Effects of Royal Jelly on hypothalamic-pituitary-adrenal activity in adult male rats under unpredictable chronic stress

Chronic exposure to stress is often associated with increased activity of the hypothalamic-pituitary-adrenal axis (HPA) and causes chronic high plasma glucocorticoids concentrations, which can result in various diseases. Regading the fact that antioxidant agents can modulate the activity of the HPA axis, in the present study, the effect of royal jelly was investigated on the activity of the HPA axis in male rats under chronic unpredictable stress.

In the current experimental study, 24 adult rats were randomly divided into the following three groups: without stress-solvent, without stress- royal jelly, and with stress-solvent and with stress-royal jelly. The animals in the stress groups were exposed to chronic unpredictable stress for four weeks and received royal jelly or solvent during this time. The weight of the animals was measured and blood samples were obtained to determine the plasma concentration of corticosterone. Finally, the adrenal glands of the animals were removed and weighed.

The weights of the stressed rats (195.88±4.24) were lower than those of the non-stressed rats (231.13±5.91) (P<0.001). However, plasma corticosterone concentration (1.22±0.03) (P<0.01) and adrenal gland weights (51.85±2.49) (P<0.05) increased in the stress group, whereas Royal jelly decreased plasma corticosterone concentration and increased body weight in the stressed rats so that these values were close to the control group values. The use of this substance had no effect on adrenal gland weight.

It seems that Royal Jelly prevents the increase of plasma corticosterone concentration following exposure to chronic unpredictable stress. With regard to the fact that this substance has no effect on the weight of the adrenal glands, it has probably exerted its modifying effect on corticosterone by reducing the secretion of corticosterone from the adrenal glands.