The effect of social factors on the anxiolytic efficacy of buspirone in male rats, male mice, and men.

Earlier findings suggest that housing conditions in laboratory animals and life events in humans influence the efficacy of anxiolytic drugs. Here we report on the impact of social isolation on buspirone efficacy in male mice and rats as assessed by the elevated plus-maze. In addition, the impact of social support on buspirone efficacy was assessed in male patients. When administered 30 min before testing and irrespective of housing conditions, buspirone significantly suppressed locomotor activity both in mice (6 mg/kg) and rats (10 mg/kg) and, as such, other behavioral changes observed at this time point must be seen as behaviorally nonselective. However, these locomotor disruptive effects of buspirone were not evident in either species at longer injection-test intervals (2 and 4 h). When given 2 h prior to testing, a low (3 mg/kg) but not high (10 mg/kg) dose of buspirone increased the frequency of open arm exploration in rats (but not mice) irrespective of housing conditions. At the longest injection-test interval used (4 h), buspirone increased the duration of open arm exploration in individually housed, but not group-housed, rats. Similar, though somewhat less robust, effects were observed in male mice at this time. In a double-blind placebo-controlled study with male patients, chronic buspirone treatment (3 x 10 mg daily for 6 weeks) produced a highly significant reduction in scores on the Hamilton Rating Scale for Anxiety (HAM-A). Multiple regression analysis of social support received by patients indicated that the support of nonrelatives (but not of family or other relatives) was a strong positive predictor of buspirone efficacy. Taken together, our data support the hypothesis that social conditions affect the anxiolytic efficacy of buspirone. Results are discussed in relation to differences in the social organization of the three species investigated.