大鼠腰骶髓和延髓星形胶质细胞及神经元对慢性结肠炎的反应

GFAP AND FOS IMMUNOREACTIVITY IN LUMBOSACRAL SPINAL CORD AND MEDULLA OBLONGATA IN RATS WITH CHRONIC COLONIC INFLAMMATION

目的探讨大鼠腰骶髓和延髓星形胶质细胞及神经元对慢性结肠炎的反应,及反应性星形胶质细胞和反应性神经元之间的关系.方法成年雄性SD大鼠,实验组（n=17）给予三硝基苯磺酸（TNBS）灌肠诱导结肠炎;对照组（n=16）给予生理盐水灌肠.免疫组织化学法显示大鼠腰骶髓和延髓内胶质原纤维酸性蛋白（GFAP）阳性星形胶质细胞和Fos阳性神经元.结果TNBS灌肠后,GFAP阳性星形胶质细胞主要分布在脊髓背角浅层（Ⅰ～Ⅱ层）、中间外侧核（Ⅴ层）、后连合核（Ⅹ层）和腹角外侧核（Ⅸ层）.Fos阳性神经元集中分布在背角深层（Ⅲ～Ⅳ,Ⅴ～Ⅵ层）.在延髓,两者均主要分布在由孤束核、中间网状带和腹外侧区组成的延髓内脏带（MVZ）.TNBS灌肠后3、7、14 d,脊髓中GFAP阳性细胞密度明显高于对照组（P＜0.05）.TNBS灌肠后3 d,延髓中GFAP阳性细胞密度明显高于对照组（P＜0.05）.TNBS灌肠后28 d,脊髓和延髓中GFAP阳性细胞密度下降,与对照组无显著性差异（P＞0.05）.结论结肠炎性刺激引起脊髓和延髓中星形胶质细胞激活.随着结肠炎的恢复,星形胶质细胞的反应性下降.在延髓内脏带,反应性星形胶质细胞与反应性神经元关系密切.

Objective To investigate the responses of astrocytes and neurons in rat lumbosacral spinal cord and medulla ohlongata induced by chronic colonic inflammation, and the relationship between activated astrocytes and neurons. Methods Thirty-three male Sprague-Dawley rats were randomly divided into two groups. induced by intraluminal administration of trinitrobenzenesulfonic acid （TNBS） In treated group （n = 17）, colonic inflammation was in rats; In non-treated group （n = 16）, saline was intraluminally administered. The lumbosacral spinal cord and medulla oblongata were removed 3, 7, 14 and 28 days after intraluminal administration and processed for anti-GFAP, Fos and GFAP/Fos immunohistochemistry. Results Most activated GFAP positive astrocytes were distributed in the superficial laminae （Ⅰ-Ⅱ）, intermediolateral nucleus （lamina Ⅴ）, posterior commissural nucleus （laminae Ⅹ） and anterolateral nucleus （laminae Ⅸ） in lumbosacral spinal cord. Fos positive neurons were mainly expressed in the deeper laminae of the spinal cord （Ⅲ-Ⅳ, Ⅴ-Ⅵ）. In the medulla oblongata, both GFAP-IR astrocytes and Fns-IR neurons were mainly distributed in medullary visceral zone （MVZ）, which is composed of the nucleus of solitary tract （NTS）, ventrolateral medulla （VLM） and intermediat reticular （IRt）. The density of GFAP positive astrocytes in the spinal cord in treated rats 3,7 and 14 days after TNBS administration was significantly higher than that in non-treated rats （P 〈 0.05）. The density of GFAP positive astrocytes in MVZ was significantly higher in treated rats 3 days after TNBS administration than that in the non-treated rats （P 〈 0.05）. The density of GFAP positive astrocytes in lumbosacral spinal cord and MVZ in treated rats 28 days after TNBS administration decreased and became comparable to that in non-treated rats （P 〉 0.05）. Conclusions The astrocytes in lumbosacral spinal cord and medulla oblongata can be activated by colonic inflammation. The response of astrocytes decreased with the recovery of the colonic inflammation. Activated astrocytes are closely related to activated neurons in MVZ.