Induction of Repeated Social Defeat Stress in Rats.

Repeated social defeat stress (RSDS) is a model of chronic stress in rodents. There are several variants of social defeat procedures that exert robust effects in mice, but few published detailed protocols to produce a robust stress and altered immunological profile in rats. In this article, we describe the protocol for the induction of RSDS in adult male Sprague-Dawley rats. Using a resident-intruder paradigm, a physical component of stress is induced by direct attack from the resident aggressive retired breeder Long-Evans rats on the intruder experimental rats. A subsequent threat component is induced by the presence of the aggressor in the vicinity of the intruder, but with physical separation between them. The RSDS induced by this protocol produces robust immunological and behavioral changes in the experimental rats, as evidenced by development of anxiety-like behaviors in open field, social interaction, and elevated plus maze tests, as well as by changes in immune parameters (Munshi et al., 2020). This approach has been used as an ethologically relevant model of stressors that are potent enough to impact neural circuits that are similar to the neural circuits impacted in patients with depression and anxiety.