4.8. Treatment of TPA-Induced Psoriasis-Like Skin Inflammation in C57BL/6J Mice

Eight-week-old female C57BL/6J mice (20–25 g) were obtained from and housed at the Experimental Animal Center of Guangzhou University of Traditional Chinese Medicine. Studies were performed in accordance with the guidelines approved by the Animal Ethics Committee of Guangzhou University of Traditional Chinese Medicine (approval number: S2017093). All mice were housed in a specific pathogen-free facility with food and water ad libitum.

Forty-eight mice were randomly assigned into eight groups, including the control group, model group, and six treatment groups (treated with the high or low dose of C1, C2, or C3, respectively). Animals in the model and treatment groups received 20 μg TPA (Sigma, USA) in 200 μL acetone by topical application to their shaved backs on days 0 and 3, while animals in the control group received only 200 μL acetone.

In the treatment groups, 60 mg of each prepared compound-containing ointment was topically administered to the dorsal skin twice a day for seven consecutive days, while Vaseline-only ointment was similarly administered to the control group as the vehicle control. On days 0 and 3, ointments were given 30 min after TPA treatment. On day 8, all animals were euthanized by cervical dislocation and the TPA/compound-treated dorsal skin samples were harvested. Half of each skin sample was fixed in 10% neutral buffered formalin for histological analysis, while the other half was snap-frozen in liquid nitrogen and stored at 80 °C for mRNA expression studies. The samples were homogenized, and mRNA was extracted and quantified as described previously.