Changes in the hormonal function of the hypophysis-adrenal system by administration of cortisol in 'fixed' phases of the postnatal ontogenesis in rats

Administration of cortisol on the 13th, 15th, and 17th days of postnatal ontogenesis was shown to exert a long-lasting modifying effect upon the hypophysis-adrenal system's (HAS) stress reactivity in the rat litter. The effect involved a longer duration of hormonal response to immobilisation stress: a longer-lasting elevation of the corticosterone level in the blood plasma suggesting a diminished sensitivity of the HAS to feed-back signal. In hippocampus, frontal cortex and hypothalamus of the experimental rats, a decrease in receptor binding of labeled corticosterone was revealed.