Protein Malnutrition Disrupts Skin Histomorphometry and Dermal Fibrocollagen Deposition in Wistar Rats

Abstract

Protein malnutrition compromises tissue growth and repair, but quantitative evidence describing its effects across multiple structural compartments of the skin remains limited. This study evaluated skin histomorphometry and dermal fibrocollagen deposition in male Wistar rats exposed to a 5% protein diet for eight weeks. Ten rats were allocated to a normal control group and a protein-malnutrition group (n = 5 each). Skin sections were stained with hematoxylin and eosin to measure epidermal, dermal, and subcutaneous fat thickness and to count hair-follicle profiles per unit sectional area. Sirius Red staining and ImageJ analysis were used to quantify the proportion of dermal fibrocollagen. Protein malnutrition significantly reduced epidermal thickness from 25.04 ± 3.17 to 15.00 ± 2.76 µm (40.1%; p = 0.0007), dermal thickness from 624.16 ± 50.66 to 470.29 ± 50.26 µm (24.7%; p = 0.0013), subcutaneous fat thickness from 193.98 ± 25.53 to 47.46 ± 16.53 µm (75.5%; p < 0.0001), and hair-follicle profiles from 66.40 ± 8.17 to 38.80 ± 10.55 per unit area (41.6%; p = 0.0018). Dermal fibrocollagen area decreased from 56.88 ± 2.45% to 39.69 ± 5.24% (30.23%; p < 0.001). Histological observations corroborated thinning of the epidermis and dermis, loss of subcutaneous adipose tissue, reduced follicular profiles, and sparse, disorganized collagen bundles. These findings demonstrate that prolonged protein restriction disrupts the integrated architecture of the skin, with the largest proportional loss occurring in subcutaneous fat, and support skin histomorphometry as a sensitive indicator of protein-malnutrition-related tissue deterioration.