- Email: [email protected]
Involvement of equilibrative and concentrative nucleoside transporters in hydrogen peroxide-induced thymidine incorporation into cultured astrocytes
S148
Abstracts
Expression of chondroitin 6-sulfotransferase 1 (C6ST1) is increased in cortical stub injury in wild type mice, but is not in OASIS knock out mice. These results suggest that OASIS may be involved in CSPG production through the transcription of C6ST1 in astrocytes. doi:10.1016/j.neures.2009.09.746
P2-c10 Environmental enrichment in juvenile period stimulates olig2 cells to self-renew and/or differentiate into astrocytes in mouse amygdala Kouko Tatsumi 1 , Hiroaki Okuda 1 , Aya Yamamoto 1 , Mariko Yamano 2 , Akio Wanaka 1 1
Nara Medical University, Nara, Japan; 2 Department of Comprehensive Rehabilitation, Faculty of Comprehensive Rehabilitation, Osaka Prefecture University, Osaka, Japan
Recent studies have demonstrated that enriched environment (EE) is beneficial in animal models of various pathological or psychiatric disorders. But the effect of EE on the amygdala, one of the major emotion-related structures in the central nervous system, remains largely unknown. In this study, we focused on the effects of EE on Olig2 cells in the adult murine amygdala. Our preliminary study showed that Olig2 cells co-expressed NG2 or PDGFR␣, indicating their progenitor-like properties, in the gray matter of the normal adult brain. In this genetic tracing study targeted on Olig2 locus, Olig2 cells in the amygdala showed two different lineages under the enriched condition; one is actively self-renewing and the other tends to differentiate into astrocytes. Taken together with previous behavioral studies, Olig2-lineage cells in the amygdala may contribute to beneficial aspects of EE such as anxiolytic effects. doi:10.1016/j.neures.2009.09.747
P2-c13 Involvement of equilibrative and concentrative nucleoside transporters in hydrogen peroxide-induced thymidine incorporation into cultured astrocytes Koh-ichi Tanaka 1,2,3 , Junichi Kitanaka 2 , Nobue Kitanaka 2 , Tomoaki Sato 3 , Takashige Nishikawa 3 , Motohiko Takemura 2 , Nobuyoshi Nishiyama 1 1 Div. Pharmacol, Dept. Pharm., Sch. Pharm., Hyogo Univ. Health Sci., Japan; 2 Dept. Pharmacol, Hyogo Col. Med., Japan; 3 Dept. Applied Pharmacol, Kagoshima Univ. Grad. Sch. Med. & Dent. Sci., Japan
Nucleoside transporters have been categorized into two groups. We examined the expression of equilibrative nucleoside transporters (ENT) and concentrative nucleoside transporters (CNT) mRNAs in cultured astrocytes by RT-PCR. Cultured astrocytes expressed ENT1, ENT2 and CNT2. Next, we examined the involvement of ENT and CNT in hydrogen peroxide (H2 O2 )induced thymidine incorporation into cultured astrocytes. Thymidine incorporation in the presence and absence of H2 O2 was suppressed partially by the applications of nitrobenzylthioinosine, dilazep and dipyridamole, ENT inhibitors or in the absence of extracellular Na+ . These findings indicate that astrocytes possess functional ENT and CNT, and incorporate thymidine through ENT and CNT in the presence and absence of H2 O2 . doi:10.1016/j.neures.2009.09.750
P2-c14 Glycine released during glial metabolic inhibition contributes to modulation of excitatory synaptic transmission in the hippocampus Mitsuo Tanabe, Yuko Yamamoto, Hideki Ono Lab. CNS Pharmacol., Grad. Sch. Pharm. Sci., Nagoya City University, Japan
P2-c11 Evoked currents in CA1 stratum lacunosum-moleculare (SLM) astrocyte by adjacent interneuron firings Kiyoshi Egawa 1 , Junko Yamada 2 , Tomonori Furukawa 1 , Atsuo Fukuda 1 1
Hamamatsu Univ. Sch. of Med., Japan;
2
Hirosaki Univ. Sch. of Med., Japan
