Acute heat stress induces jumping escape behavior in mice.

A new heat escape behavior was revealed in mice (ddY mice) under acute heat stress conditions. Mice in a fully covered cage were exposed to 24, 34, 37 and 38.5 degrees C for 60 min. Rectal temperature increased in conditions above 34 degrees C. Furthermore, serum osmolality and body weight loss also increased in conditions above 37 degrees C. At above 37 degrees C, a large number of mice attempted to escape from the partially covered cage, and so exhibited jumping behavior during a period of 60 min. However, mice exposed to 24 and 34 degrees C did not exhibit such behavior. These results indicated that acute heat stress above 37 degrees C induced evaporative water loss and jumping escape behavior in mice.