Overview of investigated mouse models and tissues for DOR expression analysis. For the diet model, NMRI mice were fed diets with different fat content. In the genetic model, 45 days old male mice from inbred lines DU6i and DUKsi were used (dashed box). All female animals and 100 days old male mice were DU6 and DUKs animals. The maximum number of animals from which tissues were processed is added. Exact counts of animals for each processed tissue are listed in Additional files 3 and 5.