The metabolic-oxidative activity of different nervous and glandular structures (amygdala, hypothalamus, lateral-frontal cerebral cortex, adrenal glands) in male and female rats under acute stress caused by physical immobilization, was determined. The sexual cycle of the female rat was controlled by examination of their vaginal frotis. One experimental group during estrus and another one during diestrus were selected. At the same time ovariectomy was performed on an experimental group in order to eliminate the hormonal influences of the ovary. Results show there are no significant differerneces in the oxidative metabolism. Nor in the numbers of ulcers. Hypothalamus-hypophyseal-adrenocortical activation was made manifest on obtaining significant differences in the weight of the adrenal glands, a fact long ago reported in a number of studies. Necropsy showed severe gastric hemorrhages and ulcer in the stomach. Nevertheless, no significant differences between the distinc experimental groups were obtained. The likely participation of sexual hormones in female rats is discussed in the light of our results.