Differential sexual activity of isolated and group-housed male mice: Influence of acute d-Amphetamine sulfate administration

It is established that group housing can impair sexual activity of male mice, and that central catecholamines are involved in male sexual response, but it is not known whether catecholamine mechanisms are involved in sexual impairment in grouped males. Injections of 0, 0.22, 0.67, 2.0, or 6.0 mg/kg of d-amphetamine sulfate were administered 1 h before testing to individually and group-housed male C57BL/6J mice. Isolated mice showed more mounts, intromissions, and ejaculations and shorter response latencies than did group-housed mice. The latencies to first mount, intromission, and ejaculation were nonmonotonically related to dosage, being shortest at the lowest dosage in isolated mice, but significantly elevated by the higher dosages in both isolated and grouped males. The number of ejaculations was significantly elevated by moderate dosages in both isolated and grouped mice, peaking at the 2.0 mg/kg dosage in isolated mice and at 0.67 mg/kg in grouped mice. Nevertheless, amphetamine treatment generally failed to eliminate differences between males from isolated and grouped backgrounds.