Hampson Aidan J, Grimaldi Maurizio
Laboratory of Cellular and Molecular Regulation, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA.
J Neurosci. 2002 Jan 1;22(1):257-64. doi: 10.1523/JNEUROSCI.22-01-00257.2002.
12-hydroxyeicosatetraenoic acid (12-HETE) is a neuromodulator that is synthesized during ischemia. Its neuronal effects include attenuation of calcium influx and glutamate release as well as inhibition of AMPA receptor (AMPA-R) activation. Because 12-HETE reduces ischemic injury in the heart, we examined whether it can also reduce neuronal excitotoxicity. When treated with 12-(S)HETE, cortical neuron cultures subjected to AMPA-R-mediated glutamate toxicity suffered up to 40% less damage than untreated cultures. The protective effect of 12-(S)HETE was concentration-dependent (EC50 = 88 nm) and stereostructurally selective. Maximal protection was conferred by 300 nm 12-(S)HETE; 300 nm 15-(S)HETE was similarly protective, but 300 nm 5-(S)HETE was less effective. The chiral isomer 12-(R)HETE offered no protection; neither did arachidonic acid or 12-(S)hydroperoxyeicosatetraenoic acid. Excitotoxicity was calcium-dependent, and 12-(S)HETE was demonstrated to protect by inactivating N and L (but not P) calcium channels via a pertussis toxin-sensitive mechanism. Calcium imaging demonstrated that 12-(S)HETE also attenuates glutamate-induced calcium influx into neurons via a pertussis toxin-sensitive mechanism, suggesting that it acts via a G-protein-coupled receptor. In addition, 12-(S)HETE stimulates GTPgammaS binding (indicating G-protein activation) and inhibits adenylate cyclase in forskolin-stimulated cultures over the same concentration range as it exerts its anti-excitotoxic and calcium-influx attenuating effects. These studies demonstrate that 12-(S)HETE can protect neurons from excitotoxicity by activating a G(i/o)-protein-coupled receptor, which limits calcium influx through voltage-gated channels.
12-羟基二十碳四烯酸（12-HETE）是一种在缺血期间合成的神经调质。其对神经元的作用包括减少钙内流和谷氨酸释放，以及抑制α-氨基-3-羟基-5-甲基-4-异恶唑丙酸受体（AMPA-R）的激活。由于12-HETE可减轻心脏的缺血损伤，我们研究了它是否也能减轻神经元兴奋性毒性。用12-（S）HETE处理后，遭受AMPA-R介导的谷氨酸毒性的皮质神经元培养物所受损伤比未处理的培养物少达40%。12-（S）HETE的保护作用呈浓度依赖性（半数有效浓度=88纳米）且具有立体结构选择性。300纳米的12-（S）HETE提供最大保护；300纳米的15-（S）HETE同样具有保护作用，但300纳米的5-（S）HETE效果较差。手性异构体12-（R）HETE没有保护作用；花生四烯酸或12-（S）-氢过氧化二十碳四烯酸也没有保护作用。兴奋性毒性是钙依赖性的，并且已证明12-（S）HETE通过百日咳毒素敏感机制使N型和L型（但不是P型）钙通道失活来发挥保护作用。钙成像显示，12-（S）HETE还通过百日咳毒素敏感机制减轻谷氨酸诱导的钙流入神经元，这表明它通过G蛋白偶联受体发挥作用。此外，在与其发挥抗兴奋性毒性和减轻钙内流作用相同的浓度范围内，12-（S）HETE刺激GTPγS结合（表明G蛋白激活）并抑制福斯高林刺激的培养物中的腺苷酸环化酶。这些研究表明，12-（S）HETE可通过激活G（i/o）蛋白偶联受体保护神经元免受兴奋性毒性，该受体可限制通过电压门控通道的钙内流。
