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

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

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（chronic mild 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45d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。

Objective To investigate the proliferation and survival of endogenous new born cells in the hippocarnpus 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） reauhing 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 gyms 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 astrocyte respectively. Results Compared with ischemia animals （ 232. 2±8.6,123.7±2. 6,136. 2±2. 6 ） , in the left dentate gyms, 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 and 45 （ 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.