[Effect of gastrodin on bone tissue around implants in type 2 diabetic rats]

Objective: To study the effect of gastrodin on oxidative stress and bone tissue around implants in type 2 diabetes mellitus rats (T2DM), so as to provide therapeutic basis for the problems of poor osseointegration and long repair period of implants in type 2 diabetic patients, to provide the basis for the development of new therapeutic drugs. Methods: Forty SD rats aged 5 weeks were divided into control group (n=10) and model group (n=30). The model group was fed with high glycolipid diet for 4 weeks and injected with 35 mg/kg streptozocin. The T2DM were divided into diabetic group (n=10) and gastrodin group (n=10). Pure screw titanium implants were placed in the metaphysis of both tibia. Rats in gastrodin group were given gastrodin 13.6 mg/kg everyday, while the control group and diabetic group were given the same dose of saline solution. Blood glucose was measured every two weeks after operation in all rats. After 4 and 8 weeks, the contents of serum malondialdehyde (MDA) and superoxide dismutase (SOD) were measured to analyze the oxidative stress level in rats. The expression of anti-apoptosis protein [B cell lymphoma/lewkmia-2 (bcl-2)]and apoptosis protein [bcl-2-associated X protein (bax)] was analyzed by immunohistochemistry. HE staining and micro-CT scanning were used to analyze the osseointegration around the implants. Results: The blood glucose of gastrodin [(12.98±2.53), (13.64±1.96), (14.58±3.40) and (12.84±2.82) mmol/L] were significantly lower than that of diabetic group [(20.97±2.27), (17.94±3.76), (23.66±2.90) and (21.22±2.67) mmol/L] at corresponding time point (P<0.017). Four and 8 weeks following surgery, the MDA concentration in gastrodin group [(5.21±1.60) and (3.47±1.17) nmol/ml] was significantly lower than that in diabetic group [(11.42±5.11) and (7.31±1.37) nmol/ml] at the corresponding time points (P<0.017), while SOD activity in gastrodin group [(42.89±6.00) and (53.12±9.73) U/ml] was significantly higher than those in diabetic group [(27.09±6.11) and (32.08±2.97) U/ml] at the corresponding time points (P<0.017). Immunohistochemistry showed that the bcl-2 expression in gastrodin group was significantly higher than that in diabetic group at 4 and 8 weeks following surgery (P<0.017), while the bax expression in gastrodin group was significantly lower than that in diabetic group (P<0.017). Four weeks after surgery, the bone volume/tissue volume (BV/TV), connection density (Conn.D), trabecular number (Tb.N), trabecular thickness (Tb.Th) in gastrodin group were significantly higher than those in diabetic group (P<0.017). There was no significant difference in trabecular separation/spacing (Tb.sp) between gastrodin group and diabetic group (P<0.017). Eight weeks after surgery, the BV/TV, Tb.N in gastrodin group were significantly higher than those in the diabetic group (P<0.017). There was no significant difference in Conn.D between gastrodin group and diabetic group (P<0.017). There was no significant difference in Tb.Th and Tb.sp in three groups (P<0.017). The trabecular structure in gastrodin group was better than that in diabetic group by HE staining. Conclusions: Gastrodin can decrease blood glucose, improve oxidative stress, protect bone tissue from apoptosis and promote bone formation around implants in T2DM.