Subthalamo-pallido-striatal axis: a feedback system in the basal ganglia

Systemic administration of a dopamine D2 receptor blocker, haloperidol, but not vehicle, significantly increased the number of c-Fos-immunoreactive ne urons in the globus pallidus (GP) in rats. Dual immunohistochemistry, a com bination of c-Fos immunohistochemistry and retrograde tracing experiments w ith cholera toxin B (ChB), revealed that a subset, of the c-Fos-immunoreact ive GP neurons was pallidostriatal feedback neurons. Lesioning of the subth alamic nucleus (STN) by local infection of ibotenic acid inhibited the halo peridol-induced c-Fos expression in the GP neurons, suggesting that the act ivation of GP neurons is a result of increased excitatory drives from the S TN. Therefore, the present findings are evidence of the existence of the su bthalamo-pallido-striatal axis as a feedback system in the internal circuit s of the basal ganglia. NeuroReport 12:3795-3798 (C) 2001 Lippincott Willia ms & Wilkins.