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α2-Adrenoceptor activation reduces GABAergic synaptic transmission in the developing mouse cerebellar cortex
Abstracts / Neuroscience Research 58S (2007) S1–S244
P1-a14 Enhancement by PAR-1 activation of glutamatergic excitatory transmission in adult rat substantia gelatinosa neurons Tsugumi Fujita, Tao Liu, Terumasa Nakatsuka, Eiichi Kumamoto Department of Physiology, Faculty of Medicine, Saga University, Saga, Japan We have previously reported that proteinase-activated receptor-1 (PAR-1) agonist peptide SFLLRN reversibly increases the frequency of spontaneous EPSC (sEPSC) without a change in the amplitude in substantia gelatinosa (SG) neurons. In the present study, we further examined the PAR-1 agonist mediated enhancement of excitatory transmission by applying the whole-cell patch-clamp technique to SG neurons in adult rat spinal cord slices. The presynaptic effect of SFLLRN was resistant to tetrodotoxin, and was not seen in the presence of PAR-1 antagonist peptide YFLLRNP. Peptide TFLLR, which is more selective to PAR-1 than SFLLRN, also increased sEPSC frequency without a change in its amplitude; this action was dose-dependent. Similar facilitatory effect was seen by endogenous PAR-1 agonist proteinase thrombin. These results indicate that PAR-1 activation in nerve terminals enhances the spontaneous release of L-glutamate onto SG neurons. It remains to be examined how PAR-1 activation results in enhancing L-glutamate release.
P1-a15 Dendritic dimensions of cortical nonpyramidal cells Yoshiyuki Kubota 1 , Fuyuki Karube 1 , Masaki Nomura 3 , Toshio Aoyagi 3 , Atsushi Mochizuki 2 , Yasuo Kawaguchi 1 1 Div. Cerebral Circuitry, NIPS, Okazaki, Japan; 2 Div. Theoretical Biology, NIBB, Okazaki, Japan; 3 Kyoto University Grad. Sch. Informatics, Kyoto, Japan Cortical nonpyramidal cells (NP) are composed of several dendritic types different in branching patterns. In addition, local morphologies are also important for the input interaction and transmittance to somata. We measured dendritic perimeter, cross sectional area and synapse density along dendrites of each NP subtype: a FS basket cell, double bouquet cell, Martinotti cell, and large basket cell. Many portions of the dendrites from each NP subtype were reconstructed three-dimensionally from serial ultra-thin sections. The synaptic densities on their dendrites were almost uniform from proximal to distal dendrites, but different between subtypes. At branching, a parent cross sectional area was almost equal to the sum of those of two daughter branches. Input conductance estimation using the circumference and cross sectional areas suggested impedance matching between parent and daughter branches at the node according to Rall’s model. Importance of the impedance matching is studied by theoretical analysis. Research funds: KAKENHI
S73
P1-bØ1 Firing pattern dependent specificity of cortical feedforward subnetworks Takeshi Otsuka, Mieko Morishima, Yasuo Kawaguchi Div. Cerebral Circuitry & Structure, NIPS, Okazaki, Japan Previously, we reported that L5 pyramidal cells could be divided into three types by their firing patterns and were correlated with their subcortical target. Here, we examined whether these types of cells form specific functional subnetworks. Whole cell recordings were obtained from rat frontal cortical slices. First, we characterized physiological properties of L2/3 pyramidal cells. Like those of L5 cells, firing patterns of L2/3 cells were divided into three types showing no spike frequency adaptation or no frequency adaptation with burst at the initial phase or strong frequency adaptation during current injections. Dual recordings of L5 and 2/3 cells revealed all types of L5 cells received inputs from L2/3 cells fired with no spike adaptation. However, L2/3 cells fired with strong spike adaptation or burst made synapses with similar types of L5 cells, respectively. We also examined if these types of L5 cells share common inputs from L2/3 cells using dual recordings and single cell stimulation. Our results suggest networks from L2/3 to 5 have specificity depending on firing patterns. Research funds: KAKENHI (18700328)
