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目的:探讨刺激大鼠背侧海马对脑干部分神经核团生长抑素(SOM)mRNA表达的影响,分析海马在痛调制中的作用机制。方法:健康成年wistar大鼠40只,随机分为4组。A组:正常对照组,不给动物任何处理;B组:疼痛刺激组,大鼠右侧后肢足底皮下注射4 g/L多聚甲醛200μl,作为疼痛模型。C组:电刺激组,将疼痛模型动物经腹腔注射20 mg/L戊巴比妥钠麻醉后,借助于脑立体定位仪,待大鼠清醒后,按Paxinos和watson大鼠脑图谱,用同心圆电极于大鼠右背侧海马给予方波电刺激,时间为2 min。D组:电刺激对照组,操作同电刺激组但不通电,时间为2 min。 4组动物均于12 h后处死,经主动脉灌注,冰冻切片,采用地高辛标记反义RNA探针原位杂交及计算机图像分析技术,分别检测中脑导水管周围灰质(PAG),中缝大核(NRM)和外侧网状核(LRN)SOM mRNA阳性神经元细胞数及光密度值。结果:疼痛刺激后,PAG、NRM、LRN内SOM mRNA表达较正常明显增高(P<0.01),电刺激组PAG、LRN的SOM mRNA表达较疼痛刺激组进一步增加,而NRM内SOM mRNA较疼痛刺激组增加不明显。结论:海马兴奋可引起PAG、LRN神经元SOM mRNA表达增加,因此,SOM可能与脑干PAG和LRN参与镇痛有关。
Objective: To investigate the effect of stimulating the dorsal hippocampus on the expression of somatostatin (SOM) mRNA in the brainstem nuclei and to analyze the mechanism of action of hippocampus in pain modulation. Methods: Forty adult healthy wistar rats were randomly divided into 4 groups. Group A: normal control group, no animal treatment; Group B: pain stimulation group, rats right hind limbs subcutaneous injection of 4 g / L paraformaldehyde 200μl, as the pain model. Group C: The electrical stimulation group, the pain model animals were injected intraperitoneally with 20 mg / L pentobarbital sodium anesthesia, with the help of brain stereotaxic instrument, until the rats awake, according to Paxinos and watson rat brain map, with concentric Circular electrodes in the right dorsal hippocampus to give square wave electrical stimulation, time was 2 min. Group D: electrical stimulation control group, the same electrical stimulation group but no electricity, the time was 2 min. All animals were sacrificed 12 h later. After aorta perfusion and frozen section, the antisense RNA probe of digoxigenin was used for in situ hybridization and computer image analysis to detect the contents of periaqueductal gray (PAG), mid Nuclear number and optical density of SOM mRNA positive neurons in the nucleus (NRM) and lateral reticular nucleus (LRN) Results: SOM mRNA expression in PAG, NRM and LRN was significantly higher than that in normal control group (P <0.01). SOM mRNA expression in PAG and LRN of electrical stimulation group was increased more than that in pain stimulation group, while SOM mRNA in NRM group was more painful stimulus Group increase is not obvious. Conclusion: Hippocampal excitation can induce the increase of SOM mRNA expression in PAG and LRN neurons. Therefore, SOM may be related to the involvement of PAG and LRN in the brainstem.