Effect of intense pulsed light on the expression of aquaporin 3 in rat skin

Intense pulsed light (IPL) technology has been popularly employed in clinical treatments for dermatological and cosmetic purposes in recent years; yet, the underlying mechanisms of its functions are not fully elucidated. On the other hand, aquaporin (AQP) 3, a member of a subgroup of the aquaporin family that transports both water and small solutes, such as glycerol, has been documented to play an important role in the skin homeostasis. We thus examined the possible involvement of AQP3 in the functional mechanisms of IPL irradiation. Rat dorsal skin areas were irradiated one to three times with IPL at doses of 15, 25, and 35 J/cm2. Skin specimens were collected 7 days after the final irradiation and analyzed for changes in histology, skin hydration, mRNA, and protein expressions of AQP3. IPL induced no significant variations in the mRNA expression levels. Twice or thrice irradiation at the dose of 25 or 35 J/cm2 significantly enhanced AQP3 protein expression. Immunofluorescence study revealed that AQP3 was mainly localized to keratinocyte membranes in the basal layer of epidermis, and the localization was unaltered by IPL. In addition, the pattern of IPL-induced changes in skin hydration was generally coincided with the expression profile of AQP3. These results suggest the possibility that one of the functional mechanisms of IPL might be related to the regulation of AQP3 protein expression.