Timing of hormone therapy and its association with cardiovascular risk and metabolic parameters in 4-vinylcyclohexene diepoxide-induced primary ovarian insufficiency mouse model

Abstract

Objective To evaluate the effects of various initiation time points and durations of hormone therapy (HT) on cardiovascular and metabolic parameters of premenarche, primary ovarian insufficiency (POI) mouse model, induced by 4-vinylcyclohexene diepoxide. Methods A total of 50 mice at 4 weeks of age were developed into POI mouse model, further randomly categorized into 5 groups: control group without any intervention; no HT group with only high-fat diet (NT); group 1 with delayed estradiol treatment (T1); group 2 with on-time, continuous estradiol treatment (T2); and group 3 with on-time estradiol treatment but early stop (T3). Cardiovascular risk and metabolic parameters were measured. Results Presenting with similar body weights, blood glucose levels of T1, T2, and T3 were all significantly lower than NT (p < .001). Serum total cholesterol and insulin were also significantly lower in all HT groups than in NT, especially in T2 (p < .001). For serum low-density lipoprotein-cholesterol, only T2 resulted in the statically lower level than those of NT, T1, and T3 (p < .001). Aortic thickness was significantly increased with aggravated fibrotic change of the intima in NT, and such consequence was significantly ameliorated in HT groups, mostly lowered in T2 (p < .05). Last, serum pro-inflammatory cytokines were significantly low in the HT groups than in NT, especially in T2 with the lowest level (p < .05). Conclusions On-time, continuous E2 treatment immediately after a biologic estrogen deprivation event significantly reduced metabolic and cardiovascular risks in young, pre-menarche female mouse models of POI, confirming decreased serum levels of pro-inflammatory cytokines.