Sarco/endoplasmic reticulum Ca2+ ATPase (SERCA)-mediated ER stress crosstalk with autophagy is involved in tris(2-chloroethyl) phosphate stress-induced cardiac fibrosis.

Excessive organophosphate flame retardant (OPFR) use in consumer products has been reported to increase human disease susceptibility. However, the adverse effects of tris(2-chloroethyl) phosphate (TCEP) (a chlorinated alkyl OPFR) on the heart remain unknown. In this study, we tested whether cardiac fibrosis occurred in animal models of TCEP (10 mg/kg b.w./day) administered continuously by gavage for 30 days and evaluated the specific role of sarco/endoplasmic reticulum Ca2+ ATPase (SERCA). First, we confirmed that TCEP could trigger cardiac fibrosis by histopathological observation and cardiac fibrosis markers. We further verified that cardiac fibrosis occurred in animal models of TCEP exposure accompanied by SERCA2a, SERCA2b and SERCA2c downregulation. Notably, inductively coupled plasma-mass spectrometry (ICP-MS) analysis revealed that the cardiac concentrations of Ca2+ increased by 45.3% after TCEP exposure. Using 4-Isopropoxy-N-(2-methylquinolin-8-yl)benzamide (CDN1163, a small molecule SERCA activator), we observed that Ca2+ overload and subsequent cardiac fibrosis caused by TCEP were both alleviated. Simultaneously, the protein levels of endoplasmic reticulum (ER) markers (protein kinase R-like endoplasmic reticulum kinase (PERK), inositol requiring protein 1α (IRE1α), eukaryotic initiation factor 2 α (eIF2α)) were upregulated by TCEP, which could be abrogated by CDN1163 pretreatment. Furthermore, we observed that CDN1163 supplementation prevented overactive autophagy induced by TCEP in the heart. Mechanistically, TCEP could lead to Ca2+ overload by inhibiting the expression of SERCA, thereby triggering ER stress and overactive autophagy, eventually resulting in cardiac fibrosis. Together, our results suggest that the Ca2+ overload/ER stress/autophagy axis can act as a driver of cardiotoxicity induced by TCEP.

Nrf2 signalling pathway and autophagy impact on the preventive effect of green tea extract against alcohol-induced liver injury.

OBJECTIVES: To explore the potential molecular mechanism underlying the effect of green tea extract (TE), rich in tea polyphenols (TPs), on improving alcohol-induced liver injury. METHODS: Mice were intragastrically treated with 50% (v/v) alcohol administration (15 ml/kg BW) with or without three doses of TE (50, 120 and 300 mg TPs/kg BW) daily for 4 weeks, and biological changes were tested. KEY FINDINGS: The TE improved the functional and histological situations in the liver of the mice accepted alcohol administration, including enzymes for alcohol metabolism, oxidative stress and lipid accumulation. Interestingly, the TE increased the nuclear translocation of nuclear factor erythroid-2-related factor 2 (Nrf2), with the decreasing expression of kelch-like ECH-associated protein 1 (Keap1), indicating the association between the effect of TE with Nrf2-mediated antioxidant signalling. Moreover, the TE restored the activity of autophagy, showing as lifted Beclin-1 expression, LC3B-II/LC3B-I ratio, and decreased p62 expression. Importantly, all these effects were dose-dependent. CONCLUSIONS: These findings provide a new notion for the first time that the TE preventing against alcohol-induced liver injury is closely related to accelerated metabolism of alcohol and relieved oxidative stress, which is associated with Nrf2 signalling activation and autophagy restoration, thus the reduction of lipid accumulation in liver.

Preventive effects of low molecular mass potassium alginate extracted from brown algae on DOCA salt-induced hypertension in rats.

