Induction of Ornithine Decarboxylase Activity in Hairless Rat Epidermis as a Pharmacological Model: Validation of the Animal Model

The study used hairless Sprague Dawley rats to assess the ability of retinoids to inhibit epidermal ornithine decarboxylase activity induced by sellotape stripping. A total of 100 rats (50 males and 50 females) aged 4 to 11 weeks were examined to validate the model. The study found that hair growth occurred at 6-7 weeks and 10-11 weeks, with more pronounced growth in males. No histological changes were observed in the stratum corneum, but an increase in epidermal thickness was noted in 9-week-old males. Sellotape stripping was more effective and consistent in females, with lower individual variation (5%-10% in females vs. 10%-20% in males). The research concluded that female rats aged about 8 weeks provided the most reproducible response and ease of use for this model.