Effects of phytoncides on spontaneous activities and sympathetic stress responses in Wistar Kyoto and stroke-prone spontaneously hypertensive rats

Phytoncides are volatile substances mainly released from trees that have been reported to reduce the cardiovascular response to restraint stress in stroke-prone spontaneously hypertensive rats (SHRSP). To clarify the more general effects, we examined the effects of phytoncides on spontaneous activities without stress and on sympathetic responses to cold and restraint stress in SHRSP and Wistar-Kyoto rats (WKY). When exposed to phytoncides, spontaneous activity was decreased both in WKY and SHRSP. The cold
stress-induced increase in urine adrenaline and nora-drenaline amounts was not affected by phytoncides. Under restraint stress, both in WKY and SHRSP, heart rate and blood pressure tended to be lower, and the plasma concentration of cathecholamines was
lower in the phytoncides group than in the control. These results suggest that phytoncides decrease spontaneous activity as well as cardiovascular responses to
restraint stress but not to cold stress in both WKY and SHRSP.