Effects of naloxone on the behaviors evoked by amphetamine and apomorphine in adult cats

Abstract

1. 1. This work was undertaken in order to study whether the opioid system is involved in the modulation of the behaviors induced by two agonists of the dopaminergic system, amphetamine and apomorphine in adult cats. 2. 2. Naloxone, an antagonist of the mu, delta and kappa opioid receptors was administered to twelve female mongrel cats; 0.5, 1.0 and 2.0 mg/kg s.c. were injected in order to analyse its own effect of naloxone. This drug produced NREMs behavior and accordingly the cat showed an overall decrease of its activities. 3. 3. Amphetamine (2.5 mg/kg s.c.) and apomorphine (2.0 nog/kg s.c.) were injected before and after naloxone administration (2.0 mg/kg s.c.), in separate sessions. 4. 4. The behaviors recorded were compared. Some of the behaviors showed modifications both with amphetamine (inappetence was increased and locomotion decreased) and apomorphine (indifference and inappetence increased; locomotion and olfaction decreased). 5. 5. These changes were considered as conseque