Influences of peripheral adrenocorticotropin 1-39 (ACTH) and human corticotropin releasing hormone (h-CRH) on human auditory evoked potentials (AEP).

Hormones of the hypothalamus-pituitary-adrenal (HPA) axis have been considered to form part of an efferent humoral system modulating central nervous stimulus processing. The present experiments were designed to compare the effects of iv bolus administrations of placebo, porcine ACTH 1-39 (1.5 U) and h-CRH (25 micrograms) on auditory evoked potentials (AEPs) in healthy men. Also, cardiovascular parameters, cortisol and self-reported mood were assessed. ACTH significantly reduced the amplitude of the N1 component of the AEP; P1 and P2 remained unchanged. The selective reduction of N1 amplitude defies an interpretation of the changes in terms of a reduced stimulus-induced cortical arousal following ACTH; the ACTH-induced changes may rather indicate an influence on frontocortical functions of directing attention. The effect of ACTH on N1 cannot be attributed to its adrenocorticotropic action or to cardiovascular changes, but appears to represent an intrinsic extraadrenal influence of the hormone. The data do not provide evidence for effects of h-CRH on central nervous stimulus processing in humans, after peripheral administration.