Figure 1.

Schematic of the study procedure (A) and timeline of experimental design (B). Firstly, the voles were cohoused for 4 days to allow for the formation of a pair bond (phase 1). Then the subjects were randomly assigned to 1 of 3 groups: control (CTR), emotional stress (ES), and physical stress (PS) (phase 2). In the CTR group, the subjects were put in the residents’ cage where they were separated from each other by clear perforated acrylic glass. In the ES group, the subjects were put in cages where they would witness the social defeat bouts of their partners by an aggressive resident. In the PS group, the subjects were directly put in the residents’ cage without separators where they were defeated by the resident. Following each session (10 min/d), the subjects were returned to their original home-cages and cohoused with their partners. This procedure lasted for 14 consecutive days and then the subject voles were tested on the consolation test (phase 3), where their partners were defeated and the consolation behaviors of the subjects were recorded. For detailed procedures, please refer to the text. OFT, open-field test; P, partners; R, residents; S, subjects; SI, social interaction test; TST, tail suspension test; WB, western blot.