Effect of adrenocorticotrophic hormone on sodium appetite in mice

A main vector of the effects of stress is secretion of corticotrophin relea sing factor (CRF), adrenocorticotrophin (ACTH), and adrenal steroids. Syste mic administration of ACTH (2.8 mu g/day sc) for 7 days in BALB/c mice caus ed a very large increase of voluntary intake of 0.3 M NaC1 equivalent to tu rnover of total body sodium content each day. Intracerebroventricular infus ion of ACTH (20 ng/ day) had no effect. Intracerebroventricular infusion of ovine CRF (10 ng/h for 7 days) caused an increase of sodium intake. The la rge sodium appetite-stimulating effect of systemic ACTH was not influenced by concurrent systemic infusion of captopril (2 mg/day). Induction of stres s by immobilization of mice on a running wheel caused an increase in Na app etite associated with a 50% decrease of thymus weight, indicative of cortic osteroid effects. The present data suggest that stress and the hormone casc ade initiated by stress evoke a large sodium appetite in mice, which may be an important survival mechanism in environmental conditions causing stress .