母婴分离大鼠脑一肠轴内P物质及其NK1受体的表达

目的研究P物质及其受体在新生期母婴分离大鼠模型脑-肠轴上的表达。方法将新生期Sprague-Dawley雄性大鼠随机分为两组：母婴分离组：在出生后第2~21天，使新生大鼠与哺乳期母鼠分离3h／d。对照组：在出生后第2~21天，不给予任何处理。成年后（出生后60d）给予结直肠球囊扩张（CRD），取远端结肠、腰骶段脊髓和中脑进行P物质和NKl受体免疫组化检测并定量分析。结果母婴分离组大鼠和对照组比较，结肠肌层P物质阳性面积百分数、结肠NKI受体阳性肌间神经丛数目、脊髓背角P物质阳性面积、脊髓背角NK1阳性分布积分、中脑导水管周围灰质（PAG）和中缝核（DR）内P物质阳性面积、中脑PAG和DR内NK1阳性分布积分差异均无统计学意义（P均〉0．05）。结论新生期母婴分离对P物质和NK1受体表达的影响不明显，P物质和NK1受体在母婴分离大鼠模型内脏感觉过敏发生机制中的作用可能不大。

Objective To study the expression and distribution of substance P and its receptor along brain-gut axis in neonatal maternal separation rats. Methods Male neonatal Sprague-Dawley rats were randomly divided into 2 groups： Maternal separation （ MS ） group exposed to a 3-hour daily maternal separation or Non-handling （ NH ） control group exposed to no handling on postnatal day 2-21. Colorectal distension （ CRD ） was performed in these rats in adulthood. Distal colon and lumbar-sacral spinal cord and midbrain were harvested for semi-quantitative analysis of substance P and NKI receptor expression using immunohistochemical methods before and after CRD. Results None of the elements of substance P system was altered by maternal separation. There was no significant difference in substance P positive area percentage, the number of NK1 receptor positive myenteric plexus, substance P positive area in dorsal horn, the NK1 positive score in dorsal horn, periaqueductal gray （ PAG ） and raphe nucleus （ DR ） ofmidbrain, the NK1 positive score in PAG and DR （ P〉0.05 ） . Conclusion s Neonatal maternal separation has no significant effect on the expression of substance P and NK 1 receptor, suggesting that substance P system play little role in the development of visceral hyperalgesia in neonatal maternal separation rat models.