Dba 2j males

C57BL/6J females were bred with DBA/2J males (The Jackson Laboratory, Bar Harbor, ME) and were fed control diet (Test Diet, Richmond, IN #5755; 18.5% protein, 12% fat, 69.5% carbohydrate) throughout pregnancy and lactation. Offspring were weaned at 3wks of age and a third of the animals were placed on high fat diet (Test Diet, #58G9; 18% protein, 60% fat, and 20.5% carbohydrate). Another third of the animals were placed on high fat diet at 6wks of age. The final third were kept on standard chow. Animals remained on the high fat diet for 12 weeks. In an additional cohort of animals, after 12 weeks ad lib access to the high fat diet, the diet was returned to control chow for 4 weeks. Separate cohorts of animals were used for the behavioral studies and the molecular studies, and animals were group housed (5 mice/cage), except where noted for behavioral experiments. Body weights were recorded weekly, and both male (n=5–10/experiment) and female (n=5–10/experiment) mice were used for the behavioral experiments. Given that binge behavior was only observed in females, experiments to measure dopamine and dopamine-related gene expression changes were conducted in female mice. The Institutional Animal Care and Use Committee (IACUC) of the University of Pennsylvania approved all procedures.

B6D2F1 hybrids were generated through in house breeding of C57BL/6J females and DBA/2J males (Jackson Laboratories, Bar Harbor ME). Animals were fed an ad-lib diet (Teklad LM-485, Madison WI) and maintained on a 12 hr light – dark cycle in standard microisolator cages. Lights were on from 07.00 till 19.00 h, then switched to a reverse light-dark cycle for behavioral experiments (see details below). Upon weaning at PN21 animals were grouped housed 3–4 mice per cage. All animals were cared for according to the guidelines of the University of Cincinnati Institutional Animal Care and Use Committee.