Plasma corticosterone levels in the control, physical stress with vehicle (PS-V) group, PS with Valerian officinalis extract (PS-VE) group, psychological stress with vehicle (PCS-V) group, and PCS with VE (PCS-VE) group ( n = 7 per group; a
P < 0.05, indicating a significant difference compared to the control group; b
P < 0.05, significantly different from the PS-V vs. PS-VE or PCS-V vs. PCS-VE group; c
P < 0.05, significantly different from the PS-V vs. PCS-V or PS-VE vs. PCS-VE group). Error bars indicate SEM.