Tolerance develops to the behavioural effects of ACTH-(1-24) during continuous i.c.v. infusion in rats, and is associated with increased hypothalamic levels of beta-endorphin.
In rats, the continuous infusion of ACTH-(1-24) into a brain lateral ventricle (0.5 micrograms/h in the volume of 1.11 microliters, for 7 days) caused a significant inhibition of the subsequent behavioural response to the acute intracerebroventricular injection of the same peptide. Tolerance developed to all the most typical signs of the ACTH-induced behavioural syndrome (grooming, stretching, yawning, penile erection, inhibition of food intake), and was associated with a significant increase in the hypothalamic levels of beta-endorphin immunoreactivity.
Vergoni
A V
AV
Department of Pharmacology, University of Modena, Italy.
Poggioli
R
R
Facchinetti
F
F
Bazzani
C
C
Marrama
D
D
Bertolini
A
A
D000324:Adrenocorticotropic Hormone / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects; D004326:Drinking; D004361:Drug Tolerance; D004435:Eating; D007031:Hypothalamus / Q000378:metabolism*; D007263:Infusions, Parenteral; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D001615:beta-Endorphin / Q000378:metabolism*
D001615:beta-Endorphin; D000324:Adrenocorticotropic Hormone