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目的探讨新生期母婴分离(MS)对幼鼠内脏痛觉敏感性及脊髓背角Fos蛋白表达的影响。方法按析因设计,32只SD新生大鼠分成4组,每组8只,A1B1组为MS组并在6周龄时接受结直肠扩张刺激(CRD),A1B2组为MS组,6周龄未给予CRD,A2B1组未MS在6周龄接受CRD,A2B2组未MS,且6周龄未给予CRD。A1B1组、A2B1组6周龄时进行CRD下腹壁撤退反射(AWR)评分和痛阈测定;A1B1组、A2B1组幼鼠在CRD刺激后2h和A1B2组、A2B2组幼鼠一起处死,留取L6至S2脊髓,应用免疫组织化学染色及计算机图像分析系统进行脊髓Fos阳性(FLI)细胞数半定量分析。结果CRD压力为20、40、60、80mmHg时,A1B1组AWR评分分别为(2.2±0.7)、(3.2±0.6)、(3.8±0.4)、(4.0±0.0)分,A2B1组分别为(1.0±0.8)、(2.5±0.3)、(3.3±0.3)、(3.9±0.2)分;CRD为20、40、60mmHg时,两组差异有统计学意义。A1B1组和A2B1组痛阈值分别为(17.9±8.9)mmHg、(33.5±1.9)mmHg,差异有统计学意义(P=0.000)。A1B1组、A2B1组、A1B2组和A2B2组幼鼠腰骶段脊髓背角FLI细胞数分别为(18.3±3.4)、(11.4±1.1)、(14.3±1.3)和(9.1±0.4)个,新生期MS和幼鼠6周龄时CRD均可使幼鼠腰骶段脊髓背角FLI细胞数显著升高(P均<0.01)。结论新生期MS可导致幼鼠内脏痛觉敏感性增高和痛阈下降,脊髓初级中枢对内脏痛觉敏感化,接受伤害性CRD后引起脊髓神经元Fos蛋白高表达,出现慢性内脏痛觉高敏感性。
Objective To investigate the effects of neonatal maternal-fetal separation (MS) on visceral hyperalgesia and Fos protein expression in spinal dorsal horn of neonatal rats. Methods By factorial design, 32 SD neonatal rats were divided into 4 groups of 8 rats each. The A1B1 group was MS and received colorectal distention stimulation (CRD) at 6 weeks of age. The A1B2 group was MS, the 6-week-old No CRD was given, A2B1 did not receive CRD at 6 weeks, A2B2 did not have MS, and 6 weeks did not receive CRD. A1B1 group, A2B1 group 6 weeks of age CRD lower abdominal wall reflex (AWR) score and pain threshold determination; A1B1 group, A2B1 group of young rats CRD stimulation 2h and A1B2 group, A2B2 group of young rats were sacrificed, L6 To S2 spinal cord, semi-quantitative analysis of Fos-positive (FLI) cells in spinal cord was performed by immunohistochemical staining and computerized image analysis system. Results The AWR scores of the A1B1 group were (2.2 ± 0.7), (3.2 ± 0.6), (3.8 ± 0.4) and (4.0 ± 0.0) at CRD pressures of 20, 40, 60 and 80 mmHg, respectively ± 0.8), (2.5 ± 0.3), (3.3 ± 0.3) and (3.9 ± 0.2), respectively. There was significant difference between the two groups when the CRD was 20, 40 and 60 mmHg. The pain thresholds of group A1B1 and group A2B1 were (17.9 ± 8.9) mmHg and (33.5 ± 1.9) mmHg, respectively, with statistical significance (P = 0.000). The numbers of FLI cells in the lumbosacral spinal cord and dorsal horn of the rats in A1B1, A2B1, A1B2 and A2B2 groups were (18.3 ± 3.4), (11.4 ± 1.1), (14.3 ± 1.3) and (9.1 ± 0.4), respectively The number of FLI cells in lumbosacral spinal cord dorsal horn of young MS rats and CRD rats at 6 weeks old were significantly increased (all P <0.01). Conclusion Neonatal MS can lead to increased visceral hyperalgesia and decreased pain threshold in young rats. The primary spinal cord sensitizes to visceral hyperalgesia. Fos protein is highly expressed in spinal cord neurons after nociceptive CRD, and chronic visceral hyperalgesia appears.