Effects of binge-like ethanol drinking on nest building behavior in mice.

Nest building is a natural behavior that can readily be analyzed in mice in the home cage environment. Nest building is involved in thermoregulation, positive motivational states, and motor function, and alterations in this behavior have been proposed as an index for ethanol withdrawal severity in mice. However, nest building outcomes after voluntary ethanol consumption have not been examined. Here, we tested male and female C57BL/6J mice on a 4-day drinking in the dark (DID) paradigm of binge-like drinking with either ethanol or a water control and analyzed nest scores at two timepoints (48 h and 7 days) after the last DID session. At 48 h after the last DID session, there were no differences between the two groups in nest quality. At 7 days after DID, ethanol-drinking animals showed significantly lower nest scores than the water group (z = -2.369, p = 0.030). No differences were found between the ethanol- and water-drinking groups in locomotor activity or anxiety-like behavior at this timepoint in an open field test, indicating that nest building deficits in the ethanol group were likely not due to underlying differences in these behaviors. Together, these results validate the use of nest building as a naturalistic assessment of post-ethanol behavioral changes following voluntary binge-like drinking.