Brain corticosteroid receptors are regulated by neural control as well as by adrenal hormones. In this study we tested the effect of septo-hippocampal cholinergic lesions on the binding capacity of corticosteroid receptors. Rats were injected with ibotenic acid into the medial septum, and hippocampal type I and type II, and hypothalamic type II corticosteroid receptors were measured 15 days later. In lesioned animals the number of type I corticosteroid receptors in the hippocampus was increased and their affinity decreased. In the hypothalamus only an increase of type II corticosteroid receptors was observed. As expected, lesioned rats showed an increase in basal plasma corticosterone levels.