AIMS: To assess the estradiol induced changes in plasma ceruloplasmin concentration on exposure of the rats to acute stress.
SETTINGS AND DESIGN: Acute stress was induced by forcing the rats to swim till exhaustion. The rats were overiectomised bilaterally to remove the primary source of sex hormones. And hormone replacement was done later.
MATERIAL AND METHODS: Wistar albino female rats were used. Acute stress was induced before overiectomy, following recovery from surgery, and again after Estradiol Valerate injection (for 10 days) in same group of rats. The plasma ceruloplasmin was estimated immediately after stress during each stage--that is preoperative control, stressed control, after overiectomy and then following treatment with Estradiol Valerate.
STATISTICAL ANALYSIS USED: Paired sample T test was applied to analyze the findings.
RESULTS: We found lowest ceruloplasmin level after stress in overiectomised animals, while on substitution of estradiol the trend appeared to be reversed.
CONCLUSION: The result suggested a direct effect of estrogen on hepatic ceruloplasmin production/release and this could account for some of the beneficial effects of hormone replacement therapy.
METHODS: Reverse-transcription-polymerase chain reaction was employed to measure the expression of plasmacytoma variant translocation 1 (PVT1), microRNAs (miRNAs), and SIRT3, and the dual-luciferase assay was used to determine their interaction. Electron microscopy observes autophagosomes, green fluorescent protein-microtubule-associated protein 1 light chain 3 (GFP-LC3) staining, and immunoblot analysis with antibodies against LC3,beclin-1, and P62 were conducted to measure autophagy. Cellular senescence was determined using immunoblot analysis with anti-phosphorylated retinoblastoma and senescence-associated β-galactosidase staining.
RESULTS: Women with higher estrogen levels (during the 10-13th day of the menstrual cycle or premenopausal) exhibit markedly higher serum levels of PVT1 than women with lower estrogen levels (during the menstrual period or postmenopausal). The dual-luciferase assay showed that PVT1 acts as a sponge for miR-31, and miR-31 binds to its target gene, SIRT3. The 17β-E2 treatment increased the expression of PVT1 and SIRT3 and downregulated miR-31 expression in human umbilical vein endothelial cells (HUVECs). Consistently, PVT1 overexpression suppresses miR-31 expression, promotes 17β-E2-induced autophagy, and inhibits H2O2-induced senescence. miR-31 inhibitor increases SIRT3 expression and leads to activation of 17β-E2-induced autophagy and suppression of H2O2-induced senescence.
CONCLUSION: Our findings demonstrated that 17β-E2 upregulates PVT1 gene expression and PVT1 functions as a sponge to inhibit miR-31, resulting in the upregulation of SIRT3 expression and activation of autophagy and subsequent inhibition of H2O2-induced senescence in HUVECs.