The histomorphometric and histopathologic effect of methionine on the epidermis and dermis layers of skin in rat

The skin is the largest organ of the body and is composed of epidermis (the outermost layer of cells consisting mainly of keratinized, stratified, squamous epithelium) and dermis (a layer of connective tissue composed of cells and fibrils such as collagen bundles). The aim of this study was to assess the effect of excess methionine on the histomorphology and histomorphometry of collagen bundles in these layers. Eighty, 9–10-week old, male rats were randomly allocated into eight equal groups. Each group received one of the following treatments: L-methionine (50, 100 or 200 mg/kg B.W.), vitamin C (50 mg/kg B.W), combination of L-methionine (all 3 concentrations) and vitamin C (Met + Vit C), or normal saline as control (CT) for 20 consecutive days. After terminating the animals on day 21, skin samples were taken, and the epidermis, papillary, and reticular layers were evaluated histologically. The data obtained revealed that methionine does not increase collagen bundle thickness unless combined with vitamin C. We suggest that lack of crosslinking occurs when using methionine alone. The greatest increase in both epidermis and dermis occurred in the Met 100 + Vit C group. There was no significant difference between Vit C and control groups. Histopathology did not show any congestion or inflammatory cell infiltration in any treatment groups compared to the controls.