Plasma β-Endorphin Concentrations During Natural and Artificially Induced Winter Hair Growth in Mink (Mustela Vison)

The study investigated the role of plasma β-endorphin and ACTH in the initiation of winter hair growth (anagen) in mink. Treatments with melatonin (MEL) or bilateral adrenalectomy (ADX) induced early anagen, but plasma β-endorphin levels did not change during natural anagen onset. ADX increased β-endorphin levels, but supplementation with cortisol (CORT) delayed anagen. MEL-induced anagen was not mediated by β-endorphin/ACTH, and CORT inhibited anagen through direct skin effects. The study suggested that local production of ACTH and β-endorphin in the skin might be necessary for anagen induction. Further research was planned to explore MEL binding sites and POMC expression in mink skin.