Experimental menopause in 3xTg-AD mice triggers metabolic and cognitive dysfunction aligned with Alzheimer's disease processes

There is a compelling link between menopause and Alzheimer's disease (AD), with few established molecular mechanisms. A lack of experimental models limits validation of causal drivers of these interactions. Here, we characterize the accelerated ovarian failure (OF) model of menopause in the triple-transgenic AD (3xTg-AD) mouse. Ovotoxin, 4-vinylcyclohexene diepoxide accelerated follicular loss, ablating circulating progesterone. OF resulted in decreased performance in the Y-maze, Novel Object Recognition, and Barnes Maze, consistent with accelerated AD. OF aggravated age-related impaired glucose tolerance and caused insulin resistance and these alterations correlated with the degree of cognitive impairment. Transcriptomic analyses of the mouse hippocampus identified 19 differentially regulated genes in OF mice, including some linked to AD, including C4b, Ifit3b, Cxcl13 and Gabrg2. We produced new transcriptomic profiles of dementia-free human entorhinal cortex (n=99) and remodeled entorhinal cortex profiles from patients (n=64; Braak scores 0-6). Analyses of our 19 OF genes, identified that C4B expression was upregulated with both age and Braak score, while several revealed novel co-expression relationships, including between Shootin (SHTN1) and GABA receptor subunit (GABRG2). In summary, accelerated ovarian failure presents key cognitive, metabolic and molecular changes associated with age-related decline in cognitive function, indicating that it can be useful for the identification of novel therapeutic targets Female triple-transgenic AD (3xTg-AD)(26) mice were purchased through The Jackson Laboratory and the NIH supported Mutant Mouse Resource and Research Center (MMRRC). Mice were housed four animals per cage in an AAALAC-accredited animal facility at the University of Miami Miller School of Medicine. Ovotoxin vinylcyclohexene dioxide (VCD; Sigma, cat. #94956) was diluted in sesame oil (Fisher Scientific, cat #18-606-186). Animals were administered 160 mg/kg VCD (n = 19) to induce OF or sesame oil vehicle (n = 20) at a final volume of 100µL intraperitoneal (i.p.) starting at 4 months of age. Mice were injected 5 days a week for 3 weeks, for a total of 15 days. Mice representing peri-OF (Ctrl n = 9; VCD n = 8) were euthanized 90-100 d.p.i., when mice were 30-32 weeks old. Mice representing post-OF (Ctrl n = 10; VCD n = 10) were euthanized 217-224 d.p.i., approximately 48 weeks old. 28 RNA samples were successfully processed to completed CEL files passing QC.