Cinnabar-induced subchronic renal injury is associated with increased apoptosis in rats

Protective Effects of Low-Dose Alcohol against Acute Stress-Induced Renal Injury in Rats: Involvement of CYP4A/20-HETE and LTB4/BLT1 Pathways

Low-dose alcohol possesses multiple bioactivities. Accordingly, we investigated the protective effect and related molecular mechanism of low-dose alcohol against acute stress- (AS-) induced renal injury. Herein, exhaustive swimming for 15 min combined with restraint stress for 3 h was performed to establish a rat acute stress model, which was verified by an open field test. Evaluation of renal function (blood creatinine and urea nitrogen), urine test (urine leukocyte esterase and urine occult blood), renal histopathology, oxidative stress, inflammation, and apoptosis was performed. The key indicators of the cytochrome P450 (CYP) 4A1/20-hydroxystilbenetetraenoic acid (20-HETE) pathway, cyclooxygenase (COX)/prostaglandin E₂ (PGE₂) pathway, and leukotriene B₄ (LTB₄)/leukotriene B₄ receptor 1 (BLT1) pathway were measured by real-time PCR and ELISA. We found that low-dose alcohol (0.05 g/kg, i.p.) ameliorated AS-induced renal dysfunction and histological damage. Low-dose alcohol also attenuated AS-induced oxidative stress and inflammation, presenting as reduced malondialdehyde and hydrogen peroxide formation, increased superoxide dismutase and glutathione activity, and decreased myeloperoxidase, interleukin-6, interleukin-1β, and monocyte chemoattractant protein-1 levels (P < 0.05). Moreover, low-dose alcohol alleviated AS-induced apoptosis by downregulating Bax and cleaved caspase 3 protein expression and reduced numbers of terminal deoxynucleotidyl transferase-mediated dUTP nick-end label-positive cells (P < 0.01). Correlation analysis indicated that 20-HETE was strongly correlated with oxidative stress, while LTB₄ was strongly correlated with inflammation. Low-dose alcohol inhibited AS-induced increases in CYP4A1, CYP4A2, CYP4A3, CYP4A8, and BLT1 mRNA levels and LTB₄ and 20-HETE content (P < 0.01). Interestingly, low-dose alcohol had no effect on COX1 or COX2 mRNA expression or the concentration of PGE₂. Furthermore, low-dose alcohol reduced calcium-independent phospholipase A₂ mRNA expression, but did not affect secreted phospholipase A₂ or cytosolic phospholipase A₂ mRNA expression. Together, these results indicate that low-dose alcohol ameliorated AS-induced renal injury by inhibiting CYP4A/20-HETE and LTB₄/BLT1 pathways, but not the COX/PGE₂ pathway.

Cinnabar protects serum-nutrient starvation induced apoptosis by improving intracellular oxidative stress and inhibiting the expression of CHOP and PERK

Cinnabar has been used for treatment of various disorders for thousands of years. The medical use of cinnabar, however, has been controversial because of its heavy metal mercury content. A large quantity of studies indicate that the toxicity of cinnabar is far below other inorganic or organic mercury-containing compounds. Yet, the underlying molecular basis has remained unresolved. Here, we investigated the beneficial effects of cinnabar on serum-nutrient starvation-elicited cell injury. Our findings showed that treatment of human renal proximal tubular cells (HK-2) with 4 nM cinnabar effectively inhibited nutrient deprivation induced apoptosis, reduced intracellular reactive oxygen species generation and increased GSH content, which was contrary to the exacerbated apoptotic cell death and oxidative stress in cells treated with HgCl₂ at equal mercury concentration. In addition, cinnabar exerted robust antioxidative and antiapoptotic effects in cells under dual challenges of nutrient deprivation and treatment of H₂O₂. The protein expression levels of both CHOP and PERK were remarkably down-regulated in the cells treated with cinnabar compared to the control cells or cells treated with HgCl₂. Overall, our data indicates that cinnabar at low concentration exerts anti-oxidative stress and anti-apoptosis effects by inhibiting the expression of the endoplasmic reticulum stress pathway proteins CHOP and PERK.

