Effects of methaqualone on social-sexual behavior in monkeys (M. mulatta) II. Simultaneously dosed subjects

In a previous publication, we reported on the effects of 10 mg/kg i.m. injections of methaqualone on behavioral changes in treated animals and untreated members of a well-established colony of 10 rhesus monkeys (Macaca mulatta). The drug showed a biphasic effect, causing more passive behaviors in the first 80-100 min postinjection, followed by either aggression or increased sexual activity. After approximately 2 h, the social status and behavior of all animals returned to predrug levels. In general, affiliative activities increased under the influence of the drug, phenomena somewhat parallel tho those described among humans taking methaqualone in group settings. We also speculated that the drug may have an aphrodisiac potency. In the present experiments, 3 animals were caged together and injected simultaneously with the dose used earlier: an adult but naive male, who had been caged alone for infancy; an adult and subadult female, the 2 latter having had extensive social experience. After establishing baseline behaviors, five experiments with methaqualone were conducted, each lasting 2 h; and after the 2nd and 4th experiments, saline controls were carried out. There was a continuous increase from experiment to experiment in the affiliative behaviors of the animals; but during the saline trials, their behaviors returned nearly to those exhibited during baseline studies. Under the influence of methaqualone, the naive male attempted to copulate, which he achieved by the 4th drug trial; and at the same time he established his dominance. The conclusion was reached that methaqualone, indeed, has aphrodisiac potency, best measured by the time the male spent with erection under the influence of the drug, as compared with no erection during the baseline studies or the saline trials. The biphasic effect of methaqualone on behavior reported in the previous review [1] was also observed during the present experiments.