Figure 1.

Timing of UV-induced responses. Both allodynia and hyperalgesia develop before overt morphological evidence of epidermal damage and cleaved caspase immunoreactivity indicative of programmed cell death. Although mild allodynia arises earlier than hyperalgesia, the peak response and subsequent diminishment of hyperalgesia occur more rapidly. Staining using a stress response reporter (msn-lacZ, which reads out activation of the Jun N-Terminal Kinase signaling pathway) was evident from 4 to 48 hours after UV treatment. Solid lines, times response was seen most often. Dashed lines, times response was occasionally observed, or was mild or diminishing.