Thread by @nick_krontiris

The findings of this study in a rodent model that permits some separation of the effects of a Western, obesogenic-type diet and obesity on glucose homeostasis, suggests that impairments in glucose homeostasis are largely driven by ectopic fat storage.

- Voles are small, non-hibernating rodents that have an annual cycle of body weight change that reflects large changes in their levels of adiposity.

Interestingly, this state can be induced by manipulations of photoperiod, independent of the diet.

This means that simply by switching the light regime in the room where the animals are housed, a lean vole can be turned into a vole with obesity within the space of about 5 weeks without any change in the diet.

- In this study, Brandt’s voles were exposed to either long or short photoperiods, and under each photoperiod treatment, they were also exposed to either a higher-fat or a lower-fat diet.

For the higher-fat diet, a diet with 26% calories from fat was used.

"This is because voles refused to eat diets with very high fat contents (>40%), and 26% is more in line with recommendations to match human obesogenic diets.

- Exposing voles to photoperiod and an obesogenic, higher-fat diet allowed the group to separate the impacts of diet and adiposity on glucose homeostasis:

- There was a large effect of the higher-fat feeding diet on glucose intolerance, but no effect of adiposity that stemmed from the photoperiod change.

- This impairment of glucose homeostasis under the higher-fat feeding was accompanied with changed ectopic fat deposition, particularly in skeletal muscle.

- The same impacts on both glucose homeostasis and ectopic fat deposition were not associated with expanding adiposity driven by photoperiod change.

- These findings suggest that impairment of glucose homeostasis is largely driven by the level of any particular manipulation on ectopic fat storage.

Disentangling the effects of obesity and high-fat diet on glucose homeostasis using a photoperiod induced obesity model implicates ectopic fat deposition as a key factor (open access)

doi.org/10.1016/j.molm…

#MetabolicSyndrome #InsulinResistance #Obesity