IKKβ signaling mediates metabolic changes in the hypothalamus of a Huntington’s disease mouse model

Abstract

Background: Huntington's disease (HD) is a neurodegenerative disorder caused by a CAG repeat expansion in the huntingtin (HTT) gene. Metabolic changes are associated with HD progression, and underlying mechanisms are not fully known. As the IKKβ/NF-kB pathway is an essential regulator of metabolism, we investigated the involvement of IKKβ, the upstream activator of NF-kB in hypothalamus-specific HD metabolic changes. Methods: Using viral vectors, we expressed amyloidogenic N-terminal fragments of mutant HTT (mHTT) fragments in the hypothalamus of mice without IKKβ in the CNS (IKKβ-/-) and control mice (IKKβ+/+). We assessed effects on body weight, metabolic hormones, and hypothalamic neuropathology. Results: Hypothalamic expression of mHTT led to an obese phenotype only in female mice. CNS-specific inactivation of IKKβ prohibited weight gain in females, which was independent of neuroprotection and microglial activation. Conclusions: The expression of mHTT in the hypothalamus causes metabolic imbalance in a sex-specific fashion, and central inhibition of the IKKβ pathway attenuates the obese phenotype.