Effect of tetramethylpyrazine and hyperlipidemia on hepcidin homeostasis in mice.

Iron homeostasis is strictly regulated in mammals, and disordered iron metabolism is recognized as a risk factor for various diseases, including cardiovascular disease. The hepcidin­ferroportin axis is the key signaling mechanism that controls systemic iron homeostasis. Increased serum hepcidin is associated with multiple types of cancer and atherosclerosis (AS), and therapeutics that decrease hepcidin levels have been proposed to treat these diseases. However, the effects of abnormal circulating hepcidin on hyperlipidemia remain unexploited. The natural compound tetramethylpyrazine (TMP) has been reported to have therapeutic effects on cardiovascular diseases, whereas the mechanisms involved remain incompletely understood. Thus, the effects of TMP on the expression of hepcidin in hyperlipidemic mice were investigated and the mechanisms involved were explored. Hyperlipidemia increased serum hepcidin, which was inhibited by TMP intervention. The results also indicated that TMP may decrease hepcidin expression via inhibition of Stat3 signaling. These findings suggest a promising rationale to prevent and hyperlidemia by targeting hepcidin or its upstream regulators, and highlight the potential application of natural compounds in treating hepcidin disorder­associated diseases.

Leptin regulates energy intake but fails to facilitate hibernation in fattening Daurian ground squirrels (Spermophilus dauricus).

Body fat storage before hibernation affects the timing of immergence in Daurian ground squirrels (Spermophilus dauricus). Leptin is an adipose signal and plays vital role in energy homeostasis mainly by action in brain. To test the hypothesis that leptin plays a role in facilitating the process of hibernation, squirrels were administrated with recombinant murine leptin (1µg/day) through intracerebroventricular (ICV) injection for 12 days during fattening. From day 7 to 12, animals were moved into a cold room (5±1°C) with constant darkness which functioned as hibernaculum. Energy intake, body mass and core body temperature (Tb) were continuously monitored throughout the course of experiment. Resting metabolic rate (RMR) was measured under both warm and cold conditions. At the end of leptin administration, we measured the serum concentration of hormones related to energy regulation, mRNA expression of hypothalamic neuropeptides and uncoupling protein 1 (UCP1) levels in brown adipose tissue (BAT). Our results showed that during leptin administration, the cumulative food intake and increase of body mass were suppressed while Tb and RMR were unaltered. The proportion of torpid squirrels was not different between two groups. At the end of leptin administration, the expressions of hypothalamic neuropeptide Y and agouti gene-related protein were suppressed. There were no differences in UCP1 mRNA expression or protein content in BAT between groups. Our data suggest that leptin can affect energy intake via hypothalamic neuropeptides, but is not involved in the initiation of hibernation in fattening Daurian ground squirrels.

Anti-inflammatory effects of tanshinone IIA on atherosclerostic vessels of ovariectomized ApoE mice are mediated by estrogen receptor activation and through the ERK signaling pathway.

AIMS: Estrogen plays a protective role in atherosclerosis. Our preliminary work demonstrated that the active conformation of Tanshinone IIA(TanIIA) is similar to the 17ß-estradiol and it can bind to the estrogen receptor. Here, we hypothesized that Tanshinone IIA might have anti-inflammatory and anti-oxidative effects in atherosclerosis, mediated through estrogen receptor activation. METHODS: Subjects for this study were 120 apoE(-/-) female mice and 20 C57/BL female mice. The apoE(-/-) mice were ovariectomized (OVX) and the C57/BL mice were sham ovariectomized. The sham OVX mice were maintained on a normal diet (NOR) group. The OVX apoE(-/-) mice were fed a high fat diet and randomly divided into 6 groups: Model (MOD) group which was fed a high fat diet only, E2 group were given estrogen (E2) 0.13 mg/kg/d; E2+ICI group were given E2:0.13 mg/kg/d and ICI182780:65 mg/kg/m; TLD group (TanIIA low dose) were given TanIIA: 30 mg/kg/d; THD group (TanIIA high dose) were given TanIIA:60 mg/kg/d; and TLD+ICI group were given TanIIA 30 mg/kg/d and ICI182780 65 mg/kg/m. After three months of treatment, the aorta and the blood of the mice from each group was collected. The aorta were used for testing the lipid deposition by using hematoxylin and eosin(HE) and oil red O staining and for testing the expression of p-ERK1/2 by Western blot. The blood was used for testing the serum cholesterol, superoxide dismutase (SOD), methane dicarboxylic aldehyde (MDA), nuclear factor kappa (NF-κB), soluble intercellular cell adhesion molecule-1 (sICAM-1), activating protein-1 (AP-1), E-selectin and 17ß-estradiol in serum. RESULTS: Tanshinone IIA significantly reduced the lipid deposition in aorta, decreased the levels of total cholesterol (TC), triglyceride (TG), low density lipoprotein (LDL), very low density lipoprotein (VLDL), MDA, NF-κB, sICAM-1, AP-1, and E-selectin in serum but increased the levels of high density lipoprotein (HDL) and SOD in serum. Tanshinone IIA also suppressed the expression of p-ERK1/2. Tanshinone IIA had no effect of level of serum 17ß-estradiol levels. All of the effects of Tanshinone IIA were similar to estrogen and were inhibited by the estrogen receptor antagonist ICI182780. CONCLUSION: Tanshinone IIA may play an anti-inflammatory and anti-oxidative stress role in OVX atherosclerotic apoE(-/-) mice by activating the estrogen receptor through the ERK signaling pathway. Therefore, Tanshinone IIA, as a phytoestrogen, could be used for estrogen replacement therapy for cardiovascular disease of postmenopausal women.

[The estrogen-like protective effect of ginsenoside Rb3 on oxidative stress and dysfunction of endothelial cells induced by oxidized low-density lipoprotein].

Ginsenoside Rb3 (GRb3) is one of the main components in plasma of Panax quinquefolius Saponin of stem and leaf (PQS), which can be into human plasma. Previous studies have found PQS has estrogen-like vascular protective effects. In the present study, we investigated the estrogen-like protective effect of GRb3 on oxidative stress and dysfunction of endothelial cells induced by oxidized low-density lipoprotein. The activities of SOD, NOS and the contents of MDA in the cell lysate were examined by enzyme method or spectrophotometry. The NO and ET-1 concentrations in the cell culture supernatant were measured by ELISA method. The iNOS and eNOS mRNA expression were measured by real time RT-PCR, while the phosphorylation levels of Akt was measured by Western blotting. The results showed that GRb3 could enhance the activity of SOD, reduce the content of MDA, increase the level of NOS, NO, ET-1 and iNOS mRNA expression while decrease the eNOS mRNA expression and the phosphorylation level of Akt. These effects were blocked by estrogen receptor antagonist ICI182780. GRb3 can play a role in protecting vascular endothelial cells by estrogen receptors, the protective mechanism is similar to 17-ß estrodiol.