LONG-TERM EFFECTS OF NEONATAL MATERNAL-DEPRIVATION AND ACTH ON HIPPOCAMPAL MINERALOCORTICOID AND GLUCOCORTICOID RECEPTORS

In the brain, corticosteroids bind to two types of receptors, the clas sical glucocorticoid receptor (GR) and the mineralocorticoid receptor (MR). The effects of different manipulations taking place during early ontogeny on GR and MR binding properties were examined in the adult h ippocampus. Infant rats at postnatal day (pnd) 3 were deprived of mate rnal contact for 24 h and injected with saline or ACTH(1-24) at the en d of the deprivation period. They were then returned to their dams and weaned on pnd 21. At pnd 48, they were sacrificed (24 h post adrenade ctomy) and the hippocampal MR and GR measured using an in vitro cytoso l binding assay. In the male rats, deprivation an deprivation + ACTH r esulted in an reduction of GRs. MRs were also significantly down regul ated in the deprived males. In the female rats, saline injections in d eprived female rats resulted in increased GR capacity and ACTH injecti ons led to a further up-regulation of the GRs. None of the early manip ulations influenced the regulation of the MRs in females. The binding affinity for corticosteriod receptors was also altered by some of the early manipulations. These results in adult (7-week old) rats indicate that the receptor systems for corticosteroids in the brain are sensit ive to brief manipulations occurring early in development. These chang es in receptor capacity and/or affinity may affect corticosteroid-medi ated processes in the adult rat.