Functional lipidomics. Calcium-independent activation of endocannabinoid/endovanilloid lipid signalling in sensory neurons by protein kinases C and A and thrombin.
Functional lipidomics. Calcium-independent activation of endocannabinoid/endovanilloid lipid signalling in sensory neurons by protein kinases C and A and thrombin.
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功能脂质组学。
DOI：
10.1016/j.neuropharm.2008.01.010
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发表时间：
2008
影响因子：
4.7
通讯作者：
Vellani V
中科院分区：
文献类型：
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作者：
Vellani V
N-花生四烯基乙醇胺(anandamine，AEA)是一种完整的大麻类CB1受体和“瞬时受体电位香草素”1型(TRPV1)通道激动剂，而N-棕榈酰乙醇胺(PEA)可增强这一作用。在大鼠背根神经节(DRG)神经元中，TRPV1既可被AEA激活和/或增敏，也可被蛋白激酶C(PKC)和蛋白激酶A(PKA)激活。我们在这里研究了DRG神经元中PKC和PKA激活物的AEA水平的影响。AEA水平被典型的PKC激活剂佛波酯(PMA)和腺苷环化酶激动剂Forsklin(FSK)以及通过刺激蛋白酶激活受体(PARs)激活PKC的凝血酶显著升高。另一种内源性大麻素和TRPV1非活性化合物2-花生四烯基甘油(2-AG)的水平仅在凝血酶作用下升高，且幅度小于AEA，而PEA不受任何处理的影响。重要的是，FSK和PMA诱导的AEA水平的升高对BAPTA-乙酰氧甲基(AM)酯与细胞内钙离子的螯合不敏感。在人胚胎肾(HEK-293)细胞中，凝血酶、PMA和FSK可升高AEA水平，前两种化合物的作用可被PKC抑制剂RO318220所抵消，而FSK的作用可被PKA抑制剂RpcAMPs所减弱。总之，我们报道了直接或在凝血酶受体激活后，PKC和PKA都能刺激AEA水平，可能不依赖于细胞内钙离子。由于AEA激活了TRPV1，这些发现可能表明感觉神经元中存在该受体的扩大级联。
N-arachidonoylethanolamine (anandamide, AEA), is a full agonist at both cannabinoid CB1receptors and “transient receptor potential vanilloid” type 1 (TRPV1) channels, and N-palmitoylethanolamine (PEA) potentiates these effects. In neurons of the rat dorsal root ganglia (DRG), TRPV1 is activated and/or sensitised by AEA as well as upon activation of protein kinases C (PKC) and A (PKA). We investigated here the effect on AEA levels of PKC and PKA activators in DRG neurons. AEA levels were significantly enhanced by both phorbol-miristoyl-acetate (PMA), a typical PKC activator, and forskolin (FSK), an adenylate cyclase stimulant, as well as by thrombin, which also activates PKC by stimulating protease-activated receptors (PARs). The levels of the other endocannabinoid and TRPV1-inactive compound, 2-arachidonoylglycerol (2-AG), were enhanced only by thrombin and to a lesser extent than AEA, whereas PEA was not affected by any of the treatments. Importantly, FSK- and PMA-induced elevation of AEA levels was not sensitive to intracellular Ca2+chelation with BAPTA-acetoxymethyl (AM) ester. In human embryonic kidney (HEK-293) cells, which constitutively express PARs, thrombin, PMA and FSK elevated AEA levels, and the effects of the two former compounds were counteracted by the PKC inhibitor, RO318220, whereas the effect of FSK was reduced by the PKA inhibitor RpcAMPs. In conclusion, we report that AEA levels are stimulated by both PKC, either directly or after thrombin receptor activation, and PKA, possibly in a way independent from intracellular calcium. Since AEA activates TRPV1, these findings may suggest the existence of an amplificatory cascades on this receptor in sensory neurons.