Mice bearing Acads mutation display altered postingestive but not 5-s orosensory response to dietary fat

1 Obesity Division and 2 Department of Biostatistics, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, Louisiana 70808 Submitted 25 August 2003 ; accepted in final form 28 October 2003 A previous survey of mouse inbred strains revealed a wide range in self-selected fat intake, from 26 to 83% of energy. The BALB/cByJ strain selected a lower percentage of fat intake (36%) than all other strains tested except for the CAST/Ei. BALB/cByJ mice are deficient in the short-chain acyl-CoA dehydrogenase (SCAD) enzyme due to a spontaneous mutation in Acads . We hypothesized that this deficiency would alter fat appetite and used three behavioral test paradigms to compare the response of BALB/cByKz. Acads -/- and BALB/cByKz. Acads +/+ mice to fat stimuli. First, during 10-day exposure to a macronutrient self-selection diet, Acads -/- mice consumed proportionately less fat and more carbohydrate than Acads +/+ mice, yet total energy intake was similar between strains. Next, in 48-h two-bottle preference tests, Acads +/+ mice displayed a preference for 50% corn oil, but Acads -/- mice did not. Finally, in brief-access taste tests employing successive 5-s presentations of corn oil in an ascending concentration series ending with 50%, there were no effects of strain on total licks, indicating that Acads does not alter acute orosensory response to this fat stimulus. With 15-s presentations, however, the Acads +/+ mice licked more of the 50% oil than Acads -/-, suggesting orosensory effects related to the increased exposure time. In contrast to corn oil, there were no strain differences in licking response to sucrose solution in either the two-bottle or brief-access taste tests. The observation that SCAD-deficient mice display altered postingestive responses to dietary fat provides further evidence for the metabolic control of feeding. taste; ingestive behavior; licking frequency; diet selection Address for reprint requests and other correspondence: B. K. (Smith) Richards, Pennington Biomedical Research Center, 6400 Perkins Rd., Baton Rouge, LA 70808-4124 (E-mail: richarbk{at}pbrc.edu ).