sulted in a moderate number of attack bites (30); this resulted in the mice consuming large amounts (15–30 g/kg/day) of the alcohol solution. Earlier sensitization to cocaine or amphetamine did not predict later alcohol or cocaine self-administration.
When the researchers injected the rodents with antagonists of the receptors for corticotropin-releasing factor, a hormone and neurotransmitter important in stress response, prior to each episode of social defeat, the rodents did not escalate their cocaine or alcohol self-administration, indicating that CRF plays an essential role in the process by which stress makes animals prone to using substances.
In related research by Camilla Karlsson and colleagues, IL-1R1 and TNF-1R, the receptors for two inflammatory cytokines, mediated the effects of social stress on escalated alcohol use in mice.