Critical roles of voltage-dependent sodium channels in the process of synaptogenesis during the postnatal cortical development of rats.
The developmental changes of the sodium channel and construction of synapse connection were studied in cerebral cortical pyramidal neurons of rats at different age groups. We used whole-cell patch-clamp recordings to characterize electrophysiological properties of cortical neurons at different age stages, including the sodium currents, APs evoked by depolarizing current and short-term plasticity of the eEPSCs. The result shows that the sodium currents undergo a hyperpolarizing shift in activation process and acceleration of activation and inactivation with age. The maximal sodium current also increased with maturation, and the evident difference appeared from P7-P11 (with the day of birth as P0) to P12-P15 group. The tendency of the sodium current density changes which exhibited the same properties as that of sodium current, showed the significant increases from P19-P21 to P >or= 22 group. The APs' parameters exhibited the age-dependent changes except the threshold, including the increase of the peak amplitude from P <or= 6 to P16-P18 groups, and the curtailment of duration and the time-to-peak with age. The amplitude of 1st eEPSC increased with maturation, and STP displays depression at all observed groups. In addition, although STP also exhibited depression in response to last three stimulations in P >or= 22 group, the 2nd response showed the tendency of facilitation compared with the younger age groups. Our results indicated that the cerebral cortical pyramidal neurons of rats are undergoing marked changes in the characteristics of their sodium channels with maturation, which play a critical role in synaptogenesis and construction of the neuronal network.
Wang
Ke
K
Department of Biological Science and Technology, School of Life Sciences, Sun Yat-sen (Zhongshan) University, 135 Xingang Xi Road, 510275, Guangzhou, Guangdong Province, People's Republic of China.
Cui
Jihong
J
Cai
Yijun
Y
Wang
Fang
F
Li
Yi
Y
Tao
Wucheng
W
Xiang
Hui
H
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D002454:Cell Differentiation; D002540:Cerebral Cortex / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism*; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D015640:Ion Channel Gating / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000502:physiology; D038081:Organogenesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D015222:Sodium Channels / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism*; D013997:Time Factors
D015222:Sodium Channels