脑卒中后抑郁大鼠海马原位增殖的新生细胞存活和分化状态

目的 观察脑卒中后抑郁(post-stroke depression,PSD)大鼠海马原位增殖新生细胞的存活和分化.方法 采用左侧大脑中动脉阻塞(MCAO)联合慢性不可预见温和应激刺激(chronicmild stress,CMS)及孤养法建立PSD模型,将雄性SD大鼠分为假手术、脑卒中、CMS和PSD组.每组均为18只.采取免疫组织化学、荧光双标染色及共聚焦成像动态检测,比较各研究组大鼠左侧海马齿状回溴脱氧尿苷嘧啶(BrdU)及其与神经元特异性核蛋白(NeuN)或胶质纤维酸性蛋白(GFAP)共表达.结果 与脑卒中组(232.2±8.6、123.7±2.6、136.2±2.6)相比,PSD组大鼠左侧(伤侧)海马齿状回BrdU+细胞数在脑梗死后第21(156.2±2.5)、30(70.2±2.0)和45天(81.2±1.1)均明显减少(t=28.83、52.2、62.08,均P<0.01),但仍高于假手术组.与脑卒中组(79.3%±2.8%、87.7%±4.6%)相比,PSD组大鼠左侧(伤侧)海马齿状回BrdU+/NeuN+细胞比例在脑梗死后第30(69.0%±3.4%)和45天(78.3%±2.4%)均明显减少(t=5.871、4.403,均P<0.01).BrdU+/GFAP+细胞比例在脑梗死后30和45 d均明显增加(t=4.226、8.945,P<0.01).结论 PSD大鼠脑卒中后海马齿状回原位增殖的新生细胞存活降低,分化为神经元的比例下降,胶质细胞比例增加.

Survival and differentiation of endogenous neural stem cells in the hippocampus of post-stroke depression rats

Objective To investigate the proliferation and survival of endogenous new born cells in the hippocampus of post-stroke depression (PSD) rats. Methods Male SD rats were divided into 4 groups (n = 18): control, stroke, depression and PSD group. The animals were subjected to left middle cerebral artery occlusion (MCAO) reaulting in consistent focal cerebral infarcts, followed by an 18-day exposure to chronic mild stress (CMS) and single housing to induce PSD animal model The dynamic expression of brodmodeoxyuridine (BrdU), neuron-specific nuclear protein (NeuN) and glial fibrillary acidic protein (GFAP) in the left dentate gyrus of hippocampus were determined by immunohistochemistry or double-lable immunofluorescence staining. BrdU was a marker of new born cell, NeuN and GFAP marked that new born cell differentiated into neuron and astrocyto respectively. Results Compared with ischemia animals (232.2±8.6,123.7±2.6,136.2±2.6), in the left dentate gyrus, PSD samples had significantly less BrdU-positive cells ( 156.2±2.5, t =28.83, P < 0.01 ) on the 21st day after ischemia, and on day 30 and 45 ( 70.2±2.0, 81.2±1.1, t = 52.27, 62.08, both P < 0.01 ). The ratio of BrdU-positive cells to NeuN had decreased on day 30 (79.3%±2.8% vs 69.0%±3.4%, t =5.871, P < 0.01 )and day 45 (87.7% ±4.6% vs 78.3%±2.4%, t =4.403, P < 0.01) in PSD animals. There was a statistically significant increased proportion of BrdU-positive cells co-stained with GFAP in PSD animals compared with the ischemia ones on day 30 and45 (t =4.226, 8.945, both P < 0.01). Conclusion CMS following ischemia exerts an inhibitory effect on hippocampal survival of new born cells as well as their differentiation into neurons, while promotes new born cells differentiating into astrocytes.