Differences in locomotor activity before and during the access to food in a restricted feeding protocol between obese and lean female mice Neotomodon alstoni

Abstract

The anticipatory locomotor activity to a restricted food access is one of the main behavioral references in experimental protocols that allow us observing a circadian food entrainable oscillator (FEO) in rodents. The persistence of the anticipatory activity to food access has been subject of diverse studies in order to explore the mechanism that generates this particular circadian oscillator; however, few studies involving obese animals in the expression of the FEO have been nowadays performed. Most of the attention has been focused in the anticipatory locomotor activity but other activity components have received less attention. In the present study, we compare the locomotor activity profile between lean and obese mice Neotomodon alstoni, a species that in vivarium conditions differentially develop obesity when fed regular chow rodent food. Freely moving locomotor activity was monitored by means of infrared light beams. A protocol consisting of 5 h food access during the light phase was performed on lean and obese mice in light–dark conditions and also, a protocol of complete darkness and 2 days fasting was tested. Our results present differences in the amount of locomotor activity in each experimental condition, particularly, the anticipatory activity in obese is not as robust as in lean mice, but there is clearly an activity bout present during the food access in obese mice. Such component persists in fasting and constant darkness condition indicating that it may be part of the behavior expressed by the food entrained oscillator in obese mice.

Keywords:

• circadian
• food entrained oscillator
• obesity
• Neotomodon
• locomotor activity

Acknowledgements

We thank Teresa Bosques for English edition. This project was supported by PAPIIT-UNAM IN225311 with a fellowship to César Luna-Illades.