Resident–intruder test

The resident–intruder test was used to measure aggressive behavior. SI mice were housed singly for 2 weeks, and intruder mice were housed at a density of 3–4 mice per cage before the test. The behavior of each resident mouse was scored blindly for total attack count, attack duration, and attack latency. An attack was defined as a single bite or a flurry of rapid bites initiated by the resident. The bedding in the cages housing the resident mice was not renewed for 3 days before the test.