Ameliorative effects of brief daily periods of social interaction on isolation-induced behavioral and hormonal alterations

• Social isolation in adulthood exerts major effects on rats' physiology and behavior.
• Brief daily periods of social interaction abolish or ameliorate isolation-induced behavioral alterations.
• Brief daily periods of social interaction ameliorate isolation-induced alterations in corticosterone levels.
• Partial isolation may be used as preventive treatment protecting rats from the deleterious effects of isolation.

The present study investigated the effects of brief daily periods of social interaction on social-isolation-induced behavioral and hormonal alterations and deficits. Adult male Wistar rats were allocated to one of three housing conditions: 1) social housing (two per cage); 2) social isolation (one per cage); or partial social isolation (one per cage with access to another male rat for 60 min/day). After 14 days in these different housing conditions, the animals were subjected to various behavioral tests, including sucrose preference test, acoustic startle response, two-way active shuttle avoidance, pre-pulse inhibition, open field, cooperation learning task, and levels of corticosterone. Results revealed that social isolation had a substantial impact on rats' performance on most behavioral tests as well as on their corticosterone levels. Importantly, however, the results clearly demonstrate that allowing otherwise isolated animals to have a brief (60 min) daily social contact with another rat to a great extent abolishes or ameliorates most of the isolation-induced behavioral and hormonal alterations. Hence, providing isolated animals with brief daily periods of social contact may be used as a “preventive treatment” in order to protect them from the deleterious effects of isolation.