Protective Effect of An-Gong-Niu-Huang Wan Pre-treatment Against Experimental Cerebral Ischemia Injury via Regulating GSK-3β/HO-1 Pathway

An-Gong-Niu-Huang Wan (AGNHW), a famous formula in traditional Chinese medicine, has been clinically used for centuries for treating cerebral diseases, but the protective effects of pre-treatment with AGNHW on cerebral ischemia have not yet been reported. The present study aimed to test such protective effects and elucidate the underlying mechanisms on cerebral ischemia in rats by phenotypic approaches (i.e. including the neurological functional score, cerebral infarct area, neuron apoptosis, and brain oxidative stress status) and target-based approaches (i.e. involving the GSK-3β/HO-1 pathway). AGNHW was administered orally at the doses of 386.26, 772.52, and 1545.04 mg/kg respectively for 7 days to male Sprague-Dawley rats and then cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) for 1.5 h. Pre-treatment with AGNHW significantly ameliorated ischemic damage to the brain in a dose-dependent manner, including reduction of the neurological deficit score and infarct area. AGNHW pre-treatment increased the number of Nissl⁺ cells, NeuN⁺ and DCX⁺ cells, and decreased the number of Tunel⁺ cells. Moreover, AGNHW reversed the up-regulation of ROS and MDA induced by cerebral ischemia. AGNHW pre-treatment increased the expression of p-GSK-3β(Ser9)/GSK-3β (glycogen synthase kinase-3β) ratio and heme oxygenase-1 (HO-1). These results firstly revealed that short-term pre-treatment of AGNHW could significantly protect the rats from injury caused by cerebral ischemia-reperfusion, which support further clinical studies for disease prevention. The in vivo protective effect of AGNWH pre-treatment could be associated with its antioxidant properties by the activation of GSK-3β-mediated HO-1 pathway.

The Herbal Constituents in An-Gong-Niu-Huang Wan (AGNH) Protect against Cinnabar- and Realgar-Induced Hepatorenal Toxicity and Accumulations of Mercury and Arsenic in Mice

An-Gong-Niu-Huang Wan (AGNH) has been a well-known cinnabar- and realgar-containing compound recipe for cerebral diseases. Unfortunately, its clinical practice is often restrained by the specific hepatorenal toxicity of cinnabar and realgar (C + R). In previous research studies, we have found that the antioxidative and anti-inflammatory effects of its herbal constituents could mitigate the risks from the toxicity. The underlying detoxification mechanisms are still unsolved. The present study investigated the protective effects of AGNH's herbal constituents on hepatorenal injury induced by C + R. For the mice treated with C + R, the increased expression levels of sensitive biomarkers of metal exposure and hepatorenal toxicity, including metallothionein (MT) in both hepatorenal tissues and kidney induced molecule-1 (KIM-1) in the kidney, were simultaneously reduced when C + R coadministered with other herbal medicines. In addition, the contents of trivalent As (As^III), pentavalent As (As^v), and mercury (Hg) in hepatorenal tissues of mice were also significantly reduced benefiting from the herbal constituents in AGNH. Further mechanism studies showed that the herbal constituents in AGNH could downregulate the expressions of uptake transporters (AQP9 and OAT1) and upregulate the expressions of efflux transporters (P-gp, MRP2, and MRP4) in mice intoxicated by C + R. Our results suggested that AGNH's herbal constituents protect the body against C + R-induced hepatorenal toxicity and accumulations of Hg and As, which could be associated with the reestablishment of heavy metal homeostasis and the detoxification system.

Nephrotoxicity of Herbal Medicine and Its Prevention

Herbal medicine (HM) has been widely used to treat diseases for thousands of years and has greatly contributed to the health of human beings. Many new drugs have been developed from HM, such as artemisinin. However, artemisinin has adverse effects, such as renal toxicity. In 1993, a study conducted in Belgium reported for the first time that the root extracts of Aristolochia obliqua S. M. Hwang led to progressive interstitial renal fibrosis. The nephrotoxicity of HM has attracted worldwide attention. More than 100 kinds of HM induce renal toxicity, including some herbs, animal HMs, and minerals. This paper aimed to summarize the HM compounds that cause nephrotoxicity, the mechanisms underlying the toxicity of these compounds, biomarkers of renal injury, and prevention strategies. These findings provide a basis for follow-up studies on the prevention and treatment of HM nephrotoxicity.

