Inhibitory effects of TRPV1 blocker on UV-induced responses in the hairless mice.

The transient receptor potential vanilloid 1 (TRPV1) channel can be activated by vanilloids, exposure to ultraviolet (UV) irradiation, heat, or protons, and conditions that occur during tissue injury. In the present study, we investigated whether or not TRPV1-specific blocker, 5'-iodoresiniferatoxin (I-RTX), can reduce UV-induced matrix metalloproteinases (MMPs), pro-inflammatory cytokines, cyclooxygenase (COX)-2, and p53 expression in the skin of hairless mice. Our results showed that I-RTX inhibited UV-induced skin thickening, as measured by a caliper, or in hematoxylin and eosin (H&E)-stained sections. UV-induced mRNA and protein expression of MMP-13, MMP-9, MMP-3, and MMP-2 was significantly reduced by I-RTX. We also observed the inhibitory effects of I-RTX on UV-induced mRNA expression of the pro-inflammatory cytokines, interleukin (IL)-1β, IL-2, IL-4, and tumor necrosis factor-α. UV-induced COX-2 and p53 protein expression was also significantly decreased by I-RTX. From the above results, we suggest that TRPV1-specific blocker, I-RTX, could prevent UV-induced skin responses, and provide new insight into development of effective therapeutic methods for photoaging.