P1-bØ2 Evidence of nigral inhibitory inputs to GABAergic neurons in mouse superior colliculus Kaoru Isa 1,2 , Katsuyuki Kaneda 1,3 , Yuchio Yanagawa 4 , Kunihiko Obata 5 , Tadashi Isa 1,2,3 1 Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Japan; 2 CREST JST, Japan; 3 Grad. University Adv. Stu., Okazaki, Japan; 4 Gunma University Grad. Sch. Med., Maebashi, Japan; 5 RIKEN, BSI, Wako, Japan The existence of direct inhibitory inputs from the substantia nigra pars reticulata (SNr), was examined in GABAergic neurons in the intermediate gray layer (SGI) of the superior colliculus (SC). For this purpose, we performed tract-tracing studies and whole-cell patch-clamp recordings using GAD67-GFP knock-in mice. Confocal fluorescence microscopic analysis revealed that after BDA injection into the SNr anterogradely labeled fibers from the SNr made synaptic contacts on GFP-positive SGI neurons. Voltage-clamp recordings showed that electrical stimulation of areas just ventral to the SC, where fibers from the SNr are located, evoked IPSCs in GFP-positive neurons. The IPSCs were monosynaptic and sensitive to a GABAA receptor antagonist. These results indicated that GABAergic SGI neurons receive nigral inibitory inputs and suggest that the SNr may not merely modulate the balance of excitation and inhibition in the SC local circuit. Research funds: KAKENHI 18200027, 18021039, HFSP, CREST
P1-a16 Differential involvement of GABAA IPSPs in inter-
P1-bØ3 ␣2 -Adrenoceptor activation reduces GABAergic synap-
Mitsuru Saito, Hajime Sato, Hiroki Toyoda, Youngnam Kang Department Neuroscience & Oral Physiology, Osaka University Graduate School of Dentistry, Osaka, Japan
Moritoshi Hirono, Wataru Matsunaga, Kunihiko Obata Neuronal Circuit Mechanisms Research Group, BSI, RIKEN, Wako, Japan
In comparison with the barrel cortex, the primary gustatory area in the insular cortex is thought to have much less distinct functional columns. We examined the differences in the spatiotemporal pattern of excitation spread between the barrel and insular cortices, using voltage-sensitive dye imaging. The excitation evoked by stimulation of layer IV of the barrel cortex spread upwardly into layer II/III, where the excitation spread horizontally into neighboring columns partially, leaving the layer V/VI unexcited. By contrast, the excitation in layer IV of the insular cortex spread bi-directionally into layers II/III and V/VI, while the horizontal spread in layer II/III was much less prominent. Bicuculline application markedly enlarged the extent of horizontal spread in layer II/III of the barrel cortex, but not the case for the insular cortex. These results suggest that the involvement of GABAA receptors in the lateral inhibition in layers II/III is much more prominent in the barrel cortex than in the insular cortex.
Our previous study has demonstrated that a selective ␣2 -adrenoceptor agonist clonidine has a partial inhibitory effect on spontaneous IPSCs (sIPSCs) in mouse cerebellar Purkinje cells (PCs). Here, we found that the inhibitory effect of clonidine on sIPSCs was developmentally enhanced. Clonidine greatly reduced the frequency of spontaneous action potential (AP) in the molecular layer interneurons (MLIs), while the intensive attenuation was not age-dependently. To address the discrepancy between these inhibitory effects, we examined sIPSCs in PCs and AP in MLIs developmentally. During early postnatal days (
columnar communication in the barrel and insular cortices
tic transmission in the developing mouse cerebellar cortex
Research funds: KAKENHI (16700344)
P1-a14 Enhancement by PAR-1 activation of glutamatergic excitatory transmission in adult rat substantia gelatinosa neurons Tsugumi Fujita, Tao Liu, Terumasa Nakatsuka, Eiichi Kumamoto Department of Physiology, Faculty of Medicine, Saga University, Saga, Japan We have previously reported that proteinase-activated receptor-1 (PAR-1) agonist peptide SFLLRN reversibly increases the frequency of spontaneous EPSC (sEPSC) without a change in the amplitude in substantia gelatinosa (SG) neurons. In the present study, we further examined the PAR-1 agonist mediated enhancement of excitatory transmission by applying the whole-cell patch-clamp technique to SG neurons in adult rat spinal cord slices. The presynaptic effect of SFLLRN was resistant to tetrodotoxin, and was not seen in the presence of PAR-1 antagonist peptide YFLLRNP. Peptide TFLLR, which is more selective to PAR-1 than SFLLRN, also increased sEPSC frequency without a change in its amplitude; this action was dose-dependent. Similar facilitatory effect was seen by endogenous PAR-1 agonist proteinase thrombin. These results indicate that PAR-1 activation in nerve terminals enhances the spontaneous release of L-glutamate onto SG neurons. It remains to be examined how PAR-1 activation results in enhancing L-glutamate release.
