Regulation of central synaptic transmission by 5-HT(1B) auto- and Heteroreceptors

Hitoshi Morikawa, Olivier J. Manzoni, John Jr Crabbe, John Williams

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Abstract

Although 5-HT(1B) receptors are believed to be expressed on nerve terminals, their precise mode of action is not fully understood because of the lack of selective antagonists. The 5-HT(1B) receptor knockout mouse was used in the present investigation to assess the function of 5-HT(1B) receptors in the modulation of synaptic transmission in three areas of the central nervous system: the dorsal raphe, the ventral midbrain, and the nucleus accumbens. N-(3-Trifluoromethylphenyl)piperazine, a 5-HT(1B) receptor agonist, potently inhibited 5-HT(1A) receptor-mediated slow inhibitory postsynaptic potentials (IPSPs) in the dorsal raphe of wild-type but not knockout mice. Both synaptically released 5-HT and exogenous 5-HT caused a presynaptic inhibition that outlasted the postsynaptic hyperpolarization only in wild-type mice. In the ventral midbrain, 5-HT(1B) receptor-dependent inhibition of γ-aminobutyric acid(B) IPSPs in dopamine neurons was present in wild-type animals and absent in knockout animals. Similar results were obtained in the nucleus accumbens measuring glutamate-mediated excitatory postsynaptic currents in medium spiny neurons. Finally, cocaine, which blocks 5-HT uptake, inhibited IPSPs in the dorsal raphe and the ventral midbrain of wild-type but not knockout mice, whereas cocaine produced comparable inhibition of excitatory postsynaptic currents in the nucleus accumbens of both types of animals. These results indicate that 5-HT(1B) receptors function as autoreceptors and heteroreceptors to exert presynaptic inhibition of transmitter release in the central nervous system. Furthermore, this study underscores the role played by presynaptic 5-HT(1B) receptors in mediating the effects of cocaine on synaptic transmission.

Original languageEnglish (US)
Pages (from-to)1271-1278
Number of pages8
JournalMolecular Pharmacology
Volume58
Issue number6
StatePublished - 2000

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ASJC Scopus subject areas

  • Pharmacology

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