Division of Anaesthesia, Critical Care and Pain Management, Department of Cardiovascular Sciences (Pharmacology and Therapeutics Group), University of Leicester, Leicester Royal Infirmary, Leicester LE1 5WW, UK.
Br J Anaesth. 2010 May;104(5):596-602. doi: 10.1093/bja/aeq067. Epub 2010 Mar 30.
Transient receptor potential vanilloid subtype 1 (TRPV1) receptor is a primary pain-sensing relay at peripheral sensory nerve endings and is also widespread in the brain, where it is implicated in neurodegeneration. Previous studies of TRPV1 neurotoxicity have utilized heterogeneous receptor populations, non-selective ligands, or non-neuronal cell types. Here, we explored the pharmacology of TRPV1-induced cytotoxicity in a homogeneous, neurone-like cellular environment.
Cell death was examined in a human neurone-like cell line, stably expressing recombinant human TRPV1. Cytotoxicity was quantified in terms of nuclear morphology and mitochondrial complex II activity. Immunocytochemical markers of apoptotic cell death were also examined.
The TRPV1-selective agonist capsaicin, and the endovanilloids anandamide and N-arachidonoyl-dopamine (NADA), induced TRPV1-dependent delayed cell death in a concentration- and time-dependent manner. Capsaicin exposure time was significantly correlated with potency (r(2)=0.91, P=0.01). Release of cytochrome c from mitochondria, activation of caspase-3, and condensed nuclear chromatin were evident 6 h after capsaicin exposure, but cytotoxicity was unaffected by a pan-caspase inhibitor (zVAD-fmk, 50 microM).
We conclude that capsaicin, anandamide, and NADA can initiate TRPV1-dependent delayed cell death in neurone-like cells. This is an apoptosis-like process, but independent of caspase activity.
瞬时受体电位香草酸亚型 1(TRPV1)受体是外周感觉神经末梢的主要疼痛感应中继器,在大脑中也广泛存在,它与神经退行性变有关。先前关于 TRPV1 神经毒性的研究利用了异质的受体群体、非选择性配体或非神经元细胞类型。在这里,我们在同质的神经元样细胞环境中研究 TRPV1 诱导的细胞毒性的药理学。
在稳定表达重组人 TRPV1 的人神经元样细胞系中检查细胞死亡。用核形态和线粒体复合物 II 活性来量化细胞毒性。还检查了凋亡细胞死亡的免疫细胞化学标记物。
TRPV1 选择性激动剂辣椒素和内源性香草酸酰胺和 N-花生四烯酰多巴胺(NADA)以浓度和时间依赖的方式诱导 TRPV1 依赖性延迟细胞死亡。辣椒素暴露时间与效力呈显著相关性(r²=0.91,P=0.01)。线粒体细胞色素 c 的释放、caspase-3 的激活和浓缩的核染色质在辣椒素暴露 6 小时后明显,但细胞毒性不受泛半胱天冬酶抑制剂(zVAD-fmk,50 μM)的影响。
我们得出结论,辣椒素、内源性香草酸酰胺和 NADA 可以在神经元样细胞中引发 TRPV1 依赖性延迟细胞死亡。这是一种类似于凋亡的过程,但不依赖于半胱天冬酶活性。