To clarify glial responses to GABA spill-over in the neuronal networks, we performed dual whole-cell recording from interneuron-astrocyte pairs in SLM layer using GAD67-GFP knock in mice. The [Cl− ]i of astorcytes was adjusted to physiological condition (40 mM). Trains of interneuron firing induced inward currents in the adjacent astrocyte, which were completely blocked by BMI. GAT1 inhibitor increased the astrocytic inward currents and induced BMI-insensitive, GAT3 inhibitor-sensitive currents. Gap junction (GPJ) inhibitors reduced the inward currents by the distance dependent manner. Currents recorded from the pairs with longer distance were completely abolished by carbenoxolone. The results indicate that spill-over of GABA induces Cl− efflux from CA1 astorocyte via GABAA receptors accompanied by Cl− conductance between astrocytes through GPJs. Since GABAA conductance of postsynaptic neurons and GATs could take up Cl− from synaptic clefts, these astrocytic Cl− conductance might spatially buffer [Cl− ]o change and maintain GABAergic synapse transmission. doi:10.1016/j.neures.2009.09.748
We explored whether glycine participates in neuroprotective reduction of excitatory synaptic transmission during acute glial metabolic inhibition. Superfusion of the astrocyte specific metabolic inhibitor fluoroacetate (FAC) reduced the population spike (PS) and the field excitatory postsynaptic potentials (fEPSPs) elicited in the CA1 region of mouse hippocampal slices. Blockade of strychnine-sensitive glycine receptors largely attenuated the FAC-induced inhibition of PS but not that of fEPSPs, suggesting that glial metabolic inhibition elicits glycine release that then reduces excitatory transmission by lowering cellular excitability. Under blockade of glycine transporter 1 (GlyT1) by NFPS, the FAC-induced inhibition of PS was delayed and attenuated. Moreover, NFPS reversed the FAC-induced inhibition of PS in most experiments (5 of 8 slices). Together, glial metabolic inhibition releases glycine partly by reverse operation of glial GlyT1 to serve as a protective mechanism mediated via strychnine-sensitive glycine receptors. doi:10.1016/j.neures.2009.09.751
P2-c15 Reduced astrocytic IP3 -mediated Ca2+ signaling results in behavioral abnormality in mice Mika Tanaka 1 , Junichi Nakai 1,2 , Alexander Lebedinskiy 1 , Hiroshi Gomi 1,3 , Katsuhiko Mikoshiba 1 , Alexey Semyanov 1 , Shigeyoshi Itohara 1 1
P2-c12 Glial overexpression of amyloid precursor protein influences normal excitatory synaptic transmission Shutaro Katsurabayashi, Sachiko Nakano, Kotaro Takasaki, Kenichi Mishima, Katsunori Iwasaki, Michihiro Fujiwara Dept. Neuropharmacol, Fukuoka Univ., Fukuoka, Japan Amyloid precursor protein (APP) is an essential protein which produces -amyloid peptide (A). In the early stages of Alzheimer’s disease brain, overexpression of neuronal APP causes a secretion of soluble A, which accounts for synaptic depression and abnormal synaptogenesis before plaque formation. Although it is fact that APP is abundant in neurons, little is known whether functional APP is distributed in astrocyte as well. We found that overexpression of the Swedish mutant APP (APPsw) observed in the cultured cortical astrocytes and remarkably secreted A in Tg2576 mouse model that genetically overexpressed APPsw. Using autaptic cultures of normal hippocampal neurons on the micro islands of cortical astrocyte obtained from either wild-type or APPsw mutant, astrocytic APPsw overexpression depressed excitatory synaptic transmission. Our findings propose that in Alzheimer’s disease, soluble A secreted from the astrocytes disrupts naïve synaptic functions, resulting in a descent of synaptic plasticity. doi:10.1016/j.neures.2009.09.749
3
RIKEN BSI, Wako, Japan; 2 Saitama Univ., Brain. Sci. Inst., Saitama, Japan; Gunma Univ., Inst. Mol. Cell. Regulation, Maebashi, Japan
Although several in vitro and in situ studies have suggested that neuronal activity can be modulated by Ca2+ dependent release of gliotransmitters from astrocytes, the significance of astrocytic Ca2+ signaling in higher brain function is largely unknown. To address this issue, we generated an astrocyte-specific gene induction system to attenuate astrocytic Ca2+ signaling in vivo. We generated GLT-1-tTA transgenic mouse lines for astrocyte-specific expression of tTA, and TRE-IP3 sponge transgenic lines for inducible expression of IP3 absorbent. In [GLT-1-tTA, TRE-IP3 sponge] double transgenic mice, we observed that expression of IP3 sponge significantly attenuated spontaneous astrocytic Ca2+ oscillation in hippocampus. Subsequent behavioral analyses have revealed that spatial reference memory and fear memory were impaired in those mice. Our results first demonstrate that astrocytic Ca2+ signaling plays a role in learning and memory. doi:10.1016/j.neures.2009.09.752
