[Damages and its mechanism of the blood brain barrier in rats with diabetes mellitus with depression].

ABSTRACT

OBJECTIVE: To investigate the expressions of key proteins type IV collagen (CoIV), zonula occludens-1(ZO-1), α-smooth muscle actin(a-SMA) and the mechanisms of the structural injuries of the blood brain barrier in the hippocampus of diabetic rats with depression. METHODS: After 14 days of high-fat diet, the rats were treated with streptozotocin (STZ, 38 mg/kg, iv). Then, the animals were randomly divided into 2 groups (n=15)the diabetic group and the diabetes mellitus with depression group. The normal rats were randomly divided into 2 groups(n=15)the control group and the depression group. Diabetic group and control group were kept in normal conditions. The diabetes mellitus with depression group and the depression group were treated with chronic unpredictable stress for 28 days. The levels of blood glucose were detected. The behavior changes of rats were evaluated by open-field test and Morris test. The blood brain barrier morphological changes were observed under the electron microscope. The expressions of CoIV, ZO-1 and a-SMA in rat hippocampal blood-brain barrier were detected by immunocytochemistry. RESULTS: Compared with control group, the level of blood glucose was increased,the number of autonomic activity was decreased, the escape latencies were significantly longer in the Morris water maze test, as well as the space exploration times were shortened in the diabetes mellitus with depression group (P<0.05, P<0.01). The endothelial cells of the hippocampus were blurred, the capillary lumen was narrow, and the peripheral glial cells were edema, the expressions of ZO-1 and a-SMA were decreased(P <0.05), while the expression of CoIV was increased(P <0.05). Compared with diabetic group, the number of autonomic activity in the diabetes mellitus with depression group was significantly decreased (P<0.01), the escape latencies were longer (P<0.05), the blood brain barrier capillary lumen was more narrow and the glial cell terminal edema was more obvious, the expression of a-SMA was decreased(P<0.05). CONCLUSIONS: The abnormal expressions of ZO-1, CoIV and -SMA, key proteins in the hippocampal blood brain barrier, may be involved in the mechanisms of structural damages of the blood brain barrier in diabetes mellitus with depression.