Emotional stress induces sex-specific sympatho-adrenomedullary responses in lambs

English. The aim of the study was to compare the effects of emotional stress measured by the plasma levels of catecholamines and cortisol in male and female lambs. Three-months-old lambs were stressed by 30 minutes of isolation from the herd. Stressed animals were separated individually in special room without acoustic and visual contact with each other, control animals stayed with the herd. Blood was taken by venipuncture (jugular vein) from all animals 10 min before the start of experiment and 10, 20, 30 and 60 minutes after the beginning of isolation. Plasma levels of cortisol and catecholamines-adrenaline, noradrenaline and dopamine were estimated by radioimmunoassay using commercial kits. Additionally, AUCs (areas under curve) were calculated for each parameter. The obtained results clearly showed significant differences in male (rams) and female (ewes) lambs responses to emotional stress. Plasma level of cortisol was much higher in females during the stress (P<0.01) than in males, similar pattern of stress response was observed in plasma dopamine level. In contrast, plasma levels of adrenaline and noradrenaline were significantly higher in males than in females (P<0.05). Therefore, the emotional stress induced sex-specific stress responses of sympathetic and adrenomedullary systems in growing lambs.

English. catecholamines, cortisol, stress, lamb, isolation

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