Abstracts
Expression of chondroitin 6-sulfotransferase 1 (C6ST1) is increased in cortical stub injury in wild type mice, but is not in OASIS knock out mice. These results suggest that OASIS may be involved in CSPG production through the transcription of C6ST1 in astrocytes. doi:10.1016/j.neures.2009.09.746
P2-c10 Environmental enrichment in juvenile period stimulates olig2 cells to self-renew and/or differentiate into astrocytes in mouse amygdala Kouko Tatsumi 1 , Hiroaki Okuda 1 , Aya Yamamoto 1 , Mariko Yamano 2 , Akio Wanaka 1 1
Nara Medical University, Nara, Japan; 2 Department of Comprehensive Rehabilitation, Faculty of Comprehensive Rehabilitation, Osaka Prefecture University, Osaka, Japan
Recent studies have demonstrated that enriched environment (EE) is beneficial in animal models of various pathological or psychiatric disorders. But the effect of EE on the amygdala, one of the major emotion-related structures in the central nervous system, remains largely unknown. In this study, we focused on the effects of EE on Olig2 cells in the adult murine amygdala. Our preliminary study showed that Olig2 cells co-expressed NG2 or PDGFR␣, indicating their progenitor-like properties, in the gray matter of the normal adult brain. In this genetic tracing study targeted on Olig2 locus, Olig2 cells in the amygdala showed two different lineages under the enriched condition; one is actively self-renewing and the other tends to differentiate into astrocytes. Taken together with previous behavioral studies, Olig2-lineage cells in the amygdala may contribute to beneficial aspects of EE such as anxiolytic effects. doi:10.1016/j.neures.2009.09.747
P2-c13 Involvement of equilibrative and concentrative nucleoside transporters in hydrogen peroxide-induced thymidine incorporation into cultured astrocytes Koh-ichi Tanaka 1,2,3 , Junichi Kitanaka 2 , Nobue Kitanaka 2 , Tomoaki Sato 3 , Takashige Nishikawa 3 , Motohiko Takemura 2 , Nobuyoshi Nishiyama 1 1 Div. Pharmacol, Dept. Pharm., Sch. Pharm., Hyogo Univ. Health Sci., Japan; 2 Dept. Pharmacol, Hyogo Col. Med., Japan; 3 Dept. Applied Pharmacol, Kagoshima Univ. Grad. Sch. Med. & Dent. Sci., Japan
Nucleoside transporters have been categorized into two groups. We examined the expression of equilibrative nucleoside transporters (ENT) and concentrative nucleoside transporters (CNT) mRNAs in cultured astrocytes by RT-PCR. Cultured astrocytes expressed ENT1, ENT2 and CNT2. Next, we examined the involvement of ENT and CNT in hydrogen peroxide (H2 O2 )induced thymidine incorporation into cultured astrocytes. Thymidine incorporation in the presence and absence of H2 O2 was suppressed partially by the applications of nitrobenzylthioinosine, dilazep and dipyridamole, ENT inhibitors or in the absence of extracellular Na+ . These findings indicate that astrocytes possess functional ENT and CNT, and incorporate thymidine through ENT and CNT in the presence and absence of H2 O2 . doi:10.1016/j.neures.2009.09.750
P2-c14 Glycine released during glial metabolic inhibition contributes to modulation of excitatory synaptic transmission in the hippocampus Mitsuo Tanabe, Yuko Yamamoto, Hideki Ono Lab. CNS Pharmacol., Grad. Sch. Pharm. Sci., Nagoya City University, Japan
P2-c11 Evoked currents in CA1 stratum lacunosum-moleculare (SLM) astrocyte by adjacent interneuron firings Kiyoshi Egawa 1 , Junko Yamada 2 , Tomonori Furukawa 1 , Atsuo Fukuda 1 1
Hamamatsu Univ. Sch. of Med., Japan;
2
Hirosaki Univ. Sch. of Med., Japan
To clarify glial responses to GABA spill-over in the neuronal networks, we performed dual whole-cell recording from interneuron-astrocyte pairs in SLM layer using GAD67-GFP knock in mice. The [Cl− ]i of astorcytes was adjusted to physiological condition (40 mM). Trains of interneuron firing induced inward currents in the adjacent astrocyte, which were completely blocked by BMI. GAT1 inhibitor increased the astrocytic inward currents and induced BMI-insensitive, GAT3 inhibitor-sensitive currents. Gap junction (GPJ) inhibitors reduced the inward currents by the distance dependent manner. Currents recorded from the pairs with longer distance were completely abolished by carbenoxolone. The results indicate that spill-over of GABA induces Cl− efflux from CA1 astorocyte via GABAA receptors accompanied by Cl− conductance between astrocytes through GPJs. Since GABAA conductance of postsynaptic neurons and GATs could take up Cl− from synaptic clefts, these astrocytic Cl− conductance might spatially buffer [Cl− ]o change and maintain GABAergic synapse transmission. doi:10.1016/j.neures.2009.09.748
