Henze D A, Card J P, Barrionuevo G, Ben-Ari Y
Department of Neuroscience, University of Pittsburgh, Pennsylvania 15260, USA.
J Neurophysiol. 1997 Mar;77(3):1075-86. doi: 10.1152/jn.1997.77.3.1075.
Neonatal (P0) gamma-irradiation was used to lesion selectively the mossy fiber (MF) synaptic input to CA3 pyramidal cells. This lesion caused a > 85% reduction in the MF input as determined by quantitative assessment of the number of dynorphin immunoreactive MF boutons. The gamma-irradiation lesion caused a reduction in the mean number of miniature excitatory postsynaptic currents (mEPSCs) recorded from CA3 pyramidal cells (2,292 vs. 1,429/3-min period; n = 10). The lesion also caused a reduction in the mean mEPSC peak amplitude from 19.1 +/- 0.45 to 14.6 +/- 0.49 pA (mean +/- SE; peak conductance 238.8 +/- 5.6 to 182.0 +/- 6.1 pS). Similarly, there was a reduction in the mean 10-85% rise time from 1.72 +/- 0.02 ms to 1.42 +/- 0.04 ms. The effects of the gamma-irradiation on both mEPSC amplitude and 10-85% rise time were significant at P < 0.002 and P < 0.005 (2-tailed Kolmogorov-Smirnov test). Based on the selectively of the gamma-irradiation, MF and non-MF mEPSC amplitude and 10-85% rise-time distributions were calculated. Both the amplitude and 10-85% rise-time distributions showed extensive overlap between the MF and non-MF mediated mEPSCs. The MF mEPSC distributions had a mean peak amplitude of 24.6 pA (307.5 pS) and a mean 10-85% rise time of 2.16 ms. THe non-MF mEPSC distributions had a mean peak amplitude of 12.2 pA (152.5 pS) and 10-85% rise time of 1.26 ms. The modes of the amplitude distributions were the same at 5 pA (62 pS). The MF and non-MF mEPSC amplitude and 10-85% rise-time distributions were significantly different at P << 0.001 (1-tailed, large sample Kolmogorov-Smirnov test). The data demonstrate that the removal of the MF synaptic input to CA3 pyramidal cells leads to the absence of the large amplitude mEPSCs that are present in control recordings.
新生期（P0）γ射线照射被用于选择性损伤苔藓纤维（MF）至CA3锥体细胞的突触输入。通过对强啡肽免疫反应性MF终扣数量进行定量评估确定，这种损伤导致MF输入减少超过85%。γ射线照射损伤使从CA3锥体细胞记录到的微小兴奋性突触后电流（mEPSC）的平均数量减少（3分钟期间：2292次对1429次；n = 10）。该损伤还使mEPSC的平均峰值幅度从19.1±0.45 pA降至14.6±0.49 pA（平均值±标准误；峰值电导从238.8±5.6 pS降至182.0±6.1 pS）。同样，平均10 - 85%上升时间从1.72±0.02毫秒降至1.42±0.04毫秒。γ射线照射对mEPSC幅度和10 - 85%上升时间的影响在P < 0.002和P < 0.005时具有显著性（双侧柯尔莫哥洛夫-斯米尔诺夫检验）。基于γ射线照射的选择性，计算了MF和非MF的mEPSC幅度以及10 - 85%上升时间分布。幅度和10 - 85%上升时间分布均显示MF介导的和非MF介导的mEPSC之间有广泛重叠。MF的mEPSC分布平均峰值幅度为24.6 pA（307.5 pS），平均10 - 85%上升时间为2.16毫秒。非MF的mEPSC分布平均峰值幅度为12.2 pA（152.5 pS），10 - 85%上升时间为1.26毫秒。幅度分布的众数相同，均为5 pA（62 pS）。MF和非MF的mEPSC幅度以及10 - 85%上升时间分布在P << 0.001时具有显著差异（单侧，大样本柯尔莫哥洛夫-斯米尔诺夫检验）。数据表明，去除MF至CA3锥体细胞的突触输入会导致对照记录中存在的大幅度mEPSC缺失。
