Minimum Erythematous Dose Assay: A Method for Measuring UV Sensitivity in Mouse Models

- Melanocytes produce a dark pigment called eumelanin that absorbs harmful UV radiations, protecting the skin. To measure UV sensitivity, begin by taking an anesthetized mouse model. Prep the mouse by removing its dorsal fur to expose the epidermal layer. Fasten a piece of UV-blocking tape bearing a set number of holes on the exposed skin. Fix small detachable tapes over all the holes, except one, to mask the opening.

Now, subject the mouse to UV radiation for the desired time duration. During the exposure period, unmask the remaining holes sequentially at predetermined time points. This facilitates the successively exposed skin patches to receive decreasing doses of UV radiation. The holes allow the localized penetration of UV rays into the mouse's epidermis.

Upon exposure, the epidermal cells release pro-inflammatory molecules. These molecules diffuse towards the dermis and dilate the dermal blood vessels causing erythema or skin redness. Subsequently, the leukocytes infiltrate the dermis and cause edema or swelling in the exposed area.

At the experimental endpoint, stop the radiation and remove the tape to observe erythema and edema. In the following protocol, we will measure UV