Age-Related Changes in the Dorsal Skin Histology in Mini and Wistar Rats

The study examined age-related changes in the dorsal skin histology of Mini rats (MRs) and Wistar rats (WRs), focusing on the impact of growth hormone (GH) deficiency. MRs, which had reduced plasma GH levels, exhibited thinner skin with less collagen, more subcutaneous adipose tissue, and smaller sebaceous glands compared to WRs. Notably, the hair cycle differed significantly between the strains; MRs entered a prolonged telogen phase after two 4-week cycles, while WRs continued to a third cycle. The lower serum insulin-like growth factor (IGF)-1 levels in MRs might have contributed to these differences, despite similar IGF-1 and IGF-1 receptor mRNA levels in the skin. MRs were considered a valuable model for studying dermatopathy related to GH deficiency and understanding GH's effects on skin and hair follicle development.