Altered ambient temperature and ethanol-induced conditioned place preference in mice

Previous studies with rats exposed to altered ambient temperature T(a) or with mice selectively bred for their thermal response to ethanol have shown that a reduced hypothermic response is correlated with decreased place aversion and greater place preference, respectively. The present experiment was designed to test whether alterations in T(a) would alter ethanol's ability to produce conditioned place preference in genetically heterogeneous mice. Three groups of mice underwent a differential conditioning procedure that paired one distinctive floor texture with ethanol (2.25 g/kg, IP) and a different floor texture with saline. During conditioning, each group was exposed to a different T(a): cold (10°C), normal (21°C), or warm (34°C). Each group was further divided and subgroups were tested for preference at either the conditioning temperature or a different temperature. Consistent with previous findings, mice conditioned and tested at normal T, developed a conditioned preference for the ethanol-paired floor. In contrast, mice exposed to a warm or cold T(a) during conditioning or testing failed to show place conditioning. Although exposure to either warm or cold T, interfered with place conditioning, only the warm T(a) had an effect on hypothermia. These findings suggest that altered T(a) produced stimuli that may have interfered with the association between floor cues and ethanol during conditioning or interfered with expression of this association during testing.