Age and androgen-related changes in morphological parameters, haematological indices and serum protein fraction in common vole (Microtus arvalis Pall.) growing in different photoperiods.

In male voles raised under different light conditions (L:D = 24:0, L:D = 18:6, L:D = 6:18) the following results were obtained. In the young males erythropoiesis seemed to be greatest in voles growing in "winter" photoperiod. In this light condition RBC count showed a tendency to decrease with age while in other illuminations erythrocyte numbers increased. The age related changes in RBC count were very similar to those observed in common voles aging in the different natural seasonal generations. The androgen level was higher after birth and then decreased. After reaching sexual maturity (13-15 weeks of vole life) it showed a peak and then decreased progressively. The age related changes in alpha 2-globulins (considered to be a potential binding proteins for steroid hormones) and in androgen level suggested a regulating mechanism based on a balance of hormones--blood proteins. The correlations stated between androgens and the parameters studied indicated more steroid than age-related metabolic changes. The more androgens, the less beta-globulin and fibrinogen while the greater rate of body and testes weight, as well as of albumin level and of RBC count were observed. All those might affect the transmission of lipoproteins from blood to adipose tissue and less predisposition to fighting with potentially lower blood coagulation capacity and more effective anabolic (erythropoietic) processes in the more "androgenic", reproductively active male voles. A higher protein metabolism in constant light, i.e. the higher level of the majority of plasma protein fraction and small weight was suggested. The high level of androgens in "winter" photoperiod might condition the aggressiveness and prevent hibernation in natural winter conditions.