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207 Aminergic long-term potentiation of cerebellar GABA-mediated inhibitory transmission through camp dependent mechanism
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OMEGA-AGATOXINIVA INSENSITIVE CALCIUM CHANNELS IN RAT CEREBELLAR lSHIGE0 WATANABE, ZHIROSHI TAKAGI, LYUTAKA PURKINJE CELL DENDRITES.
KIRINO, ZHIROYOSHI MIYAKAWA, AND ZYOSHIHISA KUDO, aTokyo University of Pharmacy and Lifescience, Japan.
1The University
of Tokyo,
207
AMINERGIC LONG-TERM POTENTIATION OF CEREBELLAR GABA-MEDIATED INHIBITORY TRANSMISSION THROUGH CAMP DEPENDENT MECHANISM. HIROSHI MITOMA AND SHIRO KONISHI, Mitsubishi Kasei Institute of Life Sciences. 1 1-Minamioova. Machida-shi. Tokvo 194. Janan. Previously we reported that brief single application of serotonin (5-HT) or noradrenaline (NA) produces short-term enhancement of GABA-mediated transmission on Purkinje cells via presynaptic mechanism. This study was undertaken to further examine if the amines cause long-term effects on cerebellar synaptic responses and mechanisms of amine-induced actions. Whole-cell voltage-clamp recordings were made from Purkinje cells in cerebellar slices. Repeated multiple applications of 5-HT and NA switched from short-term potentiation to long-term potentiation of inhibitory postsynaptic currents (IPSCs). This effect lasted for 2 hours after termination of amine application. The aminergic potentiation was mimicked by forskolin and blocked by kinase inhibitors, H-7 and H-89. Repetitive stimulation at 0.1 Hz for 20 min produced long-lasting facilitation of IPSCs, which was prevented by amine receptor antagonists, methiothepin and propranolol. The results suggestthat synaptically released 5-HT and NA activate CAMP-dependent mechanismin GABAergic neuron,therebyeliciting long-termpotent&ion of the inhibitory transmission.
208
DEVELOPMENTAL CHANGES IN GABAERGIC IPSCS RECORDED FROM RAT THALAMIC NEURONS IN SLICE. KAYOKO ONODERA, TOMOYUKI TAKAHASHI Dept. of Neuroohvsiol..Inst. for Brain Research.Fat of Med.. Univ. of Tokvo. Hnneo. Tokvo 11’3.Janan. Developmentalswitching of GABA, receptorsubunitshasbeenreportedto occur during the early postnatalperiod in rat thalamus.To examinewhetherthesechangesmight be reflectedin synapticresponsesmediatedby GABA, receptors, we have recordedGABAergic IPSCs from neuronsin the dorsolateralnucleusof rat thalamusby using a brain slice preparationand the whole-cell patch-clamptechnique.The IPSCsevoked by stimulatingnucleusreticularis thalami and those occurring spontaneouslywere analyzed. During the first postnatalmonth, the decay time of spontaneousand evoked IPSCsbecameprogressivelyshorter,whereasthe rise-timeremainedconstant.We concludethat the fast kinetics of GABAergic IPSCs in mature rat thalamus could be achieved by changesin the expressionof GABA, receptor subunits.
OMEGA-AGATOXINIVA INSENSITIVE CALCIUM CHANNELS IN RAT CEREBELLAR lSHIGE0 WATANABE, ZHIROSHI TAKAGI, LYUTAKA PURKINJE CELL DENDRITES.
KIRINO, ZHIROYOSHI MIYAKAWA, AND ZYOSHIHISA KUDO, aTokyo University of Pharmacy and Lifescience, Japan.
1The University
of Tokyo,
207
AMINERGIC LONG-TERM POTENTIATION OF CEREBELLAR GABA-MEDIATED INHIBITORY TRANSMISSION THROUGH CAMP DEPENDENT MECHANISM. HIROSHI MITOMA AND SHIRO KONISHI, Mitsubishi Kasei Institute of Life Sciences. 1 1-Minamioova. Machida-shi. Tokvo 194. Janan. Previously we reported that brief single application of serotonin (5-HT) or noradrenaline (NA) produces short-term enhancement of GABA-mediated transmission on Purkinje cells via presynaptic mechanism. This study was undertaken to further examine if the amines cause long-term effects on cerebellar synaptic responses and mechanisms of amine-induced actions. Whole-cell voltage-clamp recordings were made from Purkinje cells in cerebellar slices. Repeated multiple applications of 5-HT and NA switched from short-term potentiation to long-term potentiation of inhibitory postsynaptic currents (IPSCs). This effect lasted for 2 hours after termination of amine application. The aminergic potentiation was mimicked by forskolin and blocked by kinase inhibitors, H-7 and H-89. Repetitive stimulation at 0.1 Hz for 20 min produced long-lasting facilitation of IPSCs, which was prevented by amine receptor antagonists, methiothepin and propranolol. The results suggestthat synaptically released 5-HT and NA activate CAMP-dependent mechanismin GABAergic neuron,therebyeliciting long-termpotent&ion of the inhibitory transmission.
208
DEVELOPMENTAL CHANGES IN GABAERGIC IPSCS RECORDED FROM RAT THALAMIC NEURONS IN SLICE. KAYOKO ONODERA, TOMOYUKI TAKAHASHI Dept. of Neuroohvsiol..Inst. for Brain Research.Fat of Med.. Univ. of Tokvo. Hnneo. Tokvo 11’3.Janan. Developmentalswitching of GABA, receptorsubunitshasbeenreportedto occur during the early postnatalperiod in rat thalamus.To examinewhetherthesechangesmight be reflectedin synapticresponsesmediatedby GABA, receptors, we have recordedGABAergic IPSCs from neuronsin the dorsolateralnucleusof rat thalamusby using a brain slice preparationand the whole-cell patch-clamptechnique.The IPSCsevoked by stimulatingnucleusreticularis thalami and those occurring spontaneouslywere analyzed. During the first postnatalmonth, the decay time of spontaneousand evoked IPSCsbecameprogressivelyshorter,whereasthe rise-timeremainedconstant.We concludethat the fast kinetics of GABAergic IPSCs in mature rat thalamus could be achieved by changesin the expressionof GABA, receptor subunits.