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To assess the effects of chronic methadone administration on locomotor, social, and eating behavior of drug-naive individuals under circumstances approximating those of methadone 'maintenance' clinics, we gave single, daily oral doses of methadone to 5 Macaca radiata monkeys living in a social group. We obtained motor activity counts automatically during 6 weeks of baseline, 10 weeks of drug administration, and 3 weeks of post-drug abstinence. Social behaviors of association, dominance, submission, and sexuality were counted 5 days per week, and animal weights, food eaten, and food-reinforced work were recorded. Plasma methadone levels were near those achieved in methadone clinics. Methadone produced mixed stimulation and sedation in the daytime, with stimulation predominating for 4 hrs following administration. At night the subjects moved less while taking the drug. Associative behaviors were reduced by methadone, but dominance, submission, and sexual behaviors were not altered. The monkeys ate less while taking the drug, losing weight and working less for food. In these primates methadone had significant stimulant properties, impaired important social behaviors, and reduced the potency of food as a reinforcer of work. The results are compared with methadone's effects upon humans. [ABSTRACT FROM AUTHOR]

To clarify the effects of different doses of methamphetamine HCl, Na phenobarbital, and imipramine HCl on aggressive behavior, the drugs were administered to pairs of rats trained to regularly fight on an electric shock grid. Fighting time and motor activity were measured during the shock sessions. Each drug was given to a different group of rats, in the following doses (mg/kg i.p.): methamphetamine HCl 0, 0.25, 0.50, 1, 2, and 4; Na phenobarbital 0, 5, 10, 20, 40, and 80; imipramine HCl 0, 2.5, 5, 10, and 20. At lower doses methamphetamine and phenobarbital both stimulated fighting behavior, and at higher doses both reduced it. Motor activity rose above control with lower doses of both of these drugs; it fell markedly with higher doses of phenobarbital, while remaining elevated at higher doses of methamphetamine. Imipramine reduced fighting time at higher doses. The results show that, depending upon the dose, the 'stimulant', methamphetamine, and the 'sedative', phenobarbital, can both increase or decrease aggressive behaviors. Together with previous animal studies, these findings fit with clinical observations that amphetamines and barbiturates can increase aggressive behavior, and suggest that dose may be important in that increase. [ABSTRACT FROM AUTHOR]