Agouti-related maturation and tissue distribution of alpha-Melanocyte Stimulating Hormone in wild-type (AwJ/AwJ) and mutant (Ay/a,a/a) mice.

Because of ectopic overproduction of agouti protein, yellow alleles (A(y) and A(vy)) of the murine agouti gene may secondarily modulate the synthesis, maturation (i.e., acetylation), and/or tissue deployment of alpha-Melanocyte Stimulating Hormone (MSH). We used HPLC to test the hypothesis that A(y)/a mice exhibit altered concentrations of desacetyl-, monoacetyl-, and diacetyl-alpha-MSH in pituitaries, sera, and telogen hair bulbs when compared to black (a/a) mice. We also used RIA to measure total MSH in those same tissues of A(y)a,a/a, and white-bellied agouti (A(wJ)/A(wJ)) mice (Strain C57BL/6J). We found no evidence that A(y)/a mice possessed an imbalance of des-, mono-, and diacetylated alpha-MSH species. However, radioimmunoassay (RIA) analyses of total MSH suggest that wild-type agouti mice (A(wJ)/A(wJ)) exhibited significantly decreased (P < 0.05) tissue levels of total alpha-MSH in pituitaries, sera, and regenerating hair bulbs when compared to those of mutant A(y)/a and a/a mice.