Rat skin physiology is modified by age

Animal models have been useful in the study of specific mechanisms affecting human skin. Such is the case with ageing and the micromechanical changes determining wrinkles in UVirradiated mice. These models enabled us to understand that ageing encompasses many peculiar mechanical responses which cannot be explained by homogeneous deformation of the skin. Moreover, a major aspect to consider is that ageing processes differ among species and direct inferences are rarely possible. This project aimed to compare age-induced changes in skin properties by studying two Wistar rat groups of different ages – young adult rats (n=7, 20–24 week-old) and old adult rats (n=5, 48–72 week-old). Non-invasive measuring approaches involving transepidermal water loss (TEWL), superficial hydration (MoistureMeter), and biomechanics (Reviscometer, and Cutometer by MPA80) were taken in the animal dorsum (neck, bottom) over a period of five days, allowing statistical comparisons between groups. Results revealed no significant differences for TEWL, firmness or viscoelasticity between the two groups. However, a significant hydration decrease, of nearly 40%, was noted in the old adult rats group. These results, although preliminary, if translatable to humans could be useful to address age-related changes in processes such as healing, or patch dressing efficacy/safety where hydration is a critical determinant. Their potential use for the prediction of efficacy and or safety of topically applied products for the elderly as compared to young adults may warrant further investigation..