Table 3.

Overall contribution of TRPV1, TRPA1 and TRPC5 to metabolic syndrome: a summary of endogenous agonists, expression sites and roles.

TRP Channel	Endogenous Agonists	Expression Site	Role in MS
TRPV1	12 (S)-HPETE [118], 20-HETE [119], 9-HODE and 13-HODE [120], anandamide [121], H2S [122], ROS (H2O2) [123]	Adipose tissue/adipocytes [124,125,200,201], liver [126,127], M1 macrophages [128], pancreatic β-cells/langerhans islets [132], coronary endothelial cells [123], T cells [129,130,131], skeletal muscle [202,203,204], pro-opiomelanocortin neurones [205]	Increase of insulin sensitivity [216,220,221], browning of WAT, reduction of lipid synthesis and obesity/adiposity [201,203,204,239], enhanced thermogenesis [240] and leptin sensitivity [219], reduction of lipid accumulation and TG [127], protection against endothelial dysfunction [253], increase of GLP-1 and attenuation of ghrelin production [278]
TRPA1	Methylglyoxal [138], 4-HNE, 15-deoxy-delta(12,14)-prosta-glandin J2 (15d-PGJ2) and H2O2 [139]	Pancreatic β-cells/langerhans islets [137,206], T cells [175,176,177], adipocytes [244,245], vagus nerve [246]	Macrophage-mediate responses in atherosclerosis [180,184], increase of insulin secretion [137,222,223,224,225] and sensitivity [228,258,259], reduction of insulin signalling and insulin-induced glucose uptake in skeletal muscle cells [229], weight loss and reduction of TG and cholesterol [244,247], attenuated adipogenesis [250], increased adipose tissue inflammation and ROS [248,250] reduction of ghrelin [282], production of ghrelin [288]
TRPC5	H2O2 [145], reduced TRX [146], and fatty acids [147]	Endothelial cells [166], T cells [185], M1 macrophages [186], pancreas [208], adipose tissue [147,200], pro-opiomelanocortin neurones [209,210,211]	Polarization of macrophages to M2 and protection against atherosclerosis [186], negative regulation of adiponectin [147], enhance of energy expenditure [209,298]