THE IMPORTANCE OF THE STRIATO-NIGRO-COLLICULAR PATHWAY IN THE EXPRESSION OF HALOPERIDOL-INDUCED TONIC ELECTROMYOGRAPHIC ACTIVITY

The participation of the striatonigral and nigrocollicular GABAergic pathways were investigated in the expression of haloperidol-induced tonic electromyographic (EMG) activity of the gastrocnemius-soleus muscle in awake rats. Bilateral injections of haloperidol (500 ng/0.5 .mu.l) into the rostral part of the neostriatum induced a tonic EMG activity which could be significantly reduced by a 2nd bilateral injection of muscimol (25 ng/0.5 .mu.l) into the substantia nigra pars reticulata (SNR) or of bicuculline (50 ng/0.5 .mu.l) into the intermediate or deep layers of the colliculus superior (CS). The striatonigral and nigrocllicular GABAergic pathways play a critical role in the transmission of haloperidol-induced tonic EMG activity.