高糖饲养致兔脊髓病变的初步探讨

Investigation of the spinal cord lesion in rabbit fed a high-glucose diet

目的通过高糖喂养新西兰兔,观察并了解其脊髓形态学、增殖细胞核抗原(PCNA)改变及其意义,初步探索高糖对脊髓的影响机制。方法取健康雄性新西兰大白兔30只,随机分为2组,15只饲以基础饲料为对照组;余15只予以高糖饮食为实验组。各组取3只兔子每4周抽取空腹血样,测血糖及胰岛素水平。分别于12周、24周后,各组取6只兔子取其脊髓(胸髓)行HE及透射电镜观察脊髓前角及后索变化情况,同时行其PCNA的免疫组化研究。结果①实验组血糖水平随时间升高,24周时最高,血糖变化具有统计学意(P<0.05)。②实验组胰岛素(INS)水平4周时达到高峰,之后逐步下降,胰岛素变化具有统计学意(P<0.05)。③光镜下,前角结构基本正常,实验组后索有不同程度的改变,轻者呈溶解变性、稀疏网状结构,重者出现空泡变性,局灶性脱髓鞘,严重者仅见少量残余的正常脊髓组织。④透射电镜下,前角结构基本正常,实验组后索为明显的不同程度改变,较重者疏松明显,脱髓鞘改变,板层间呈裂隙状、果冻卷样或丝状改变,轴浆见空泡变性,严重者轴索变性增多,并有多处断裂,轴浆萎缩、融解,后索改变具有统计学意义(P<0.05)。⑤PCNA免疫组化的研究偶可见极少数阳性细胞表达,无统计学意义。结论①高糖可导致脊髓损伤。②以侵犯脊髓后索为主,损伤程度随高糖饲养时间的延长而加重。

[ Objective ] This study was aimed at investigating the lesion mechanisms of hyperglycemia to spinal cord via observing and studying the alteration of proliferating cell nuclear antigen （PCNA） and morphology of spinal cord. [Methods] 30 Zelanian rabbits were divided into two groups randomly. One group （15 rabbits） was fed with normal diet and employed as control, whereas the other fed a high-glucose diet. Extract the fasting blood samples of 3 rabbits in both groups every 4 weeks, measuring their plasma glucose and insulin levels. At the end of 12 weeks and 24 weeks, 6 rabbit＇s spinal cords in every group were obtained to observe the alteration in ventricolumna and posterior funiculus, employing HE dyeing and transmission electron microscope. Simultaneously, immunohistochemistry was performed on PCNA. [Results] （1） plasma glucose levels were significantly increased in experimental group, with a time-dependent manner and the peak emerged at 24th week. （2） insulin levels were significantly increased in experimental group in preceding 4 weeks, after which were gradually decreased. （3） In experimental group, light microscope observation revealed that ventricolumnas were mostly normal, whereas the posterior funiculuses were altered with different degree, such as simply degeneration, sparsely distributed, vacuolar degeneration and local demyelination. （4） In experimental group, TEM observations revealed that ventricolumnas were mostly normal, whereas the posterior funiculuses were altered with different degree, from sparsely degeneration to axon rupture and disappear. （5） Immunohistochemistry of PCNA reveal rare positive cells, with no significant difference between two groups. [ Conclusion ] （1） Hyperglycemia impairs the spinal cord. （2） It principally injury the posterior funiculus with a time-dependent pattern.