Morphology of the intervertebral disc in high fat combined with streptozotocin-induced type Ⅱ diabetic rats / 中国组织工程研究

ABSTRACT

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.