Role of essential oils in antioxidant capacity and immunity in a rat model of mixed stress
Animal wellbeing is a balance between environmental stress and nutrition that regulates homeostasis. Augmentation of animal feed with essential oils can promote homeostasis. The present study was designed to observe the biochemical, immunological, and biological effects of daily administration of a mixture of essential oils (EOM) in a stressed rat model. Forty-eight adult male Sprague Dawley rats were randomly allocated to four groups, namely a control group (C), a stressed group (S), a treated group (Tr), and a stressed group that received the treatment (TrS). The treatment was applied by adding EOM to the water (0.2 ml/l) three days per week for 28 days. Two chronic stressors (isolation and crowding) were applied to animals in groups S and TrS. Total oxidant status (TOS) increased in the S group compared with C, whereas it decreased when fed with EOM. Although TOS was the same in S and C, it increased in Tr compared with C. There was a significant increase in interleukin 4 (IL-4) in S compared with C, and EOM reversed the IL-4 level. Nevertheless, an increase was seen in the weights of the liver, intestine, brain, and testes in TrS compared with S. The increase in water intake was a result of stress, but feeding with EOM decreased water consumption gradually. This study showed that 0.2 ml/l EOM had protective effects on antioxidant status, immunity and liver function, and decreased water consumption under stress conditions.