The Journal of Neuroscience, October 22, 2008, 28(43):10928-10936; doi:10.1523/JNEUROSCI.3693-08.2008
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Cellular/Molecular
Neural-Activity-Dependent Release of S100B from Astrocytes Enhances Kainate-Induced Gamma Oscillations In Vivo
Seiichi Sakatani,1
Akiko Seto-Ohshima,2
Yoshiaki Shinohara,1
Yasuhiko Yamamoto,3
Hiroshi Yamamoto,3
Shigeyoshi Itohara,2 and
Hajime Hirase1
1Hirase Research Unit, Neuronal Circuit Mechanisms Research Group, and 2Laboratory for Behavioral Genetics, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan, 3Department of Biochemistry and Molecular Vascular Biology, Kanazawa University Graduate School of Medical Science, Kanazawa 920-0864, Japan
Correspondence should be addressed to either of the following at the same address: Seiichi Sakatani or Hajime Hirase, RIKEN Brain Science Institute, Neuronal Circuit Mechanisms Research Group, Wako-shi, 351-0198, Japan. Email: sakatani{at}brain.riken.jp or Email: hirase{at}brain.riken.jp
S100B is the principal calcium-binding protein of astrocytes and known to be secreted to extracellular space. Although secreted S100B has been reported to promote neurite extension and cell survival via its receptor [receptor for advanced glycation end products (RAGE)], effects of extracellular S100B on neural activity have been mostly unexplored. Here, we demonstrate that secreted S100B enhances kainate-induced gamma oscillations. Local infusion of S100B in S100B(–/–) mice enhanced hippocampal kainate-induced gamma oscillations in vivo. In a complementary set of experiments, local application of anti-S100B antibody in wild-type mice attenuated the gamma oscillations. Both results indicate that the presence of extracellular S100B enhances the kainate-induced gamma oscillations. In acutely isolated hippocampal slices, kainate application increased S100B secretion in a neural-activity-dependent manner. Further pharmacological experiments revealed that S100B secretion was critically dependent on presynaptic release of neurotransmitter and activation of metabotropic glutamate receptor 3. Moreover, the kainate-induced gamma oscillations were attenuated by the genetic deletion or antibody blockade of RAGE in vivo. These results suggest RAGE activation by S100B enhances the gamma oscillations. Together, we propose a novel pathway of neuron–glia communications—astrocytic release of S100B modulates neural network activity through RAGE activation.
Key words: glia; hippocampus; mGluR3; local field potential; seizure; neuron–glia interactions
Received Aug. 4, 2008;
accepted Sept. 13, 2008.
Correspondence should be addressed to either of the following at the same address: Seiichi Sakatani or Hajime Hirase, RIKEN Brain Science Institute, Neuronal Circuit Mechanisms Research Group, Wako-shi, 351-0198, Japan. Email: sakatani{at}brain.riken.jp or Email: hirase{at}brain.riken.jp