Effects of chronic treatment with ipsapirone and buspirone on the C57BL/6J strain mice under social stress.

We experimented on inbred C57BL/6J strain mice who experienced social stress caused by defeat in inter-male confrontations for 20 days. From the fifth fight on, some mice were injected with ipsapirone (3 mg/kg), and some with buspirone (1 mg/kg) on a daily basis, for 14 days. Post-treatment behavior was examined in the plus-maze, partition, and Porsolt forced swim test (Porsolt's test). Each of these drugs had anxiolytic effects in the plus-maze, suggesting that they reduce state anxiety. Neither had any effect in the partition test, which provides further support to the hypothesis that normally the C57BL/6J strain mice have a high level of trait anxiety and for that reason they did not respond to the drugs. Chronic treatment with neither drug had any effect in the Porsolt's test. It is proposed that ipsapirone and buspirone fail to alleviate the depressive-like behaviors in the C57BL/6J mice because of a high level of trait anxiety, which might be inherent to this mouse strain.