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为了探索大鼠海马CA1区锥体神经元电压门控性Na+通道发育的关键期,本研究采用膜片钳技术,分别对急性分离的出生后0周、1周、2周、3周、4周的大鼠海马CA1区锥体神经元进行全细胞记录。结果显示,随着大鼠出生后周龄的增大,Na+通道的最大电流密度逐渐增大,出生后1~4周相对于出生后0周的最大电流密度的增幅分别为(42.76±4.91)%、(146.80±7.63)%、(208.79±5.28)%、(253.72±5.74)%(n=10,P<0.05),出生后1周与2周之间的增幅最为显著;Na+通道的稳态激活曲线向左移动,出生后0~2周的半数激活电压逐渐减小,分别为39.06±0.65、43.41±0.52、48.29±0.45(mV,n=10,P<0.05),出生后2~4周的半数激活电压变化不大,出生后0~4周的斜率因子没有显著变化;Na+通道的稳态失活曲线及半数失活电压没有显著变化,但出生后1~2周斜率因子减小,分别为5.77±0.56、4.42±0.43(n=10,P<0.05),出生后0~1周、2~4周之间的斜率因子没有明显变化;Na+通道失活后恢复曲线左移,出生后1~3周的恢复时间常数逐渐减小,分别为8.30±0.24、7.15±0.21、6.18±0.25(ms,n=10,P<0.05),而出生后0~1周、3~4周之间没有明显变化;随着出生后的发育,海马CA1区锥体神经元动作电位发生变化,超射值与最大上升速率增大,阈值降低,与Na+电流的变化一致。结果提示,出生后1~2周可能是电压门控性Na+通道发育的关键期,此期间Na+通道分布显著增加,激活曲线左移,失活速度变快,失活后恢复的时间缩短。
In order to explore the critical period of the development of voltage-gated Na + channels in pyramidal neurons of hippocampal CA1 region in rats, patch clamp technique was used in this study to evaluate the effects of acutely isolated 0, 1, 2, 3, 4 Week rat hippocampal CA1 pyramidal neurons were recorded whole-cell. The results showed that the maximal current density of Na + channel increased with the increase of the age of the rats, the maximum current densities of Na ~ + channels at 1 ~ 4 weeks after birth were (42.76 ± 4.91) %, (146.80 ± 7.63)%, (208.79 ± 5.28)%, (253.72 ± 5.74)% (n = 10, P <0.05) respectively. State activation curves shifted to the left. The half activation voltages at 0 ~ 2 weeks after birth decreased gradually, which were 39.06 ± 0.65, 43.41 ± 0.52 and 48.29 ± 0.45 (mV, n = 10, P <0.05) The half-activation voltage did not change much at 4 weeks, and there was no significant change at 0 ~ 4 weeks after birth. The steady state inactivation curve and half-inactivation voltage of Na + channel did not change significantly, but the slope factor decreased by 1 ~ 2 weeks Were 5.77 ± 0.56 and 4.42 ± 0.43 respectively (n = 10, P <0.05). There was no significant change in the slope factor between 0 and 1 week after birth and between 2 and 4 weeks. The recovery curve of Na + channel was shifted to the left , The recovery time constant of 1 ~ 3 weeks after birth decreased gradually, which were 8.30 ± 0.24, 7.15 ± 0.21 and 6.18 ± 0.25 respectively (ms, n = 10, P <0.05) No significant change between the 4 weeks; with the development after birth, the sea CA1 pyramidal neuron action potential is changed, overshoot is increased to the maximum rate of rise, reducing the threshold value, consistent with the change in Na + currents. The results suggest that 1 ~ 2 weeks after birth may be the key period for the development of voltage-gated Na + channels. During this period, the distribution of Na + channels increased significantly, the activation curve shifted to the left, the inactivation speed became faster, and the recovery time shortened after inactivation.