Deep brain stimulation of the subthalamic nucleus reverses oral tremor in pharmacological models of parkinsonism: Interaction with the effects of adenosine A_2A antagonism

Deep brain stimulation (DBS) of the subthalamic nucleus is increasingly being employed as a treatment for parkinsonian symptoms, including tremor. The present studies used tremulous jaw movements, a pharmacological model of tremor in rodents, to investigate the tremorolytic effects of subthalamic DBS in rats. Subthalamic DBS reduced the tremulous jaw movements induced by the dopamine D₂ family antagonist pimozide and the D₁ family antagonist ecopipam, as well as the cholinomimetics pilocarpine and galantamine. The ability of DBS to suppress tremulous jaw movements was dependent on the neuroanatomical locus being stimulated (subthalamic nucleus vs. a striatal control site), as well as the frequency and intensity of stimulation used. Importantly, administration of the adenosine A_2A receptor antagonist MSX-3 reduced the frequency and intensity parameters needed to attenuate tremulous jaw movements. These results have implications for the clinical use of DBS, and future studies should determine whether adenosine A_2A antagonism could be used to enhance the tremorolytic efficacy of subthalamic DBS at low frequencies and intensities in human patients.