Effect of apomorphine on rat motor activity induced by fencamfamine and other indirect psychostimulant drugs

• Published in: Brazilian journal of medical and biological research Vol. 28; no. 9; pp. 995 - 998
• Main Authors: Aizenstein, M L, da-Silva-Planeta, C, DeLucia, R, da-Silva, C S
• Format: Journal Article
• Language: English
• Published: Brazil 01.09.1995
• Subjects: Amphetamine - pharmacology; Analysis of Variance; Animals; Apomorphine - pharmacology; Behavior, Animal - drug effects; Central Nervous System Stimulants - pharmacology; Cocaine - pharmacology; Dopamine Agents - pharmacology; Dopamine Agonists - pharmacology; Dopamine Uptake Inhibitors - pharmacology; Male; Motor Activity - drug effects; Norbornanes - pharmacology; Rats; Rats, Wistar
• ISSN: 0100-879X

We evaluated the effects of low doses of apomorphine on the stimulant behavioral effects induced by amphetamine (2.5 mg/kg), fencamfamine (6.0 mg/kg) and cocaine (15.0 mg/kg). Rats received 0.02 mg/kg of apomorphine (sc) and 30 min later were injected with one of the stimulants. Motor activity including locomotion, rearing and sniffing was quantified in the animals home cages for 60 min at 15-min intervals. All stimulant drugs induced hyperactivity. When apomorphine was administered before cocaine, but not when administered before fencamfamine or amphetamine, distinctive changes occurred. The behavioral pattern resulting from high stimulation was replaced by that related to low stimulation, suggesting that apomorphine induces a transfer in the predominant behavior in cocaine-, and partially in fencamfamine-, but not in amphetamine-treated animals, by decreasing the intensity of the stereotyped effect. While no changes occurred when apomorphine was administered before amphetamine, the fencamfamine group showed intermediate alterations (nonsignificant changes in sniffing but a significant increase in rearing behavior). These results are discussed in terms of the different mechanisms of presynaptic action of the drugs studied.