Expression of Cyclooxygenase Isozymes During Morphogenesis and Cycling of Pelage Hair Follicles in Mouse Skin: Precocious Onset of the First Catagen Phase and Alopecia Upon Cyclooxygenase-2 Overexpression

The study explored the expression of cyclooxygenase (COX) isozymes, particularly COX-2, during hair follicle development and cycling in mice. Overexpression of COX-2 in transgenic mice led to an early onset of the catagen phase and alopecia, characterized by sparse hair and hairless areas, due to elevated prostaglandin E2 (PGE2) levels and sebaceous gland hyperplasia. This disrupted normal hair follicle cycling, with more catagen follicles compared to wild-type mice. Treatment with the COX-2 inhibitor valdecoxib normalized PGE2 levels and prevented alopecia, indicating COX-2's crucial role in hair growth abnormalities and its potential as a target for hair loss treatments.