Endocrine Abstracts

Captive breeding of wild animals is a first step of domestication. The process is accompanied by a number of adaptations to captive conditions, which resulting in behaviour, physiological and morphological changes. One of morphological consequences of domestication is a coat-colour mutation named Star (S) that is characterised by some unpigmented areas on the skin. The dominant mutation was first revealed in farm-bred populations of silver foxes, but the highest frequency of this mutation was observed in silver foxes selected artificially for domestic behavior (nonaggression to human). The aim of the present work was to investigate effects of Star gene on hormonal activity of the ovaries and adrenals, and fertility in adult silver foxes selected for domestic behaviour (n=38) and unselected control (n=37). At 22–28 days of pregnancy and during midanoestrus, the homozygous (SS), heterozygous (Ss) and wild-type (ss) females from selected and unselected populations were euthanized, blood samples were taken, gonads and adrenals were dissected. Plasma levels of progesterone, oestradiol and cortisol, as well as gonadal content of progesterone and oestradiol, and adrenal content of cortisol and progesterone were measured by RIA. Fertility was estimated by the number of corpora lutea and implantation sites in the same groups. The Star allele decreased plasma concentrations of progesterone and cortisol, ovarian progesterone contents and adrenal contents of both hormones during pregnancy with a most pronounced effect in selected groups. We also showed negative effects of this gene on the number of corpora lutea and implantation sites in selected groups, and on ovarian and adrenal weights in both behavioural groups. In conclusion, our results indicate that in addition to its effect on pigmentation, the S allele also causes a number of endocrine pleiotropic effects, which are more expressed in animals selected for domestic behaviour.