Partial Changes in Coat Color from Yellow to Black in Genetically Obese YellowAyMice after Removal of Submandibular Glands

Abstract

Abstract The submandibular glands (SMGs) were removed in male genetically obese yellow Ay mice at 24 weeks of age. The mice lost weight postoperatively unlike the sham-operated controls. Furthermore, the coat color changed after sialoadenectmy from yellow to black on part of the back. The pattern and tone of the black regions varied from mouse to mouse. The black color was conspicuous 4 to 8 weeks postoperatively, then gradually faded, but was still noticeable for at least 5 months. In Ay mice, the agouti gene is overexpressed, and the pleiotropic effects of excess agouti protein are believed responsible for their obesity and yellow coat color; agouti antagonizes both the hypothalamic melanocortin-4 receptor responsible for obesity and the skin melanocortin-1 receptor responsible for yellow pigmentation. Our observations suggest that a factor or factors in the SMG are essential for the expression of two separable phenotypes. The SMG presumably affects the expression level or action or both of agouti to al...