Food deprivation reduces microglia in the rat brain in association with reduced body temperature

The involvement of microglia (MG) in neuroinflammatory responses has been demonstrated extensively. Recent studies have suggested that dietary restriction suppresses microglial activity; however, the relationship between food deprivation (FD)-induced hypothermia and microglial alterations remains unclear. In the present study, we examined the effects of FD on body temperature (Tb) and Iba1-immunoreactive (Iba1-ir) microglial cells in the hippocampus, thalamus, hypothalamus, and cerebral cortex of rats. Tb was monitored throughout the experimental period, and microglial morphology, cell number, and their correlation with Tb were evaluated following up to 3 days of FD. The results demonstrated that (1) FD significantly reduced Tb during the dark phase, but not during the light phase; (2) FD also decreased microglial density and induced morphological changes consistent with reduced microglial activation in all brain regions examined; (3) there was a positive correlation between Tb and microglial densities in brain regions, except for the cerebral cortex, which showed no significant correlation. These findings demonstrate that FD suppresses microglial activation in multiple brain regions in association with reduced Tb, suggesting that metabolic adaptation to FD modulates neuroimmune homeostasis and may contribute to mechanisms that attenuate neuroinflammation.