Impact of S100B on local field potential patterns in anesthetized and kainic acid-induced seizure conditions in vivo.
S100B is a calcium-binding protein predominantly expressed in astrocytes. Previous studies using gene-manipulated animals have suggested that the protein has a role in synaptic plasticity and learning. In order to assess the physiological roles of the protein in active neural circuitry, we recorded spontaneous neural activities from various layers of the neocortex and hippocampus in urethane-anesthetized S100B knockout (KO) and wildtype (WT) control mice. Typical local field oscillation patterns including the slow (0.5-2 Hz) oscillations in the neocortex, theta (3-8 Hz) and sharp wave-associated ripple (120-180 Hz) oscillations in the hippocampus were observed in both genotypes. Comparisons of the frequency, power and peak amplitude have shown that these oscillatory patterns were virtually indistinguishable between WT and KO. When seizure was induced by intraperitoneal injection of kainic acid, a difference between WT and KO appeared in the CA1 radiatum local field potential pattern, where seizure events were characterized by prominent appearance of hyper-synchronous gamma band (30-80 Hz) activity. Although both genotypes developed seizures within 40 min, the gamma amplitude was significantly smaller during the development of seizures in KO mice. Our results suggest that deficiency of S100B does not have a profound impact on spontaneous neural activity in normal conditions. However, when neural activity was sufficiently raised, activation of S100B-related pathways may take effect, resulting in modulation of neural activities.
Sakatani
Seiichi
S
Hirase Research Unit, Neuronal Circuit Mechanisms Research Group, RIKEN Brain Science Institute, Wako-shi, 351-0198, Japan.
Seto-Ohshima
Akiko
A
Itohara
Shigeyoshi
S
Hirase
Hajime
H
D000818:Animals; D004569:Electroencephalography / Q000379:methods; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology*; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D007608:Kainic Acid; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009414:Nerve Growth Factors / Q000172:deficiency / Q000502:physiology*; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins / Q000172:deficiency / Q000502:physiology*; D012640:Seizures / Q000139:chemically induced / Q000503:physiopathology*; D013997:Time Factors
D005904:Glial Fibrillary Acidic Protein; D009414:Nerve Growth Factors; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; C579159:S100b protein, mouse; D007608:Kainic Acid