Acetylcholine inhibits hypoxia-induced tumor necrosis factor-α production via regulation of MAPKs phosphorylation in cardiomyocytes.
Recent findings have reported that up-regulation of tumor necrosis factor-alpha (TNF-α) induced by myocardial hypoxia aggravates cardiomyocyte injury. Acetylcholine (ACh), the principle vagal neurotransmitter, protects cardiomyocytes against hypoxia by inhibiting apoptosis. However, it is still unclear whether ACh regulates TNF-α production in cardiomyocytes after hypoxia. The concentration of extracellular TNF-α was increased in a time-dependent manner during hypoxia. Furthermore, ACh treatment also inhibited hypoxia-induced TNF-α mRNA and protein expression, caspase-3 activation, cell death and the production of reactive oxygen species (ROS) in cardiomyocytes. ACh treatment prevented the hypoxia-induced increase in p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK) phosphorylation, and increased extracellular signal-regulated kinase (ERK) phosphorylation. Co-treatment with atropine, a non-selective muscarinic acetylcholine receptor antagonist, or methoctramine, a selective type-2 muscarinic acetylcholine (M(2) ) receptor antagonist, abrogated the effects of ACh treatment in hypoxic cardiomyocytes. Co-treatment with hexamethonium, a non-selective nicotinic receptor antagonist, and methyllycaconitine, a selective alpha7-nicotinic acetylcholine receptor antagonist, had no effect on ACh-treated hypoxic cardiomyocytes. In conclusion, these results demonstrate that ACh activates the M(2) receptor, leading to regulation of MAPKs phosphorylation and, subsequently, down-regulation of TNF-α production. We have identified a novel pathway by which ACh mediates cardioprotection against hypoxic injury in cardiomyocytes.
Li
Dong-Ling
DL
Department of Pharmacology, College of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi, China.
Liu
Jin-Jun
JJ
Liu
Bing-Hang
BH
Hu
Hao
H
Sun
Lei
L
Miao
Yi
Y
Xu
Hai-Fei
HF
Yu
Xiao-Jiang
XJ
Ma
Xin
X
Ren
Jun
J
Zang
Wei-Jin
WJ
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D015687:Cell Hypoxia / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology*; D010766:Phosphorylation / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D043585:Receptor, Muscarinic M2 / Q000378:metabolism; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis* / Q000235:genetics
D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D043585:Receptor, Muscarinic M2; D014409:Tumor Necrosis Factor-alpha; D020928:Mitogen-Activated Protein Kinases; D053148:Caspase 3; D000109:Acetylcholine