GDNF对局灶性脑缺血MRI及皮质和尾壳核神经干细胞增殖和分化的影响

观察胶质细胞源性神经营养因子(GDNF)对大鼠局灶性脑缺血磁共振成像(MRI)及皮质和尾壳核神经干细胞(NSCs)增殖和分化的影响,并探讨GDNF对内源性NSCs增殖分化的作用机制。制作右侧局灶性脑缺血模型,左侧脑室注射GDNF,5-溴脱氧尿核苷(BrdU)标记DNA合成期(S期)细胞,Y迷宫检测大鼠学习记忆能力,MRI观察脑部影像学变化,免疫组化法观察正常组、假手术组、缺血组、生理盐水组和GDNF组大鼠局灶性脑缺血90min后再灌注不同时间(3、7、14、21、28d)皮质和尾壳核内BrdU/nestin、BrdU/NeuN、BrdU/GFAP阳性双标细胞。GDNF组对学习记忆的恢复较模型组和生理盐水组明显;MRI检查T2WI上缺血区信号明显增高和轻微脑肿胀,GDNF组缺血后3d,缺血区出现小面积信号增高影,14d信号强度明显下降;GDNF组Br-dU/nestin双标细胞数明显增加;新生细胞分化结果显示28d时,GDNF组BrdU/NeuN(58.23%±15.30%)、BrdU/GFAP(11.29%±4.30%),与其它组相比均有显著性差异(P<0.05)。以上结果证实局灶性脑缺血激活皮质和尾壳核内的NSCs,而GDNF可促进内源性NSCs增殖、分化,从而促进学习记忆能力的恢复。

THE EFFECT OF GDNF ON THE PROLIFERATION AND DIFFERENTIATION OF NEURAL STEM CELLS AND MRI IN THE CORTEX AND CAUDOPUTAMEN OF ADULT RATS AFTER FOCAL CEREBRAL ISCHEMIA

To investigate the effect of glial cell-lined derived neurotrophic factor (GDNF) on magnetic resonance imaging (MRI) of brain and proliferation and differentiation of endogenetic neural stem cells in the cortex and caudoputamen in adult rats after focal cerebral ischemia, the right middle cerebral artery of rat was occluded for 90 minutes to establish transient focal cerebral ischemia reperfusion model. GDNF was injected into the left lateral ventricle under the stereo localization. Bromodeoxyuridine (BrdU) was uesd to label the S phase cells, Y-maze test to detect the recovery of learning and memory abilities of every adult rat, MRI to tract the change of the brain images of the rats and immunohistochemical method to observe BrdU positive cells, BrdU/nestin, BrdU/NeuN and BrdU/GFAP double positive cells in the cortex and caudoputamen of each rat from every group. Rats injected with GDNF recovered learning and memory abilities better than the control groups. High intensive signals and little swell could be observed in the right lateral cortex and caudoputamen of MCAO rats on T2WI sequence by MRI. On the 3 d after ischemia, a little high intensive signals appeared in ischemic area, and 14 days later, high intensive signals markedly descended in the GDNF group. The number of BrdU/nestin double positive cells was increased obviously in ischemic cortex and caudoputamen of rats injected with GDNF, and on 28 d in the groups of cellular rebirth and differentiation, the number of BrdU/neuN (58.23%±15.30%) and BrdU/GFAP (11.29%±4.30%) double positive cells compared with those of the control groups, there was a significant difference (P<0.05). These results indicate that GDNF might stimulate proliferation of endogenetic NSCs in the cortex and caudoputamen, the differentiation for neurons and the recovery of learning and memory abilities.