Semkova I, Wolz P, Schilling M, Krieglstein J
Institut für Pharmakologie und Toxikologie, Fachbereìch Pharmazie and Lebensminelchemle, Philipps-Universität, Marburg, Germany.
Eur J Pharmacol. 1996 Nov 7;315(1):19-30. doi: 10.1016/s0014-2999(96)00593-6.
It has been previously demonstrated that selegiline, an irreversible monoamine oxidase B (MAO-B) inhibitor, potentiates glial reaction to injury and possesses some 'trophic-like' activities which do not depend on the inhibition of MAO-B and which are probably associated with the induction of astrocyte-derived neurotrophic substances. Based on these findings, we tried to find out whether selegiline is able to modify the expression of nerve growth factor (NGF) and to protect central nervous system (CNS) neurons from excitotoxic and ischemic damage. Selegiline (10 pM-1 nM) induced NGF messenger RNA (mRNA) expression in cultured rat cortical astrocytes as determined by reverse transcription-polymerase chain reaction (RT-PCR) followed by a corresponding increase in NGF protein content measured by two-site NGF-enzyme-linked immunosorbent assay (ELISA) in astrocyte-conditioned medium. Additionally, exposure of hippocampal cultures containing neuronal and glial cells to this drug at the same concentrations enhanced significantly the content of NGF measured in the culture medium after 6 h of incubation. We hypothesize that selegiline could rescue hippocampal neurons from injury by induction of astrocyte-derived NGF in this cell culture system. To test this hypothesis, an excitotoxic damage was induced in the same type of cells by exposure to 0.5 mM L-glutamate for 1 h. Selegiline (10 pM-1 nM) present in the growth medium 6 h before until 18 h after induction of injury (the point of glutamate-toxicity measurement) protected hippocampal neurons from excitotoxic death. Furthermore, administered intraperitoneally (i.p.) (8 x 15 mg/kg per day) this drug enhanced the expression of NGF message in intact rat cerebral cortex and protected rat cortical tissue from ischemic insult due to permanent occlusion of the middle cerebral artery (MCA). The neuroprotective activity of selegiline (5 x 10 mg/kg per day i.p.) was also demonstrated in a mouse model of focal cerebral ischemia. The present data show that selegiline induced NGF expression in cultured rat cortical astrocytes. In mixed primary cultures of hippocampal neuronal and glial cells, selegiline increased NGF protein content and protected hippocampal neurons from excitotoxic degeneration. In vivo, this drug induced NGF gene expression in cerebral cortex from intact rats and protected rat and mouse cortical tissue from ischemic insult after occlusion of the MCA. Our results indicate that the induction of astrocyte-derived NGF could contribute to the neuroprotective activity of selegiline demonstrated both in vivo and in vitro and can explain, in part, the 'trophic-like' properties of this compound which has been observed by others.
先前的研究表明，司来吉兰作为一种不可逆的单胺氧化酶B（MAO - B）抑制剂，可增强胶质细胞对损伤的反应，并具有一些“营养样”活性，这些活性不依赖于MAO - B的抑制作用，可能与星形胶质细胞衍生的神经营养物质的诱导有关。基于这些发现，我们试图探究司来吉兰是否能够改变神经生长因子（NGF）的表达，并保护中枢神经系统（CNS）神经元免受兴奋性毒性和缺血性损伤。通过逆转录 - 聚合酶链反应（RT - PCR）测定，司来吉兰（10 pM - 1 nM）可诱导培养的大鼠皮质星形胶质细胞中NGF信使核糖核酸（mRNA）的表达，随后通过双位点NGF酶联免疫吸附测定（ELISA）测量星形胶质细胞条件培养基中NGF蛋白含量相应增加。此外，将含有神经元和胶质细胞的海马培养物暴露于相同浓度的该药物中，孵育6小时后，培养基中测量的NGF含量显著增加。我们推测，在这种细胞培养系统中，司来吉兰可通过诱导星形胶质细胞衍生的NGF来挽救海马神经元免受损伤。为了验证这一假设，通过将细胞暴露于0.5 mM L - 谷氨酸1小时，在同一类型的细胞中诱导兴奋性毒性损伤。在损伤诱导前6小时直至损伤诱导后18小时（谷氨酸毒性测量时间点）存在于生长培养基中的司来吉兰（10 pM - 1 nM）可保护海马神经元免受兴奋性毒性死亡。此外，腹腔注射（i.p.）（每天8×15 mg/kg）该药物可增强完整大鼠大脑皮质中NGF信息的表达，并保护大鼠皮质组织免受大脑中动脉（MCA）永久性闭塞所致的缺血性损伤。司来吉兰（每天i.p. 5×10 mg/kg）的神经保护活性在局灶性脑缺血小鼠模型中也得到了证实。目前的数据表明，司来吉兰可诱导培养的大鼠皮质星形胶质细胞中NGF的表达。在海马神经元和胶质细胞的混合原代培养物中，司来吉兰增加了NGF蛋白含量，并保护海马神经元免受兴奋性毒性退变。在体内，该药物可诱导完整大鼠大脑皮质中NGF基因的表达，并在MCA闭塞后保护大鼠和小鼠皮质组织免受缺血性损伤。我们的结果表明，星形胶质细胞衍生的NGF的诱导可能有助于司来吉兰在体内和体外均表现出的神经保护活性，并且可以部分解释该化合物已被其他人观察到的“营养样”特性。
