(Image: Leonid Zingman, University of Iowa)

An injection and a dash of exercise could be the secret to keeping trim. These rainbow mice, imaged in infrared to reveal how much energy they are burning while on a treadmill, are revealing how a shot can boost a muscle’s ability to burn calories.

Red body parts show where lots of energy is being used. The mouse on the right has a red patch on its left hind leg, which corresponds to the spot where it received an injection of a substance developed by Denice Hodgson-Zingman from the University of Iowa and colleagues.

The substance is a type of morpholino, a compound that can be designed to target specific genes, in this case to alter proteins responsible for storing energy. The disruption causes muscles to burn more energy even during mild exercise, such as a gentle trot on a treadmill.


In contrast, the untreated mouse on the left, which is doing the same amount of exercise, is using less energy in the same spot, as illustrated by the colder green colour.

The researchers hope the injection will help people who want to burn more calories do so through routine everyday activities, eliminating the need for intense exercise.

Journal reference: Molecular Therapy, DOI: 10.1038/mt.2015.21