Serotonin modulates pallidal neuronal activity in the awake monkey

Hitoshi Kita, Satomi Chiken, Yoshihisa Tachibana, Atsushi Nambu

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Serotonin (5-HT)-containing neurons in the dorsal raphe project to the external and internal segments of the pallidum, which express several 5-HT receptors. Although the involvement of 5-HT in basal ganglia movement control has been suggested, little is known about the physiological action of 5-HT in the pallidum. Previous anatomical studies and in vitro physiological studies in other brain areas have suggested the following possibilities: (1) 5-HT suppresses GABAergic inhibition through presynaptic 5-HT 1B receptors; (2) 5-HT decreases the firing of pallidal neurons through postsynaptic 5-HT 1A receptors; and (3) 5-HT postsynaptically excites pallidal neurons through activation of 5-HT 2C, 5-HT 4, or 5-HT 7 receptors. To test these possibilities, we examined the effects of locally applied agonists and antagonists of 5-HT on spontaneous neuronal firing and on excitatory and inhibitory responses of pallidal neurons to electrical stimulation of the motor cortex in awake monkeys. Although in vivo experiments could not conclusively determine the receptor types or the active sites involved in the observed effects, the results suggested the following possibilities: (1) 5-HT strongly suppresses GABAergic inhibition probably through 5-HT 1B receptors; (2) in the external pallidal segment, the suppression may involve additional receptors or mechanisms; and (3) 5-HT suppresses glutamatergic excitation probably through 5-HT 1A (and not 5-HT 1B) receptors. The present study did not isolate or identify the existence of strong, direct postsynaptic inhibitory or excitatory effects of 5-HT. Thus, present results imply that 5-HT modulates synaptic inputs of both pallidal segments and exerts a significant role in movement control.

Original languageEnglish (US)
Pages (from-to)75-83
Number of pages9
JournalJournal of Neuroscience
Volume27
Issue number1
DOIs
StatePublished - Jan 3 2007

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Haplorhini
Serotonin
Receptor, Serotonin, 5-HT1B
Neurons
Globus Pallidus
Serotonin Receptors
Serotonin Receptor Agonists
Serotonin Antagonists
Receptor, Serotonin, 5-HT1A
Motor Cortex
Basal Ganglia
Electric Stimulation
Catalytic Domain

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)

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Serotonin modulates pallidal neuronal activity in the awake monkey. / Kita, Hitoshi; Chiken, Satomi; Tachibana, Yoshihisa; Nambu, Atsushi.

In: Journal of Neuroscience, Vol. 27, No. 1, 03.01.2007, p. 75-83.

Research output: Contribution to journalArticle

Kita, Hitoshi ; Chiken, Satomi ; Tachibana, Yoshihisa ; Nambu, Atsushi. / Serotonin modulates pallidal neuronal activity in the awake monkey. In: Journal of Neuroscience. 2007 ; Vol. 27, No. 1. pp. 75-83.
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