Inhibition of p75 neurotrophin receptor attenuates isoflurane-mediated neuronal apoptosis in the neonatal central nervous system.
Inhibition of p75 neurotrophin receptor attenuates isoflurane-mediated neuronal apoptosis in the neonatal central nervous system.
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DOI：
10.1097/aln.0b013e31819b602b
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发表时间：
2009-04
期刊：
影响因子：
8.8
通讯作者：
Patel PM
中科院分区：
文献类型：
--
作者：
Head BP;Patel HH;Niesman IR;Drummond JC;Roth DM;Patel PM
在突触发生期间暴露于麻醉剂会导致细胞凋亡和随后的成年认知功能障碍。原脑源性神经营养因子(ProBDNF)参与突触形成，并可通过p75神经营养受体(P75NTR)诱导神经元凋亡。ProBDNF被纤溶酶切割成成熟的BDNF(MBDNF)，纤溶酶是一种由tPA转化为纤溶酶原的蛋白酶，在神经元活性的作用下释放出来；mBDNF通过TrkB受体支持生存和稳定突触。我们假设麻醉药抑制tPA从神经元释放，增强p75NTR信号，减少突触导致细胞凋亡。将原代神经元(DIV5)和出生后5-7天(PND5-7)小鼠暴露于5%CO2、95%空气中的异氟醚(1.4%，4h)。半胱氨酸天冬氨酸氨基转移酶-3(Caspase-3，CSP3)免疫印迹和免疫荧光显微镜检测细胞凋亡。用神经元棘标记物Drebrin评价树突棘的变化。用电子显微镜观察PND5-7小鼠海马区突触的变化。原代神经元在异氟醚前15分钟暴露于tPA、纤溶酶或p75NTR的药物抑制剂(Fc-p75NTR或TAT-Pep5)。PND5-7小鼠在注射异氟醚前15分钟，腹腔注射TAT-Pep5。体外培养的神经元(DIV5)暴露于异氟醚后，培养上清液中的tPA减少，DREBRIN的表达(树突状丝状足棘的标志)减少，而Cl-Csp3的表达增加。TPA、纤溶酶或TAT-Pep5能稳定树突丝足棘，减少神经元中的Cl-Csp3。TAT-Pep5可阻断异氟烷诱导的PND5-7小鼠海马区Cl-Csp3的增加和突触的减少。在体外，TPA、纤溶酶或p75NTR抑制可阻断异氟烷介导的树突丝足棘减少和神经元凋亡。异氟醚减少了PND5-7小鼠海马区的突触，增强了Cl-Csp3，后者可被体内p75NTR抑制而减轻。这些数据支持这一假说，即异氟醚对发育中的啮齿动物脑的神经毒性是通过减少突触tPA释放和增强proBDNF/p75NTR介导的细胞凋亡来介导的。
Exposure to anesthetics during synaptogenesis results in apoptosis and subsequent cognitive dysfunction in adulthood. Probrain derived neurotrophic factor (proBDNF) is involved in synaptogenesis and can induce neuronal apoptosis via p75 neurotrophic receptors (p75NTR). proBDNF is cleaved into mature BDNF (mBDNF) by plasmin, a protease converted from plasminogen by tPA that is released with neuronal activity; mBDNF supports survival and stabilizes synapses through TrkB receptors. We hypothesized that anesthetics suppresses tPA release from neurons, enhances p75NTR signaling, reduces synapses resulting in apoptosis. Primary neurons (DIV5) and postnatal day 5-7 (PND5-7) mice were exposed to isoflurane (1.4%, 4 h) in 5% CO2, 95% air. Apoptosis was assessed by cleaved caspase-3 (Cl-Csp3) immunoblot and immunofluorescence microscopy. Dendritic spine changes were evaluated with the neuronal spine marker, drebrin. Changes in synapses in PND5-7 mouse hippocampi were assessed by electron microscopy. Primary neurons were exposed to tPA, plasmin, or pharmacologic inhibitors of p75NTR (Fc-p75NTR or TAT-Pep5) 15 min prior to isoflurane. TAT-Pep5 was administered by intraperitoneal injection to PND5-7 mice 15 min prior to isoflurane. Exposure of neurons in vitro (DIV5) to isoflurane decreased tPA in the culture medium, reduced drebrin expression (marker of dendritic filopodial spines) and enhanced Cl-Csp3. tPA, plasmin or TAT-Pep5 stabilized dendritic filopodial spines and decreased Cl-Csp3 in neurons. TAT-Pep5 blocked isoflurane-mediated increase in Cl-Csp3 and reduced synapses in PND5-7 mouse hippocampi. tPA, plasmin, or p75NTR inhibition blocked isoflurane-mediated reduction in dendritic filopodial spines and neuronal apoptosis in vitro. Isoflurane reduced synapses and enhanced Cl-Csp3 in the hippocampus of PND5-7 mice, the latter effect being mitigated by p75NTR inhibition in vivo. These data support the hypothesis that isoflurane neurotoxicity in the developing rodent brain is mediated by reduced synaptic tPA release and enhanced proBDNF/p75NTR-mediated apoptosis.