Incidences of breast cancer throughout long-term hormone replacement therapy

Xiaoyao San attenuates hepatic steatosis through estrogen receptor α pathway in ovariectomized ApoE-/- mice

ETHNOPHARMACOLOGICAL RELEVANCE

Xiaoyao San (XYS) is a famous prescription in traditional Chinese medicine, which is used in the treatment of "liver depression and spleen deficiency" syndrome. It is often used clinically to treat chronic hepatitis, liver cirrhosis, various symptoms of postmenopausal women, especially mental disorders and digestive system diseases. However, the effect of XYS on hepatic steatosis in postmenopausal women remains unclear. In this research, we investigated the effects of XYS on hepatic steatosis in ovariectomized (OVX) apolipoprotein E knockout (ApoE-/-) mice, as well as the molecular mechanisms in vitro and in vivo.

MATERIALS AND METHODS

Fifty female ApoE-/- mice were divided into 5 groups: control group (Sham), model group (OVX), OVX + β-estradiol (E2, 0.4 mg/kg) group, OVX + XYS (13.0 g/kg) group, and OVX + XYS (6.5 g/kg) group. The control group received a standard diet, while the other groups received a high-fat diet (HFD). The hepatic pathologies of the mice were examined with Oil red O staining and HE staining after 12 week treatment. Blood and liver variables were determined enzymatically. Transmission electron microscopy was used to examine the ultrastructure of hepatocytes. The expression of estrogen receptor α (ERα) and lipid metabolism genes was analyzed by real-time PCR and/or Western blot. In in vitro studies, we investigated the effect of XYS-medicated serum on the expression and activity of ERα in L02 cells by immunofluorescence and luciferase reporter assays, and examined the protection of XYS-medicated serum against free fatty acid (FFA)-induced steatosis of L02 cells. Intracellular lipid accumulation were measured by Oil red O staining and Nile red staining assay. Finally, the influence of ICI 182,780, a specific antagonist of ERα, on the protective effect of XYS-medicated serum on FFA-induced steatosis of L02 cells was investigated.

RESULTS

Treatment of Ovx/ApoE-/- mice with XYS significantly decreased HFD-induced increases in hepatic steatosis and triglyceride (TG) content, accompanied by inhibition of liver X receptor α (LXRα), sterol regulatory element binding protein (SREBP)-1c and its target lipogenic genes transcription. Similarly, XYS-medicated serum reduced the size and number of lipid droplets and the cellular TG content in FFA-induced L02 cells. In addition, XYS significantly increased the ERα expression in hepatocytes in vivo and in vitro and enhanced the transcriptional activity of ERα promoter in L02 cells. And these effects could be partly reversed by the antiestrogen ICI 182,780.

CONCLUSIONS

These findings suggest that XYS has an estrogen-like effect and inhibits steatosis in postmenopausal animal models by reducing the expression of genes related to TG synthesis through ERα pathway.

Effect of Chaihushugan San on expression of the Raf/mitogen-activated protein kinase/extracellular signal-regulated kinase pathway in the hippocampi of perimenopausal rats induced by immobilization stress

OBJECTIVE

We wished to study the impact of Chaihushugan San (CSS) on the behavior of perimenopausal rats with liver-Qi stagnation (LQS) and to investigate the effect of CSS on signal transduction of the Raf/mitogen-activated protein kinase (MEK)/ extracellular signal-regulated kinase (ERK) cascade in the hippocampi of rats induced by immobilization.

METHODS

Twenty 52-week-old female rats were divided into two groups by the random number table method: model control group (MCG) and CSS group (CSSG), with 10 rats in each group. Ten-week-old female rats were used as the normal control group (NCG). CSS effects were assessed using rats exposed to immobilization stress by measuring body weight and sucrose consumption, serum hormone levels, and observing performance in the open field test (OFT). Molecular mechanisms were examined by measuring the effect of CSS on expression of Raf1, MEK1/2 and ERK1/2 mRNA in hippocampi using quantitative real-time polymerase chain reaction and by measuring levels of these proteins and related phospho-proteins using Western blotting.

RESULTS

Perimenopausal rats with LQS had decreased locomotor activity; reduced sucrose consumption; and increased serum levels of corticotropin releasing hormone (CRH) and corticosterone (CORT). Activation of hippocampal Raf/MEK/ERK cascade was suppressed significantly in the MCG, and activation was increased after 21 days of CSS treatment.

CONCLUSION

CSS has significant effects upon relief of the symptoms of LQS in immobilization-induced rats. The mechanism underlying this action might (at least in part) be mediated by reversal of disruption of the Raf/MEK/ERK pathway.