慢性应激及氟西汀治疗后大鼠海马细胞支架的改变

目的 探讨慢性不可预见性应激及氟西汀治疗后大鼠细胞支架微管系统的动态性变化及其可能机制.方法 将24只大鼠按随机数字表法分为对照组(空白对照+生理盐水)、慢性不可预见性温和应激(CUMS)组(CUMS+生理盐水)和氟西汀组(CUMS+氟西汀),每组8只.对大鼠进行连续21 d CUMS后,氟西汀组给予氟西汀(10 mg/kg)治疗21 d,对照组和CUMS组给予生理盐水.实验结束后进行行为学观察,并使用免疫印迹法(western blot)检测大鼠海马乙酰化微管蛋白(Acet-Tub),酪氨酸化微管蛋白(Tyr-Tub),微管结合蛋白2(MAP-2)及磷酸化微管结合蛋白2(phospho-MAP-2).结果 (1)CUMS组糖水偏好[(55.13±11.80)%],总行程[(2736.59±511.20)cm],运动平均速度[(5.69±1.08)cm/s]及直立次数[(2.50±2.00)次]均低于对照组,差异有统计学意义(P＜0.01);氟西汀组上述指标与对照组比较差异无统计学意义(P＞0.05).(2)CUMS组与对照组相比,Acet-Tub表达升高[(171.84±10.34)%],Tyr-Tub[(62.06±9.24)%]和phospho-MAP-2[(68.81±8.93)%]的表达降低,差异有统计学意义(P均＜0.01),MAP-2的表达与对照组比较无统计学意义(P＞0.05);经氟西汀治疗后,Acet-Tub的表达降低为[(96.18±8.92)%],Tyr-Tub和phospho-MAP-2的表达分别升高为[(95.06±8.00)%]、[(100.60±7.30)%],与对照组比较均无统计学意义(P＞0.05).结论 慢性应激后微管动态性减低,神经可塑性受损,氟西汀可以逆转海马的这些损伤,上述过程可能与微管相关蛋白磷酸化水平的变化有关.

Behavioral and hippocampal cytoskeletal alterations in rats following chronic unpredictable mild stress and fluoxetine treatment

Objective To investigate behavior and hippocampal cytoskeletal alterations in rats following chronic unpredictable mild stress and fluoxetine treatment, and explore the possible mechanism. Methods Twenty four male Sprague-Dawley (SD) rats were divided into three groups, with 8 exposed to 21 consecutive days of chronic unpredicted mild stresses (CUMS) and treated with vehicle, 8 exposed to CUMS and treated with fluoxetine, and 8 as normal controls. Behavioral changes in these rats were analyzed in an Open-Field paradigm. The expressions of hippocampal cytoskeletal microtubulin were analyzed using western blot. Results ( 1 ) Compared with the normal rats, sucrose preference[ (55.13 ±11.80)%], total traveling distance [ (2736.59 ± 511.20) cm], velocity [ (5.69 ± 1.08) cm/s] and frequencies of rearing[ ( 2.50 ± 2.00 ) times ] were reduced ( P ＜ 0.01 ) in the CMS rats. These behavioral changes could be reversed after 21-day fluoxetine treatment. (2) Compared with the normal rats, the Acet-Tub expression [(171.84 ± 10.34)%] of CUMS group showed significant increase (P ＜0.01 ) in rats submitted to CUMS and Tyr-Tub expression [ (62.06 ± 9.24 )% ] of CUMS group was significantly decreased following CUMS stress (P ＜ 0.01 ). At the same time, MAP-2 expression did not change while phosphor MAP-2 expression [ (68.81 ± 8.93)% ] decreased significantly. These cytoskeletal changes could also be reversed after 21-day fluoxetine treatment. Conclusion These findings provide evidence that rats exposed to stress showed impairment of cytoskeletal microtubular dynamic and structural neuronal plasticity,this effect appears to be mediated by the degree of phosphorylation of MAP-2.