低频重复经颅磁刺激对大鼠海马CA3区KCa1．1、NaV1．6、NMDAR1和GAD65表达的影响

Low-frequency transcranial magnetic stimulation and the expression of Kcal. 1, Navl.6, NMDAR1 and GAD65 proteins in the CA3 region of the hippocampus

目的观察低频重复经颅磁刺激（rTMS）对健康sD大鼠海马CA3区Kca1．1、Na 1．6、NMDAR1和GAD65表达的影响。方法雄性sD大鼠50只，按随机数字表法分为磁刺激组和假刺激组，每组25只。磁刺激组大鼠给予连续14d的磁刺激治疗，假刺激组给予相应的“假性”刺激。磁刺激组治疗结束后，各组又按处死大鼠的不同时间点进一步分为5个亚组，即6h亚组、24h亚组、1周亚组、3周亚组和6周亚组，每亚组5只大鼠。采用免疫组化检测各时间点大鼠海马CA3区锥体细胞层Kca1．1、Na 1．6、NMDAR1和GAD65蛋白的表达，并进行统计学比较和分析。结果海马CA3区锥体细胞层Kca1．1阳性神经元密度在rTMS后6h至3周均明显增高，与假刺激组比较，差异有统计学意义（P〈0．01）；而GAD65阳性神经元密度在rTMS后6h也明显增高（P〈0．05），且在rTMS后24h至3周增加更为显著，与假刺激组比较，差异有统计学意义（P〈0．01）。CA3区锥体细胞层Na 1．6阳性神经元密度仅在rTMS后6h短暂下降，与假刺激组比较，差异有统计学意义（P〈0．05）；而NMDAR1阳性神经元密度在rTMS后6h也呈短暂下降，与假刺激组比较，差异有统计学意义（P〈0．01）。结论低频rTMSI能上调健康SD大鼠海马CA3区锥体细胞层Kca1．1和GAD65蛋白的表达，且可持续至少3周；仅短暂下调Na 1．6、NMDAR1蛋白的表达，这可能是低频rTMS预处理后大鼠具有抗痫作用的部分原因。

Objective To investigate whether repeated low-frequency transcranial magnetic stimulation （rTMS） can affect the expression of Kcl. 1, Navl. 6, NMDAR1 and/or GAD65 protein in the pyramid layer of the CA3 region of the hippocampus. Methods Fifty rats were randomly divided into an experimental group and a sham group. The former was administered low-frequency rTMS on 14 consecutive days; the latter were given sham stimula- tion for 14 days. After the protocols were completed, each group was sub-divided into 6 h, 24 h, 1 week, 3 week and 6 week sub-groups. The rats of each sub-group were sacrificed at the corresponding time points and the expression of Kcl. 1, Navl. 6, NMDAR1 and GAD65 in the CA3 region of the hippocampus was examined using immunohisto- chemical techniques. Results Compared with the sham group, Kcl. 1-positive neuron densities increased signifi- cantly in the period 6 h to 3 weeks after rTMS. GAD65-positive neuron densities were also elevated significantly from 6 h to 3 weeks. Nav 1.6- and NMDARl-positive neuron densities decreased transiently at 6 h after the completion of the rTMS protocol. Conclusions These results show that low-frequency rTMS can upregulate the expression of Kcal. 1 and GAD65, and that the effect lasts for at least 3 weeks. It transiently downrcgulates the expression of Nav 1.6 and NMDAR1 in the hippocampal CA3 region, at least in rats. These changes may be one of its anti-epileptic mechanisms.