Inhibition of feeding by ACTH-(1-24): behavioral and pharmacological aspects.
The time course of the behavior of rats fasted for 24 h was analyzed with observation starting either 10 or 60 min after the i.c.v. administration of ACTH-(1-24) (4 micrograms/animal). The anorectic effect of this peptide was direct and specific because it could be dissociated in time from the grooming-inducing effect. The effect is a central one, not linked either to an interaction with the peripheral feeding-regulatory system, or to the release of adrenal steroids. ACTH-(1-24), like corticotropin-releasing factor (CRF), is capable of antagonizing the stimulation of feeding seen during starvation, insulin (10 IU/kg s.c.)-induced hypoglycemia, stimulation of GABAergic (muscimol, 250 ng/rat i.c.v.), noradrenergic (norepinephrine, 20 micrograms/rat i.c.v.) or opioidergic systems. The data suggest that both CRF and ACTH may be considered as putative mediators in the production of stress-induced anorexia.