title: Balance of monosynaptic excitatory and disynaptic inhibitory responses of the globus pallidus induced after stimulation of the subthalamic nucleus in the monkey.
abstract: The subthalamic nucleus (STN) plays a pivotal role in controlling the activity of both the external and internal segments of the globus pallidus (GPe and GPi, respectively). Both nuclei receive monosynaptic excitatory and disynaptic GPe-mediated inhibitory inputs from the STN. Thus, we investigated the balance of these antagonistic inputs that may determine the overall response of pallidum to STN activation in monkeys. Single stimulation of the STN evoked a short-latency excitation followed by a weak inhibition in GPe neurons and a short-latency, very short-duration excitation followed by a strong inhibition in GPi neurons. Burst high-frequency stimulation (BHFS) (10 stimuli with 100 Hz) of the STN (STN-BHFS) evoked powerful excitatory responses in GPe neurons. Local injection of a mixture of 1, 2, 3, 4-tetrahydro-6-nitro-2, 3-dioxobenzo[f]quinoxaline-7-sulfonamide (NBQX; AMPA/kainate receptor blocker) and 3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP; NMDA receptor blocker) greatly diminished or abolished excitatory responses to the STN stimulation. In contrast to the GPe, STN-BHFS evoked a predominantly inhibitory response in GPi neurons. The inhibition could be blocked either by a local application of the GABAA receptor antagonist gabazine or by an injection of an NBQX/CPP/gabazine mixture into the GPe. STN-BHFS induced weak excitatory or inhibitory responses in a small number of phasically active putamen neurons. These data suggest that with single stimulation and during STN-BHFS, the STN-GPe excitatory response dominates over the STN-GPe-GPe recurrent inhibition in the GPe, whereas the STN-GPe-GPi inhibitory response dominates over the STN-GPi excitatory response in the GPi.
authors.affiliation: Department of Anatomy and Neurobiology, College of Medicine, University of Tennessee, Memphis, Tennessee 38163, USA. hkita@utmem.edu
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kita
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Tachibana
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nambu
authors.forename: Satomi
authors.initials: S
authors.lastname: Chiken
mesh_terms: D000818:Animals; D004558:Electric Stimulation / Q000379:methods; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005917:Globus Pallidus / Q000187:drug effects / Q000502:physiology*; D008253:Macaca mulatta; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D020531:Subthalamic Nucleus / Q000187:drug effects / Q000502:physiology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*
chemical_list: D018691:Excitatory Amino Acid Antagonists