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

摘要:

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3 h 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。

Abstract:

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 Sprague-Dawley 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.