Deletion of UCP1 in Tg2576 Mice Increases Body Temperature and Exacerbates Alzheimer's Disease-Related Pathologies

We previously demonstrated that the Alzheimer's disease (AD)-like model mice, Tg2576, housed at a high ambient temperature of 30 °C for 13 months, exhibited increased body temperature, which increased amyloid-β (Aβ) levels and tau stability, leading to tau phosphorylation and ultimately inducing memory impairment. Here, we aimed to exclude the possible effect of environmental factors associated with the difference in ambient temperature (23 °C vs. 30 °C) and to further clarify the effects of elevated body temperature on AD-like pathologies. We generated uncoupling protein 1 (UCP1) deletion in Tg2576 mice, Tg2576/UCP1^-/-, because UCP1 deletion mice show a sustained rise in body temperature at normal room temperature. As expected, the body temperature in Tg2576/UCP1^-/- mice was higher than that in Tg2576/ UCP1^+/+ mice at 23 °C, which was accompanied by upregulated Aβ levels due to increased β-secretase (BACE1) and decreased neprilysin (NEP) protein levels in the brains of Tg2576/UCP1^-/- mice compared with those in the Tg2576/ UCP1^+/+ mice. Elevated body temperature also increased total tau levels, leading to enhanced phosphorylation, heat shock protein induction, and activated tau kinases. Furthermore, elevated body temperature enhanced glial activation and decreased synaptic protein levels in the brain. Taken together, these findings demonstrate that elevated body temperatures exacerbate AD-like pathologies.