内脏痛高敏感模型幼鼠脊髓背角脑源性神经营养因子表达变化及意义

Expression profiles of brain-derived neurotrophic factor in the spinal dorsal horn of young rats with visceral hypersensitivity

目的采用新生期母婴分离（NMS）建立幼鼠内脏痛高敏感模型,探讨脊髓背角脑源性神经营养因子（BDNF）表达和幼鼠内脏痛敏感性增高的关系。方法将32只新生Sprague-Dawley大鼠按2×2析因设计随机分成对照组、NMS组、结直肠扩张刺激组（CRD组）和CRD＋NMS组,每组8只。NMS组和CRD＋NMS组新生大鼠出生后第2~14天,每天与母鼠分离3h建立内脏痛高敏感模型,CRD组和对照组大鼠出生后不予任何处理;仅CRD组和CRD＋NMS组大鼠在6周龄时接受CRD刺激。采用SABC免疫组织化学方法检测各组幼鼠脊髓背角BDNF表达情况;根据BDNF阳性细胞百分比及显色强度计算免疫化学分数（IHS）。采用析因设计方差分析对脊髓背角BDNF阳性细胞百分比和IHS进行分析。结果 4组幼鼠两侧脊髓背角均有不同程度的BDNF阳性细胞表达,NMS组和CRD＋NMS组幼鼠BDNF阳性细胞百分比和IHS值均明显高于对照组（P〈0.05）。析因设计方差分析结果显示：NMS可导致幼鼠脊髓背角BDNF阳性细胞百分比和IHS值明显增加,单次CRD刺激不影响幼鼠脊髓背角BDNF阳性细胞IHS值,NMS和单次CRD刺激间不存在交互作用。结论 NMS导致幼鼠内脏痛高敏感可能与脊髓背角BDNF过度表达有关。

Objective To explore the relationship between the expression of brain-derived neurotrophic factor（BDNF） in the spinal dorsal horn and the increase in visceral hypersensitivity in young rats by establishing a young rat model of visceral hypersensitivity by neonatal maternal separation（NMS）. Methods Thirty-two newborn SpragueDawley rats were randomly and equally divided into four groups by a 2×2 factorial design： control, NMS, colorectal distension（CRD）, and NMS＋CRD. The newborn rats in the NMS and NMS＋CRD groups were subjected to 3-hour daily maternal separation from days 2 to 14 after birth to establish a model of visceral hypersensitivity, while the rats in the control and CRD groups received no treatment after birth. At 6 weeks after birth, the CRD and CRD＋NMS groups received CRD stimulation. The streptavidin-biotin complex immunohistochemical method was used to determine the expression of BDNF in the spinal dorsal horn. The immunohistochemical score（IHS） was calculated based on the percentage of BDNF-positive cells and color intensity. The percentage of BDNF-positive cells in the spinal dorsal horn and IHS were analyzed by factorial analysis of variance. Results The expression of BDNF was detected bilaterally in the spinal dorsal horn at different levels in the four groups. The percentage of BDNF-positive cells and IHS were significantly higher in the NMS and NMS＋CRD groups than in the control group（P〈0.05）. The results of factorial analysis of variance indicated that NMS significantly increased the percentage of BDNF-positive cells in the spinal dorsal horn and IHS; a single CRD stimulation had no effects on the IHS of BDNF-positive cells in the spinal dorsal horn; there was no interaction between NMS and a single CRD stimulation. Conclusions The over-expression of BDNF in the spinal dorsal horn may be involved in high visceral hypersensitivity in young rats induce by NMS.