Serum Levels of Cortisol and Testosterone in American Mink (Neogale Vison) Selected for Aggressive and Tame Behavior towards Humans

Several molecules, including glucocorticoids (cortisol, corticosterone,etc.) and testosterone in mammals, are thought to be associatedwith tame/aggressive behaviour towards humans, but these relationshipsremain controversial. The American mink (Neogalevison) represents a model in the studies of physiologicaltraits in aggressive and tame behavioral phenotypes. Given the seasonalityin reproduction, fur moulting, and hormonal levels during the lifecycle of mink and the reciprocal relationships between the hypothalamic–pituitary–adrenaland hypothalamic–pituitary–gonadal axis, it is necessary to studythe levels of cortisol and testosterone in the behavioral phenotypesof the animals in various seasons. Of particular interest is theperiod after the breeding season (late March—early April), whenthe level of androgens decreases. The aim of the study was to characterizethe neuroendocrine physiological phenotypes associated with aggressiveand tame behaviors by measuring the levels of cortisol (basal level)and testosterone in the blood serum of American mink at the endof the breeding season. Blood samples were taken from animals selectivelybred for tame and aggressive defensive reaction towards humans atthe Institute of Cytology and Genetics in Novosibirsk, Russia. No differenceswere found in serum levels of cortisol and testosterone betweenaggressive and tame mink. We found a significant negative relationshipbetween the studied hormones in tame mink. Thus, selection of Americanmink for either aggressive or emotionally positive responses tohumans does not appear to be associated with changes in the levelsof the hormones studied at the end of the breeding season.