The One-Locus Silver-Blue Fur Color Mutation (pp) in Minks Affects the Dopamine System of the Brain

The features of dopamine metabolism and dopamine receptors in the brain of homozygous silver- blue (pp) minks were examined in comparison with wild-type (PP) minks. A pp mutation was found to affect the dopamine turnover in corpus striatum, which is one of the major dopaminergic brain structures. In silver- blue minks, increased dopamine catabolic enzyme activity of monoamine oxidase type B (MAO B), together with the decreased level of dopamine and the tendency for the level of the metabolite 3,4-dihydrophenilacetic acid to increase, were demonstrated in this brain region. No significant alterations in the level of another dopamine metabolite, homovanillic acid or in D1 and D2 receptor density were shown. In the midbrain and hippocampus, an elevated level of MAO B activity was detected. We found no modifications in receptor properties, nor in dopamine turnover in a mesolimbic dopamine structure, the nucleus accumbens. We propose that the primary effect of pp mutation is an increase in MAO B activity resulting in dopamine turnover alterations and probably in dopamine-dependent behavior (pleiotropic cascade).