海马CA1和CA3区锥体细胞胞体上GABA能突触数量的差异(英文)

脑缺血再灌流导致海马CA1锥体细胞溃变而CA3神经元依然存活，这种选择性损伤的机制尚不清楚。两区间抑制性神经成分的差异可能是原因之一。本文用免疫细胞化学方法研究了上述假设的形态基础。在光镜下，CA1和CA3区每个锥体细胞环胞体的GABA阳性终末数分别是7.02±2.06和10.10±3.02（P＜0.001），每单位膜长度上的阳性终末数CA1也较CA3有意义的少。电镜下，GABA能终末与锥体细胞胞体形成对称性突触，CA1和CA3区锥体细胞的环胞体GABA阳性突触数分别是6.36±1.59和10.68±2.28（P＜0.01）。胞体膜被GABA能突触所覆盖的面分比也有显著差异（CA3=13.9±3.36％，CA1=10.9±5.06％，P＜0.001）。结果表明CA1神经元胞体较CA3神经元受到较少的GABA能支配。此点可能在脑缺血后CA1细胞较CA3细胞易损害机制中发挥作用。

QUANTITATIVE DIFFERENCE OF GABAERGIC SYNAPSES ON SOMATA OF PYRAMIDAL NEURONS IN THE CAI AND CA3 REGION OF RAT DORSAL HIPPOCAMPUS

CA1 pyramidal neurons degenerate after transient cerebral ischenda while CA3 neurons remain intact. The difference in inhibitory components between these two regions may play a role in this selective vulherability. The present study attempted to evaluate the morphological basis for the above hypothesis. Under light microscopy, the number of GABA-positive puncta around each soma of pyramidal neurons was 7. 02±2. 06 in CA1 and 10. 10±3. 02 in CA3 (P<0. 001 ). The number of puncta per 10 μm membrane was also significantly lower in CA1. Electron microscopic observation revealed that these GABA-positive puncta formed symmetrical synapses. The number of GABAergic synapses per somatic circumference in CA1 was smaller than that in CA3. The number of GABAergic synapses per 10 μm membrane was also significantly lower in CAI. The percentage of somatic membrane covered by GABAergic synapses in CA3 region .(13. 90± 3. 63% ) was significantly greater than that in CA1 (10. 89±5. 06%, P<0. 001). The present study indicates that the somata of CA1 pyramidal neurons receive less GABAergic innervation than those of CA3 neurons, which may partially contribute to the selective vulnerability of hippocampal neurons following transeint forebrain ischemia.