Available evidence indicates that brown algae may be beneficial for the treatment of high blood pressure. Our recent study demonstrated that low molecular mass potassium alginate (L-PA), one of the major polysaccharides extracted from brown algae, decreased systolic blood pressure (SBP) in spontaneous hypertensive rats. The present study investigated the effects of L-PA on deoxycorticosterone acetate (DOCA) salt-induced hypertension in rats. Hypertension was induced by biweekly subcutaneous injections of 50mg/kg DOCA plus 1% NaCl in drinking water. The control group received saline injections. L-PA (250 or 500 mg/kg), KCl (239 mg/kg), or volume-matched solvent was administered orally once daily for 30 days. DOCA salt administration significantly increased SBP, sodium excretion, serum sodium content, circulating plasma volume (CPV), plasma atrial natriuretic peptide (ANP) content, heart and renal weight indices, and mortality and decreased plasma aldosterone (ALD) and serum potassium levels in the vehicle-treated DOCA salt group compared with the control group. However, L-PA dose-dependently normalized the above changes induced by DOCA salt, with the exception of further increasing sodium excretion, while KCl did not affect the changes caused by DOCA salt, with the exception of slightly ameliorating hypokalemia and mortality. These findings suggest that L-PA may offer a novel form of potassium supplementation with greater antihypertensive and sodium excretion actions than KCl and may likely be beneficial for the primary prevention and treatment of hypertension and its cardiovascular sequelae.

[Antihypertensive effect and pharmacokinetics of low molecular mass potassium alginate].

OBJECTIVE: To investigate the effect of low molecular weight potassium alginate (L-PA) on blood pressures in spontaneously hypertensive rats (SHRs) and its pharmacokinetics characteristics in mice. METHODS: The systolic blood pressure (SBP) was measured by tail-cuff method in conscious SHRs. Forty rats were randomly assigned to the following five groups: control, hydrochlorothiazide (HCT, 6.25 mg/kg), L-PA in low, middle or high dose groups (100, 250, 500 mg/kg). SHRs were intragastrically (i. g.) administrated once daily for 28 days. The SBP was measured once weekly during drug treatment, and 3 and 6 days after drug with drawal. KM mice were i. g. administered with 100 mg/kg (74 MBq/kg) of 3H-L-PA. Ten microl blood samples were obtained from the tail vein at 2, 5, 10, 20, 30 min and 1, 2, 4, 6, 12, 24, 48, 72, 96, 120 or 144 h after drug administration for measuring radioactivities. Pharmacokinetics parameters of the oral administration of L-PA were analysed with DAS 2.0 software. RESULTS: Twenty-one or 28 days after administration, the rats in the groups treated with HCT or L-PA at 100, 250 or 500 mg/kg had a significant decrease in SBP (P<0.01 vs control group). Three or 6 days after drug withdrawal, the antihypertensive effect of HCT disappeared (P>0.05), whereas the rats treated with 250 or 500 mg/kg L-PA still had lower SBP than the controls (P<0.01). The L-PA at a dose of 100 mg/kg also led to a significant decrease in SBP 3 days after drug withdrawal (P<0.05). The pharmacokinetics of L-PA (i. g.) was consistent with a two-compartment model, with 2.76 h of absorption half-life (t1/2, Ka), 42. 30 h of distributional half-life (t1/2alpha), 42. 31 h of elimination half-life (t1/2beta), and 36.28 h of terminal phase elimination half-life (t1/2z). CONCLUSION: Oral administration of L-PA has significant anti-hypertensive effect, which can be maintained to 6 days after drug withdrawal. The sustaining anti-hypertensive effect of L-PA is probably associated with its slow elimination in vivo.

Z-ligustilide extracted from Radix Angelica Sinensis decreased platelet aggregation induced by ADP ex vivo and arterio-venous shunt thrombosis in vivo in rats.

Antithrombotic therapy has become an important goal for the treatment of ischemic disorders such as cerebral ischemia. Our recent studies found that Z-ligustilide (LIG), a characterized 3-n-alkylphthalide constituent of Radix Angelica sinensis essential oil, exerted significant neuroprotection against cerebral ischemic damage in several animal models. The present study evaluated the antithrombotic activity of LIG and its effect on platelet aggregation and coagulation time. LIG (10 or 40 mg/kg) was intragastrically administered to rats once daily for 3 days. Our results showed that LIG significantly and dose-dependently reduced arterial thrombus weight in an arteriovenous shunt thrombosis in rats and platelet aggregation induced by adenosine diphosphate in rats ex vivo. Meanwhile, LIG at 10 or 40 mg/kg had no significant effect on coagulation time, including activated partial thromboplastin time and prothrombin time, in rats ex vivo. The present study demonstrated for the first time that LIG may exert efficient antithrombotic activity through inhibition of platelet aggregation, without effecting coagulation time of peripheral blood. These data, together with the previously reported neuroprotective effects of LIG on cerebral ischemia, suggest that the antithrombotic activity of LIG may contribute to its potential for the treatment of ischemic diseases, including ischemic stroke.