Effects of intraperitoneal injections of saline on the alcohol and sucrose consumption of C57/BL10 mice

Rationale: To determine the effects of multiple saline injections on alcohol drinking by male and female C57/BL10 mice with low preference for alcohol. Objective: An investigation of the effects of multiple saline injections on alcohol consumption, with a comparison of corresponding effects on sucrose consumption. Methods: The effects of a range of injection schedules on preference for 8% alcohol, or 1% sucrose, compared with tap water, were measured in two-bottle choice tests. Results: The multiple saline injection schedule significantly increased the alcohol preference, even when no alcohol was available during the injection period. The actual administration of fluid was not necessary for the increase in alcohol preference, since sham injections without fluid administration also increased alcohol preference. A single injection of saline did not alter the alcohol preference 3 weeks later. Daily saline injections for 3 weeks did not alter the consumption of the dilute sucrose solution. In the population of mice used, the preference for sucrose over water was found to follow a biphasic distribution, similar to that reported earlier in these mice for alcohol preference, but there was no correlation between alcohol preference and sucrose preference. Conclusions: The results suggest that lasting changes in the areas of the brain that specifically control alcohol intake are produced by repetition of a routine laboratory procedure.