Modification of hippocampal excitability in brain slices pretreated with a low nanomolar concentration of Zn2+.
Synaptic Zn2+ homeostasis may be changed during brain slice preparation. However, much less attention has been paid to Zn2+ in artificial cerebrospinal fluid (ACSF) used for slice experiments than has been paid to Ca2+ . The present study assesses addition of Zn2+ to ACSF, focused on hippocampal excitability after acute brain slice preparation. When the static levels of intracellular Zn2+ and Ca2+ were compared between brain slices prepared with conventional ACSF without Zn2+ and those pretreated with ACSF containing 20 nM ZnCl2 for 1 hr, both levels were almost the same. On the other hand, intracellular Ca2+ levels were significantly increased in the stratum lucidum of the control brain slices after stimulation with high K+, although the increase was significantly suppressed by the pretreatment with ACSF containing Zn2+, suggesting that neuronal excitation is enhanced in brain slices prepared with ACSF without Zn2+. The increase in extracellular Zn2+ level, an index of glutamate release, after stimulation with high K+ was also significantly suppressed by pretreatment with ACSF containing Zn2+. When mossy fiber excitation was assessed in brain slices with FM4-64, an indicator of presynaptic activity, attenuation of FM 4-64 fluorescence based on presynaptic activity was suppressed in the stratum lucidum of brain slices pretreated with ACSF containing Zn2+. The present study indicates that hippocampal excitability is enhanced in brain slices prepared with ACSF without Zn2+. It is likely that a low nanomolar concentration of Zn2+ is necessary for ACSF.
Department of Neurophysiology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
Atsushi
A
Takeda
Department of Neurophysiology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
Yukina
Y
Shakushi
Department of Neurophysiology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
Haruna
H
Tamano
D000818:Animals; D003470:Culture Media / Q000737:chemistry*; D006624:Hippocampus / Q000378:metabolism*; D008297:Male; D018613:Microscopy, Confocal; D009924:Organ Culture Techniques / Q000379:methods*; D051381:Rats; D017208:Rats, Wistar; D009435:Synaptic Transmission / Q000502:physiology; D015032:Zinc / Q000378:metabolism*
D003470:Culture Media; D015032:Zinc
Zn2+; artificial cerebrospinal fluid; brain slice; hippocampus