Enhancement by serotonin of GABA-mediated inhibitory synaptic currents in rat cerebellar Purkinje cells.
The actions of serotonin (5-HT) on synaptic responses in Purkinje cells were examined using the whole-cell voltage-clamp recording from thin slices of the rat cerebellum. Focal stimulation within the molecular layer elicited synaptic responses: (1) inhibitory postsynaptic currents (IPSCs) that were completely blocked by bicuculline; (2) excitatory postsynaptic currents (EPSCs) that were antagonized by CNQX; and (3) combination of IPSC and EPSC. Application of 5-HT (3-30 microM) increased the amplitude of the stimulation-evoked IPSCs but did not significantly affect the EPSCs. The frequency and the mean amplitude of spontaneous IPSCs were increased in the presence of 5-HT. Neither the sensitivity to exogenously applied GABA nor the holding current of Purkinje cells were noticeably altered by 5-HT. The results indicate that 5-HT differentially enhances the GABA-mediated IPSCs in rat cerebellar Purkinje cells via a presynaptic mechanism. Serotonergic neurons thus appear to play a role in the motor control through selective presynaptic facilitation that modulates the output from the cerebellar cortex.
Mitoma
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Department of Neuroscience, Mitsubishi Kasei Institute of Life Sciences, Tokyo, Japan.
Kobayashi
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T
Song
S Y
SY
Konishi
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D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D002531:Cerebellum / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D004594:Electrophysiology; D011689:Purkinje Cells / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D012701:Serotonin / Q000494:pharmacology*; D013569:Synapses / Q000187:drug effects* / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
D012701:Serotonin; D005680:gamma-Aminobutyric Acid; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D001640:Bicuculline