Serotonin activates presynaptic and postsynaptic receptors in rat globus pallidus

Kenji Hashimoto, Hitoshi Kita

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

Although recent histological, behavioral, and clinical studies suggest that serotonin (5-HT) plays significant roles in the control of pallidal activity, only little is known about the physiological action of 5-HT in the pallidum. Our recent unit recording study in monkeys suggested that 5-HT provides both presynaptic and postsynaptic modulations of pallidal neurons. The present study using rat brain slice preparations further explored these presynaptic and postsynaptic actions of 5-HT. Bath application of 5-HT or the 5-HT 1A/1B/1D/5/7 receptor (R) agonist 5-carboxamidotryptamine maleate (5-CT) depolarized some and hyperpolarized other pallidal neurons. Pretreatments of slices with blockers of the hyperpolarization- cyclic nucleotide-activated current or with the 5-HT 2/7R-selective antagonist mesulergine occluded 5-CT-induced depolarization. The 5-HT 1AR-selective blocker N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-2- pyridinylcyclohexanecarboxamide maleate occluded the 5-CT-induced hyperpolarization. These results suggested involvement of 5-HT 7R and 5-HT 1AR in the postsynaptic depolarization and hyperpolarization, respectively. 5-CT presynaptically suppressed both internal capsule stimulation-induced excitatory postsynaptic currents (EPSCs) and striatal stimulation-induced inhibitory postsynaptic currents (IPSCs). The potencies of 5-CT on the presynaptic effects were 20- to 25-fold higher than on postsynaptic effects, suggesting that 5-HT mainly modulates presynaptic sites in the globus pallidus. Experiments with several antagonists suggested involvement of 5-HT 1B/DR in the presynaptic suppression of EPSCs. However, the receptor type involved in the presynaptic suppression of IPSCs was inconclusive. The present results provided evidence that 5-HT exerts significant control over the synaptic inputs and the autonomous activity of pallidal neurons.

Original languageEnglish (US)
Pages (from-to)1723-1732
Number of pages10
JournalJournal of Neurophysiology
Volume99
Issue number4
DOIs
StatePublished - Apr 1 2008

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Presynaptic Receptors
Globus Pallidus
Serotonin
Inhibitory Postsynaptic Potentials
Excitatory Postsynaptic Potentials
Neurons
Internal Capsule
Corpus Striatum
Cyclic Nucleotides
Baths

All Science Journal Classification (ASJC) codes

  • Physiology
  • Neuroscience(all)

Cite this

Serotonin activates presynaptic and postsynaptic receptors in rat globus pallidus. / Hashimoto, Kenji; Kita, Hitoshi.

In: Journal of Neurophysiology, Vol. 99, No. 4, 01.04.2008, p. 1723-1732.

Research output: Contribution to journalArticle

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