高脂饲料配合链脲佐菌素诱导2型糖尿病模型大鼠的椎间盘形态

Morphology of the intervertebral disc in high fat combined with streptozotocin-induced type II diabetic rats

背景:高脂饲料配合低剂量链脲佐菌素诱导大鼠2型糖尿病模型是目前常用的2型糖尿病动物模型,目前尚无此模型对椎间盘结构影响的相关报道。椎体终板硬化是造成椎间盘退变的重要因素之一。目的:评估高脂饲料配合低剂量链脲佐菌素诱导2型糖尿病大鼠模型是否适用于2型糖尿病相关椎间盘退变研究。方法:32只3月龄雌性SPF级SD大鼠随机分为4组,即假手术组、双侧卵巢切除组、糖尿病组、双侧卵巢切除+糖尿病组,每组8只。分别进行双侧卵巢切除术和/或高脂饲料配合低剂量链脲佐菌素处理。监测各组大鼠体质量、血糖及糖耐量,链脲佐菌素处理后8周检测骨密度后处死动物,取L_(5-6)节段脱钙后正中矢状位切片行VG染色并进行椎间盘退变评分,分析椎间盘高度和终板厚度。结果与结论:(1)糖尿病组和双侧卵巢切除+糖尿病组大鼠空腹血糖、随机血糖分别显著高于假手术组和双侧卵巢切除组(P<0.05),糖尿病组和双侧卵巢切除+糖尿病组大鼠胰岛素敏感性分别显著低于假手术组和双侧卵巢切除组(P<0.05);(2)双侧卵巢切除组L_4-L_6椎体骨密度显著低于假手术组(P<0.05),糖尿病组和双侧卵巢切除+糖尿病组L_5-L_6椎体骨密度均显著低于假手术组(P<0.05);(3)双侧卵巢切除组和双侧卵巢切除+糖尿病组L_5-L_6椎间盘退变评分分别显著高于假手术组和糖尿病组(P<0.05);双侧卵巢切除+糖尿病组表现与双侧卵巢切除组相仿,可见髓核细胞软骨化生及黏液变性,其评分结果显著高于假手术组和糖尿病组(P均<0.05),但与双侧卵巢切除组相比差异未见显著性意义;(4)与假手术组相比,双侧卵巢切除组和双侧卵巢切除+糖尿病组椎间盘高度明显降低(P<0.05);4组间终板厚度差异无显著性意义;(5)综上所述,虽然高脂饲料配合低剂量链脲佐菌素诱导2型糖尿病大鼠模型具备糖尿病特征表现,但未观察到其间盘组织较正常大鼠有显著改变,可能不适于2型糖尿病相关椎间盘退变研究。

BACKGROUND：Rat models of diabetes mellitus type 2 （T2DM） are usually induced by the combination of high-fat diet and low-dose streptozotocin, but their effects on the intervertebral disc have not yet been reported. Endplate sclerosis is an important factor contributing to intervertebral disc degeneration. OBJECTIVE：To evaluate whether the rat T2DM model induced by high-fat diet combined with low-dose streptozotocin is suitable for the study of T2DM related intervertebral disc degeneration. METHODS：Thirty-two 3-month-old female Sprague-Dawley rats were divided into four groups （n=8 per group）, including sham, bilateral variectomy, DM, and bilateral variectomy plus DM groups, followed by subjected to bilateral ovariectomy and/or high-fat diet combined with low-dose streptozotocin, respectively. The blood glucose level, body mass and glucose tolerance were determined. The bone mineral density of the lumbar spine was measured after 8-week streptozotocin treatment. The L5-6 segments were removed and cut through midst sagittal plane after decalcification, and then underwent Von Gieson staining and histological degeneration scoring, and the disc height and endplate thickness were measured. RESULTS AND CONCLUSION：Fasting blood glucose and random blood glucose levels in the DM and bilateral variectomy plus DM groups were significantly higher than those in the other two groups, and the insulin sensitivity in the DM and bilateral variectomy plus DM groups were significantly lower than that in the other groups （P〈0.05）. L4-6 vertebral bone mineral density in the bilateral variectomy group was significantly lower than that in the sham group （P〈0.05）;L5-6 vertebral bone mineral density in the DM and bilateral variectomy plus DM groups was significantly lower than that in the sham group （P〈0.05）. L5-6 vertebral histological scores in the DM and bilateral variectomy plus DM groups were significantly higher than those in the other groups （P〈0.05）. Similar with the bilateral variectomy group, there were chondrometaplasia and mucoid degeneration of nucleus pulposus cells in the bilateral variectomy plus DM group, and the histological scores were significantly higher than those in the sham and DM groups （P〈0.05）. Compared with the sham group, the intervertebral disc height in the bilateral variectomy and bilateral variectomy plus DM groups was significantly decreased （P〈0.05）. While, there was no significant difference in the endplate thickness among groups. These results indicate the combination of high-fat diet and low-dose streptozotocin-induced rat T2DM models possess diabetic characteristics, but the rat intervertebral disc tissues show no significant differences from the normal ones;therefore, this model may be unsuitable for the study on T2DM-related intervertebral disc degeneration.