AMPK-mediated autophagy induction by bisdemethoxycurcumin attenuates senescence and amyloid pathology in 3xTg-AD mice

Alzheimer disease (AD) pathology is accompanied by increased senescence and reduced levels of autophagy in the brain. We investigated whether pharmacologically inducing autophagy could alter the senescent phenotype and ameliorate AD pathology. We discovered that Bisdemethoxycurcumin (BDMC), a natural compound found in Curcuma longa, stimulates autophagy in primary astrocytes. We found that autophagy and senescence exhibit an inverse relationship in aging astrocytes, with increased expression of senescent proteins and downregulation of autophagic proteins. However, treatment of aged astrocytes with BDMC reversed the senescent phenotype by ameliorating the impaired autophagy. Interestingly, the senescent phenotype persisted when autophagy was downregulated by knockdown of AMPK. Additionally, BDMC-induced autophagy aided in the removal of amyloid beta (Aβ) that was administered externally to the astrocytes. Further, to validate these results in a mouse model of AD, we confirmed that BDMC significantly penetrates the blood-brain barrier (BBB) in mice. Therefore, we administered 50 and 100 mg/kg b.w. of BDMC to transgenic 3xTg-AD mice for two months. In their hippocampus, the Control 3xTg-AD animals showed more senescent cells and lower autophagy levels. In contrast, autophagic proteins were significantly upregulated while senescence indicators, such as senescence-associated secretory phenotype (SASP) proteins, were sharply downregulated in the brain of treated animals. We discovered that the hippocampus of treated mice had a significantly lower Aβ load. These molecular changes in the brain were ultimately reflected in the improved working memory and neuromuscular coordination behavior of mice treated with BDMC. This study warrants further evaluation of BDMC for the management of AD.