We explored whether glycine participates in neuroprotective reduction of excitatory synaptic transmission during acute glial metabolic inhibition. Superfusion of the astrocyte specific metabolic inhibitor fluoroacetate (FAC) reduced the population spike (PS) and the field excitatory postsynaptic potentials (fEPSPs) elicited in the CA1 region of mouse hippocampal slices. Blockade of strychnine-sensitive glycine receptors largely attenuated the FAC-induced inhibition of PS but not that of fEPSPs, suggesting that glial metabolic inhibition elicits glycine release that then reduces excitatory transmission by lowering cellular excitability. Under blockade of glycine transporter 1 (GlyT1) by NFPS, the FAC-induced inhibition of PS was delayed and attenuated. Moreover, NFPS reversed the FAC-induced inhibition of PS in most experiments (5 of 8 slices). Together, glial metabolic inhibition releases glycine partly by reverse operation of glial GlyT1 to serve as a protective mechanism mediated via strychnine-sensitive glycine receptors. doi:10.1016/j.neures.2009.09.751
P2-c15 Reduced astrocytic IP3 -mediated Ca2+ signaling results in behavioral abnormality in mice Mika Tanaka 1 , Junichi Nakai 1,2 , Alexander Lebedinskiy 1 , Hiroshi Gomi 1,3 , Katsuhiko Mikoshiba 1 , Alexey Semyanov 1 , Shigeyoshi Itohara 1 1
P2-c12 Glial overexpression of amyloid precursor protein influences normal excitatory synaptic transmission Shutaro Katsurabayashi, Sachiko Nakano, Kotaro Takasaki, Kenichi Mishima, Katsunori Iwasaki, Michihiro Fujiwara Dept. Neuropharmacol, Fukuoka Univ., Fukuoka, Japan Amyloid precursor protein (APP) is an essential protein which produces -amyloid peptide (A). In the early stages of Alzheimer’s disease brain, overexpression of neuronal APP causes a secretion of soluble A, which accounts for synaptic depression and abnormal synaptogenesis before plaque formation. Although it is fact that APP is abundant in neurons, little is known whether functional APP is distributed in astrocyte as well. We found that overexpression of the Swedish mutant APP (APPsw) observed in the cultured cortical astrocytes and remarkably secreted A in Tg2576 mouse model that genetically overexpressed APPsw. Using autaptic cultures of normal hippocampal neurons on the micro islands of cortical astrocyte obtained from either wild-type or APPsw mutant, astrocytic APPsw overexpression depressed excitatory synaptic transmission. Our findings propose that in Alzheimer’s disease, soluble A secreted from the astrocytes disrupts naïve synaptic functions, resulting in a descent of synaptic plasticity. doi:10.1016/j.neures.2009.09.749
3
RIKEN BSI, Wako, Japan; 2 Saitama Univ., Brain. Sci. Inst., Saitama, Japan; Gunma Univ., Inst. Mol. Cell. Regulation, Maebashi, Japan
Although several in vitro and in situ studies have suggested that neuronal activity can be modulated by Ca2+ dependent release of gliotransmitters from astrocytes, the significance of astrocytic Ca2+ signaling in higher brain function is largely unknown. To address this issue, we generated an astrocyte-specific gene induction system to attenuate astrocytic Ca2+ signaling in vivo. We generated GLT-1-tTA transgenic mouse lines for astrocyte-specific expression of tTA, and TRE-IP3 sponge transgenic lines for inducible expression of IP3 absorbent. In [GLT-1-tTA, TRE-IP3 sponge] double transgenic mice, we observed that expression of IP3 sponge significantly attenuated spontaneous astrocytic Ca2+ oscillation in hippocampus. Subsequent behavioral analyses have revealed that spatial reference memory and fear memory were impaired in those mice. Our results first demonstrate that astrocytic Ca2+ signaling plays a role in learning and memory. doi:10.1016/j.neures.2009.09.752