Studies on the role of ACTH and of 5-HT in anxiety, using an animal model

Abstract

Abstract The effects of ACTH (5 & 7·5 μg/100 g) were studied using a new animal model of anxiety. ACTH had an anxiogenic effect that was maximal during a 10 min test period starting 3 min after injection. The behavioural effects of ACTH were counteracted by chronic administration of chlordiazepoxide (5 mg kg−1 for 5 days) and by acute administration of ethanol (0·4 g kg−1). These anxiolytic drugs decreased the turnover of 5-HT in the midbrain, hypothalamus and cerebral cortex, whereas ACTH increased 5-HT turnover in the midbrain and hypothalamus. It is therefore proposed that anxiety results from the action of ACTH, possibly on 5-HT pathways in the midbrain and hypothalamus.