Through specific cytoplasmic-nuclear receptors, brain appears as a target tissue for corticosteroids in their affecting neuroendocrine and behavioural activities. 3H-corticosterone (3H-B) uptake in various brain areas of differentially reared mice was studied in order to ascertain possible differences which might be connected to the different patterns of behavioural, neurochemical and stress responses. In 4-day adrenalectomized mice 1-h 3H-B uptake was higher in grouped than in isolated ones. Prlonged social stress in the grouped mice before adrenalectomy remarkably reduced 3H-B uptake. In 4-hour adrenalectomized dominant males, 4-h 3H-B uptake was higher than in submissive ones. All drugs tested (chlorpromazine, fluanisone, morphine, methergoline, naloxone, propranolol) affected 3H-B uptake. Knowledge of the interactions between behavioural manipulations or drugs and brain corticosteroid-receptors can improve the approach to the regulatory mechanisms of the hypothalamo-hypophyso-adrenal axis also in relation with behavioural phenomena.