P1-a15 Dendritic dimensions of cortical nonpyramidal cells Yoshiyuki Kubota 1 , Fuyuki Karube 1 , Masaki Nomura 3 , Toshio Aoyagi 3 , Atsushi Mochizuki 2 , Yasuo Kawaguchi 1 1 Div. Cerebral Circuitry, NIPS, Okazaki, Japan; 2 Div. Theoretical Biology, NIBB, Okazaki, Japan; 3 Kyoto University Grad. Sch. Informatics, Kyoto, Japan Cortical nonpyramidal cells (NP) are composed of several dendritic types different in branching patterns. In addition, local morphologies are also important for the input interaction and transmittance to somata. We measured dendritic perimeter, cross sectional area and synapse density along dendrites of each NP subtype: a FS basket cell, double bouquet cell, Martinotti cell, and large basket cell. Many portions of the dendrites from each NP subtype were reconstructed three-dimensionally from serial ultra-thin sections. The synaptic densities on their dendrites were almost uniform from proximal to distal dendrites, but different between subtypes. At branching, a parent cross sectional area was almost equal to the sum of those of two daughter branches. Input conductance estimation using the circumference and cross sectional areas suggested impedance matching between parent and daughter branches at the node according to Rall’s model. Importance of the impedance matching is studied by theoretical analysis. Research funds: KAKENHI
S73
P1-bØ1 Firing pattern dependent specificity of cortical feedforward subnetworks Takeshi Otsuka, Mieko Morishima, Yasuo Kawaguchi Div. Cerebral Circuitry & Structure, NIPS, Okazaki, Japan Previously, we reported that L5 pyramidal cells could be divided into three types by their firing patterns and were correlated with their subcortical target. Here, we examined whether these types of cells form specific functional subnetworks. Whole cell recordings were obtained from rat frontal cortical slices. First, we characterized physiological properties of L2/3 pyramidal cells. Like those of L5 cells, firing patterns of L2/3 cells were divided into three types showing no spike frequency adaptation or no frequency adaptation with burst at the initial phase or strong frequency adaptation during current injections. Dual recordings of L5 and 2/3 cells revealed all types of L5 cells received inputs from L2/3 cells fired with no spike adaptation. However, L2/3 cells fired with strong spike adaptation or burst made synapses with similar types of L5 cells, respectively. We also examined if these types of L5 cells share common inputs from L2/3 cells using dual recordings and single cell stimulation. Our results suggest networks from L2/3 to 5 have specificity depending on firing patterns. Research funds: KAKENHI (18700328)
P1-bØ2 Evidence of nigral inhibitory inputs to GABAergic neurons in mouse superior colliculus Kaoru Isa 1,2 , Katsuyuki Kaneda 1,3 , Yuchio Yanagawa 4 , Kunihiko Obata 5 , Tadashi Isa 1,2,3 1 Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Japan; 2 CREST JST, Japan; 3 Grad. University Adv. Stu., Okazaki, Japan; 4 Gunma University Grad. Sch. Med., Maebashi, Japan; 5 RIKEN, BSI, Wako, Japan The existence of direct inhibitory inputs from the substantia nigra pars reticulata (SNr), was examined in GABAergic neurons in the intermediate gray layer (SGI) of the superior colliculus (SC). For this purpose, we performed tract-tracing studies and whole-cell patch-clamp recordings using GAD67-GFP knock-in mice. Confocal fluorescence microscopic analysis revealed that after BDA injection into the SNr anterogradely labeled fibers from the SNr made synaptic contacts on GFP-positive SGI neurons. Voltage-clamp recordings showed that electrical stimulation of areas just ventral to the SC, where fibers from the SNr are located, evoked IPSCs in GFP-positive neurons. The IPSCs were monosynaptic and sensitive to a GABAA receptor antagonist. These results indicated that GABAergic SGI neurons receive nigral inibitory inputs and suggest that the SNr may not merely modulate the balance of excitation and inhibition in the SC local circuit. Research funds: KAKENHI 18200027, 18021039, HFSP, CREST
P1-a16 Differential involvement of GABAA IPSPs in inter-
P1-bØ3 ␣2 -Adrenoceptor activation reduces GABAergic synap-
Mitsuru Saito, Hajime Sato, Hiroki Toyoda, Youngnam Kang Department Neuroscience & Oral Physiology, Osaka University Graduate School of Dentistry, Osaka, Japan
Moritoshi Hirono, Wataru Matsunaga, Kunihiko Obata Neuronal Circuit Mechanisms Research Group, BSI, RIKEN, Wako, Japan
In comparison with the barrel cortex, the primary gustatory area in the insular cortex is thought to have much less distinct functional columns. We examined the differences in the spatiotemporal pattern of excitation spread between the barrel and insular cortices, using voltage-sensitive dye imaging. The excitation evoked by stimulation of layer IV of the barrel cortex spread upwardly into layer II/III, where the excitation spread horizontally into neighboring columns partially, leaving the layer V/VI unexcited. By contrast, the excitation in layer IV of the insular cortex spread bi-directionally into layers II/III and V/VI, while the horizontal spread in layer II/III was much less prominent. Bicuculline application markedly enlarged the extent of horizontal spread in layer II/III of the barrel cortex, but not the case for the insular cortex. These results suggest that the involvement of GABAA receptors in the lateral inhibition in layers II/III is much more prominent in the barrel cortex than in the insular cortex.
Our previous study has demonstrated that a selective ␣2 -adrenoceptor agonist clonidine has a partial inhibitory effect on spontaneous IPSCs (sIPSCs) in mouse cerebellar Purkinje cells (PCs). Here, we found that the inhibitory effect of clonidine on sIPSCs was developmentally enhanced. Clonidine greatly reduced the frequency of spontaneous action potential (AP) in the molecular layer interneurons (MLIs), while the intensive attenuation was not age-dependently. To address the discrepancy between these inhibitory effects, we examined sIPSCs in PCs and AP in MLIs developmentally. During early postnatal days (
columnar communication in the barrel and insular cortices
tic transmission in the developing mouse cerebellar cortex
Research funds: KAKENHI (16700344)