Effects of Impairments to Glucocorticoid Receptor Mechanisms in Early Ontogeny on the Activity of the Hypophyseal-Adrenocortical System and Behavior in Male Rats.

The effects of treatment of rats with hydrocortisone (1 mg/100 g) or the glucocorticoid receptor blocker RU38486 (1 mg/100 g) from day 1 to day 5 of life on changes in the dynamics of the stress response of the hypophyseal-adrenocortical system (HAS), orientational-investigative activity, and anxiety in immature and adult male rats were studied. Excess glucocorticoid hormones during the early neonatal period was found to increase orientational-investigative activity and the level of anxiety in immature males without altering the functional activity of the HAS or behavior in adult rats. Conversely, impairment of glucocorticoid receptor mechanisms in brain structures in neonatal rats led to decreased feedback efficiency in the regulation of the HAS, decreases in motor activity, and increases in anxiety levels in conditions of contextual novelty, which was most clearly apparent at adult age. It is suggested that rearrangement of glucocorticoid reception during the neonatal period of development is among the causes of the various hormonal and behavioral impairments in adult individuals. [ABSTRACT FROM AUTHOR]