Table 1.

TRPs in TMJD pain.

	Localization in relevant tissues	Dysregulation in relevant tissues	Pain regulation
TRPV1	TG neurons innervating the TMJ, masseter muscle, synovial lining cells of joint of rats [17, 18, 20, 21] Synovial tissues of human TMJ [19]	Upregulated in cultured rat synoviocytes by LPS [24], in rat TG and hippocampus after CFA injection into TMJ [25, 26], and in TG after CFA injection into rat masseter muscle [28] or mouse TMJ [22] Unchanged in amygdala, prefrontal cortex, and thalamus after CFA injection into rat TMJ [25]	Capsaicin injection into the masseter muscle causes pain in rats [20] or human [29] Inhibition or knockout of TRPV1 attenuates mechanical hyperalgesia, spontaneous pain, and bite force reduction-caused by CFA injection into masseter muscle in rats [28, 31, 32] Ablation of TRPV1-expressing TG afferents attenuates spontaneous pain and bite force reduction-caused by CFA injection into masseter muscle in rats [32] Inhibition of TRPV1 in hippocampus attenuates mechanical allodynia-caused by CFA injection into TMJ [25] or masseter muscle [26] in rats
TRPV4	TG neurons innervating mouse TMJ [22] and fibroblast-like synoviocytes of rat TMJ [23]	Upregulated in TG neurons after CFA injection into mouse TMJ [22] Downregulated in TG neurons after CFA injection into rat masseter muscle [28]	Intraarticular injection of TRPV4 agonists into TMJ causes mechanical allodynia in rats [23] Inhibition or knockout of TRPV4 attenuates bite force reduction-caused by CFA injection into mouse TMJ [22]
TRPA1	TG neurons innervating masseter muscle of rats [20]	Upregulated in astrocytes of trigeminal caudal nucleus after CFA injection into rat TMJ [27] and in TG after CFA injection into mouse TMJ [22] or rat masseter muscle [28]	Mustard oil injection into the masseter muscle causes nocifensive pain and mechanical hyperalgesia in rats [20] Inhibition of TRPA1 attenuates mechanical hyperalgesia caused by CFA injection into masseter muscle in rats [30] Inhibition or knockout of TRPA1 attenuates spontaneous pain-caused by CFA injection into masseter muscle in rats [31] Inhibition of TRPA1 does not attenuate bite force reduction-caused by CFA injection into masseter muscle in rats [31]
Other TRPs	TRPV2, TRPV3, TRPM2, TRPM3, TRPM8 in mouse TG [22] TRPV2, TRPV3, TRPM2, TRPM3, TRPM8, TRPC3, TRPC4, TRPC6, and TRPC7 in mouse or rat TG [28]	TRPM3 and TRPM8 are upregulated, but TRPV2, TRPV3, TRPM2, TRPC3, TRPC4, TRPC6 and TRPC7 remained unchanged in TG after CFA injection into rat masseter muscle [28] TRPM3 and TRPM8 remain unchanged in TG after CFA injection into mouse TMJ [22]	Unknown