Attenuation of stress-induced elevations in plasma ACTH level and body temperature in rats by green odor

To investigate the effect of green odor on the elevation of the plasma adrenocorticotropic hormone (ACTH) levels and body temperature (T(b)) induced by stress, adult male rats were subjected to a 2-h immobilization stress and exposed to green odor or its vehicle only. In comparison with the vehicle group, animals in the green odor group showed a significant reduction in plasma ACTH levels at the end of the stress when green odor was applied during the stress. The elevated plasma ACTH levels 2 days after the stress were reduced by green odor applied 0, 1, 2, 4 or 6 h after the beginning of the stress. Neither the immediate nor the long-lasting plasma ACTH response was affected by a prestress treatment of green odor. T(b) elevation was evident following the end of the stress and during the light phase the day after the stress. Both the immediate and the long-lasting elevations in T(b) were attenuated by green odor. These data suggest that green odor extracted from green leaves has a relieving effect on plasma ACTH and T(b) levels induced by an immobilization stress for not only immediate but also long-lasting periods.