Induction of mandibular tremor using electrolytic lesion of the ventrolateral striatum or using subchronic haloperidol therapy in male rats: an electromyographic comparison.

INTRODUCTION Tremulous jaw movement (TJMs) in rats can be induced pharmacologically by striatal dopaminergic manipulation or electrolytic lesion of ventrolateral striatum (VLS). This tremor has neurochemical, anatomical and electromyographic (EMG) characteristics similar to those of tremor in Parkinson patients. However, the EMG characteristics of tremors generated by electrolytic lesion to the VLS have not yet been studied. METHOD This study used electromyography to describe tremulous jaw movement generated by bilateral electrolytic lesion in the VLS and compare it to tremors induced using subchronic IP treatment with haloperidol, a dopaminergic D2 receptor antagonist. The experimental groups contained rats with a lesion in the ventrolateral striatum and rats on subchronic haloperidol treatment; the control group received only the vehicle. The EMG signal from the temporal muscle was recorded at baseline and during TJMs in all groups. RESULTS TMJ frequencies were heterogeneous among the groups. Rats with VLS lesion showed higher amplitude and frequency values than the haloperidol-treated rats. Amplitudes at baseline also differed among the groups. CONCLUSIONS We conclude that TMJs associated with electrolytic lesion to the VLS show a higher frequency and amplitude than tremors induced by haloperidol. This may be related to the way striatum neurons are affected.