Neuroprotective Effects and Hepatorenal Toxicity of Angong Niuhuang Wan Against Ischemia-Reperfusion Brain Injury in Rats

Angong Niuhuang Wan (AGNHW) is a classic prescription in traditional Chinese medicine (TCM) used for stroke treatment, but its efficacies remain to be confirmed. With its arsenic- and mercury-containing materials, the application of AGNHW raises great safety concerns. Herein, we aim to explore the neuropharmacological effects against cerebral ischemia-reperfusion injury and evaluate the toxicological effects of AGNHW for better use. Male SD rats were subjected to 2 h of middle cerebral artery occlusion (MCAO) and following 22 h of reperfusion. AGNHW (257 mg/kg, 1× AGNHW) were orally administered for pharmacological effects and 257, 514, and 1,028 mg/kg (equivalent to 1×, 2×, 4× AGNHW) were used for the toxicological study. The results revealed that AGNHW treatment reduced the infarct size and protected the blood-brain barrier (BBB) integrity in the MCAO rat ischemic stroke model. AGNHW treatment up-regulated bcl-2 expression and down-regulated the expressions of Bax, p47_phox, inducible nitric oxide synthase (iNOS), and 3-nitrotyrosine (3-NT), and inhibited the expressions and activities of matrix metalloproteinase-2 (MMP-2), MMP-9, and reserved tight junction protein zonula occludens-1 (ZO-1) and claudin-5 in the ischemic brains. These results indicated that the neuroprotective mechanisms of AGNHW could be associated with its antioxidant properties by inhibiting oxidative/nitrative stress-mediated MMP activation and protecting tight junction proteins in the ischemic brains. Administration of 1× AGNHW for 7 days would not induce the accumulation of mercury in blood, liver, and kidney at day 14. Administration of 2× AGNHW and 4× AGNHW for 7 days increased the level of mercury in the kidney. For arsenic level, administration of 1× AGNHW for 7 days would increase the level of arsenic in the liver and blood without increase of arsenic in the kidney at day 14. Administration of 2× AGNHW and 4× AGNHW for 7 days would further increase the level of arsenic in the liver and blood. There is no influence on body weight, organ index, histological structures, and renal and liver functions. These results suggest that short-term treatment of AGNHW within 1 week should be safe and has neuroprotective effects against cerebral ischemia-reperfusion injury.

Dexmedetomidine Ameliorates Acute Stress-Induced Kidney Injury by Attenuating Oxidative Stress and Apoptosis through Inhibition of the ROS/JNK Signaling Pathway

Acute stress induces tissue damage through excessive oxidative stress. Dexmedetomidine (DEX) reportedly has an antioxidant effect. However, protective roles and related potential molecular mechanisms of DEX against kidney injury induced by acute stress are unknown. Herein, rats were forced to swim 15 min followed by restraint stress for 3 h with/without DEX (30 μg/kg). Successful model establishment was validated by an open-field test. Assessment of renal function (creatinine, urea nitrogen), histopathology, oxidative stress (malondialdehyde, glutathione, and superoxide dismutase), and apoptosis (transferase-mediated dUTP nick end labeling) was performed. Localization of apoptosis was determined by immunohistochemistry of cleaved caspase 3 protein. In addition, key proteins of the death receptor-mediated pathway, mitochondrial pathway, endoplasmic reticulum stress (ERS) pathway, and ROS/JNK signaling pathway were measured by Western blot. We found that DEX significantly improved renal dysfunction, ameliorated kidney injury, reduced oxidative stress, and alleviated apoptosis. DEX also inhibited the release of norepinephrine (NE), decreased the production of reactive oxygen species (ROS), and inhibited JNK phosphorylation. Additionally, DEX downregulated the expression of Bax, cytochrome C, cleaved caspase 9, and cleaved caspase 3 proteins in mitochondria-dependent pathways. In summary, DEX protects against acute stress-induced kidney injury in rats by reducing oxidative stress and apoptosis via inhibition of the ROS/JNK pathway.