursting pattern of these neurons, producing a steady rhythmic discharge pattern. Similar results were obtained with another centrally acting muscle-relaxant drug, mephenesin. However, the peripherally acting muscle relaxant dantrolene did not produce these effects. These data suggest that diazepam and other centrally acting muscle relaxants may produce their effects on motoric behavior in part by altering the dopaminergic input to the striatum.