Estrogen deprivation induces hepatic inflammation, Indoleamine-2,3-dioxygenase 1, tryptophan catabolism, and plasma cholesterol.
Level 5 - mechanism / opinion, no new human data
Animal model study without human clinical data
PubMed 42031929 · doi:10.1038/s41598-026-48938-w
What was done
Ovariectomized (OVX) Long-Evans rats were used as a model of estrogen deprivation to investigate hepatic inflammation, tryptophan catabolism, and cholesterol homeostasis. The study compared intact female rats, untreated OVX rats, and OVX rats receiving estradiol (E2) replacement. Measured outcomes included body weight, lipid profiles (LDL, total cholesterol, HDL), hepatic expression of inflammatory cytokines (TNFα, IL6) and enzymes/transporters (IDO1, TDO2, SR-BI), plasma markers (kynurenine, nitric oxide, lactate), and targeted LC-MS metabolomics.
What was found
OVX rats gained more weight and exhibited increased LDL and total cholesterol and decreased HDL compared to intact controls, changes that were reversed by E2. Hepatic expression of TNFα, IL6, IDO1, and TDO2 increased, whereas SR-BI expression decreased; E2 reversed these shifts. Plasma kynurenine, nitric oxide, and lactate rose after ovariectomy and were normalized by E2. Metabolomics showed increased tryptophan-to-kynurenine flux, elevated lactate, accumulation of citrate/isocitrate/aconitate, and a decreased α-ketoglutarate/aconitate ratio (~0.6 in OVX vs ~3.6 with E2). Exact animal numbers, baseline values, and statistical intervals were not reported in the abstract.
Why it matters
This work identifies a mechanistic link between estrogen deficiency, hepatic inflammation, and tryptophan-kynurenine pathway activation, suggesting potential metabolic targets for postmenopausal cardiometabolic risk.
Limits
The study is limited to a rodent ovariectomy model, which may not fully capture complex human postmenopausal biology. The abstract does not report the total animal sample size (n), specific dosages, treatment durations, or precise quantitative values and variance metrics for most endpoints.
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- contradicts Cholesterol levels rise in perimenopause because the liver continues producing cholesterol to synthesize steroid hormones after the ovaries stop responding.