Possible Roles of Kainate Receptors on GABAergic Nerve Terminals Projecting to Rat Substantia Nigra Dopaminergic Neurons
| Autor: | Norio Akaike, Shigenori Watanabe, Michiko Nakamura, Il-Sung Jang, Hitoshi Ishibashi |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
Neurons
Dose-Response Relationship Drug Physiology Pars compacta Dopamine General Neuroscience Dopaminergic Presynaptic Terminals Action Potentials Kainate receptor Substantia nigra In Vitro Techniques Biology Rats Substantia Nigra Receptors GABA Receptors Kainic Acid Afferent Neural Pathways Animals GABAergic Rats Wistar Neuroscience |
| Zdroj: | Journal of Neurophysiology. 90:1662-1670 |
| ISSN: | 1522-1598 0022-3077 |
| DOI: | 10.1152/jn.01165.2002 |
| Popis: | GABAergic afferent inputs are thought to play an important role in the control of the firing pattern of substantia nigra pars compacta (SNc) dopaminergic neurons. We report here the actions of presynaptic kainite (KA) receptors in GABAergic transmission of rat SNc dopaminergic neurons. In mechanically dissociated rat SNc dopaminergic neurons attached with native presynaptic nerve terminals, GABAergic miniature inhibitory postsynaptic currents (mIPSCs) were recorded by use of conventional whole cell patch recording mode. In the voltage-clamp condition, KA (3 μM) significantly increased GABAergic mIPSC frequency without affecting the current amplitude. This facilitatory effect of KA was not affected in the presence of 20 μM GYKI52466, a selective AMPA receptor antagonist, but was completely inhibited in the presence of 20 μM CNQX, an AMPA/KA receptor antagonist. Presynaptic KA receptors on GABAergic terminals were mainly permeable to Na+ but impermeable to Ca2+ because KA-induced facilitation of mIPSC frequency was completely suppressed in either Na+-free or Ca2+-free external solutions, and in the presence of 200 μM Cd2+, a general voltage-dependent Ca2+ channel blocker. In the slice preparation, KA increased GABAergic spontaneous mIPSC frequency, but significantly suppressed evoked IPSC (eIPSC) amplitude. However, this inhibitory action on eIPSCs was reversed by 10 μM CGP55845 , a selective GABAB receptor antagonist, implicating the possible involvement of GABAB autoreceptors in KA-induced modulation of GABAergic transmission. Thus presynaptic KA receptors on GABAergic nerve terminals synapsing onto SNc neurons may play functional roles contributing the fine control of neuronal excitability and firing pattern of SNc. |
| Databáze: | OpenAIRE |
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