Coat Color in Intact and Neurointermediate Lobe-Grafted Agouti Mice: Effect of Dopamine Agonists and Antagonists

The study observed coat color changes in agouti C3H Avy mice over the first 6 months of life, identifying three stages: yellow at birth, dark-gray from the 8th week to 6 months, and yellow again after 6 months. Researchers investigated the role of the pituitary pars intermedia in these changes by administering dopamine antagonists, pimozide or d-butaclamol, which darkened the coat color in both newborn and adult mice. Grafting the pituitary pars intermedia in adult mice also darkened the coat, while dopaminergic agonists prevented this effect. The study suggested that pars intermedia peptides influenced the hair color cycle, regulated by a dopaminergic mechanism from early life.