Sensitivity and tolerance to ethanol-induced incoordination and hypothermia in HAFT and LAFT mice.

Acute functional tolerance (AFT) manifests as rapid adaptation during a single ethanol exposure, leading to a decrease in the behavioral response to ethanol. In order to investigate the genetic and environmental components of the development of AFT, mice were selectively bred in replicate from HS/Ibg mice. High (HAFT) and low (LAFT) acute functional tolerance selected lines were bred to differ in the rate of development and magnitude of AFT to ethanol's intoxicating effects using a static dowel-balancing task. In the present set of experiments, HAFT and LAFT mice were tested for development of AFT on a fixed-speed rotarod using a protocol similar to that for which they were selected. HAFT mice developed greater AFT to ethanol than did LAFT mice. In a separate experiment, other mice from these lines were tested for initial sensitivity and the development of chronic tolerance to ethanol-induced hypothermia, and ethanol-induced incoordination in the grid test. Previous research has detected possible common genetic control of these phenotypes. No differences between lines were found in initial sensitivity to ethanol or in the development or magnitude of chronic tolerance in either test. These experiments show that genetic factors influencing the development of acute tolerance to ethanol-induced intoxication are at least partially distinct from those influencing initial sensitivity and the development of chronic tolerance to ethanol-induced hypothermia and incoordination. Furthermore, these experiments show that AFT measured by the stationary dowel generalizes to AFT measured by the fixed-speed rotarod.