Comparison of C57BL/6 and DBA/2 mice in food motivation and satiety.

Demand functions describe the relationship between the consumption of a commodity and its mean or unit price. In the first experiment, we analyzed food demand in two strains of mice (C57BL/6 and DBA/2) that differ on several behavioral dimensions, but have not been examined extensively for differences in feeding and meal patterns. Mice worked for food pellets in a continuous access closed economy in which total intake and meal patterns could be measured. A series of fixed (FUP), variable (VUP), and progressive (PUP) unit price schedules were imposed. Under all schedules, DBA/2 mice consumed significantly more food than C57BL/6, a difference that was not attributable to disparity in body weight or weight gain. The higher intake of DBA/2 mice was due predominantly to larger meal size compared with C57BL/6, with no strain difference in meal frequency. In a second experiment, strain differences in meal size were not found to correlate with anorectic sensitivity to cholecystokinin (CCK) administration, or with c-Fos expression induced by CCK in PVN, AP and NTS. Thus, DBA/2 mice were motivated to sustain a higher daily food intake and meal size than C57BL/6 under the range of demand costs employed in the present work, but this strain difference is unlikely to be due to CCK action or responsiveness. (c) 2010 Elsevier Inc. All rights reserved.