Low-Dose Lithium Rebuilds Muscle, Bone, and Metabolism After Estrogen Loss

Menopause-associated estrogen loss triggers a cascade of adverse changes—muscle weakness, bone loss, weight gain, and insulin resistance—that significantly elevate risk for sarcopenia, osteoporosis, and type 2 diabetes. While hormone replacement therapy can address some of these effects, it is contraindicated for many women. This study explored low-dose lithium (Li) supplementation as an alternative intervention, leveraging its well-characterized role as a glycogen synthase kinase 3 (GSK3) inhibitor.

Researchers used 28-week-old female C57BL/6J mice divided into three groups: surgical sham controls, ovariectomized (OVX) mice, and OVX mice receiving 50 mg/kg/day lithium chloride in drinking water (OVX-Li) for 8 weeks. This dose is well below the clinical bipolar therapeutic range and has been previously validated as safe and effective in male mdx mice. Outcome measures included skeletal muscle contractility (in vitro force-frequency and fatigue protocols for soleus and EDL), dual-energy X-ray absorptiometry (DXA) for body composition and bone mineral density, metabolic cage assessments, glucose and insulin tolerance tests, SERCA functional assays, oxidative stress markers, mitochondrial protein expression, and RNA sequencing of muscle tissue.

Lithium supplementation significantly enhanced isometric specific force production and fatigue resistance in both the slow-twitch soleus and fast-twitch EDL muscles of OVX mice. At the cellular level, SERCA-mediated calcium uptake was improved, oxidative stress was reduced, and key mitochondrial markers were upregulated in OVX-Li animals. RNA-seq analysis revealed that lithium broadly blunted the transcriptomic reprogramming induced by OVX surgery, effectively normalizing many gene expression changes toward sham levels. Bone mineral density, which was significantly reduced in OVX mice compared to shams, was restored to sham-comparable levels with lithium treatment. Insulin tolerance also showed modest but meaningful improvement in OVX-Li animals, though glucose tolerance results were less definitive.

The mechanistic picture that emerges points to GSK3 inhibition as a unifying pathway: GSK3 suppression promotes Wnt/β-catenin signaling (supporting osteogenesis), reduces protein degradation pathways in muscle, enhances mitochondrial biogenesis, and improves glycogen metabolism and insulin signaling. The RNA-seq findings are particularly compelling, suggesting lithium does not merely treat individual symptoms of estrogen deficiency but may reprogram broader pathological gene expression patterns.

Importantly, the dose used (50 mg/kg/day, yielding serum Li ~0.15 mM) remained well below nephrotoxic thresholds documented in mice and far below clinical bipolar dosing. However, the study is preclinical only, conducted exclusively in mice, and lacks direct human translational validation. The absence of a sham-Li group also limits conclusions about whether lithium's benefits are specific to the OVX context or apply more broadly.