Roles of Cyt-c/Caspase-9/Caspase-3/Bax/Bcl-2 pathway in Cd-induced testicular injury in rats and the protective effect of quercetin.

Cadmium (Cd) exposure causes oxidative damage to mitochondria, which would adversely affect rat testicular tissue. Quercetin (Que) is a natural antioxidant with anti-inflammatory, antioxidant and anti-apoptotic effects. However, the mechanism by which Que inhibits Cd-induced apoptosis of testicular cells remains unclear. The purpose of this study was to investigate the role of mitochondrial apoptosis pathway (Cyt-c/Caspase-9/Caspase-3/Bax/Bcl-2 pathway) in inhibiting Cd-induced apoptosis of testicular cells by Que. We used SD rats to simulate Cd chloride exposure by treating all sides of the rats with CdCl2 and/or Que. The levels of GSH and MDA in rat testis were detected using reagent kits. The effects of CdCl2 and/or Que on tissue damage, apoptosis, and gene and protein expression of the Cyt-c/Caspase-9/Caspase-3/Bax/Bcl-2 pathway in rat testis were examined by HE, TUNEL, RNA extraction and reverse-transcriptase polymerase chain reaction (RT-PCR), and Western blot (Wb). The results show that Cd significantly increased the contents of GSH and MDA in rat testis (P < 0.01); conversely, Que significantly reduced the contents of GSH and MDA (P < 0.01). Cd inflicted damage to testicular tissue, and Que addition significantly reduced the damage. Cd increased the number of apoptosis of testicle cells, and Que inhibited testicle-cell apoptosis. In addition, the results of reverse transcription PCR and Wb assays confirmed that, as expected, Cd increased the expression levels of Cyt-c, Caspase-9, Caspase-3, and Bax mRNAs as well as proteins. And at the same time decreased the expression of the anti-apoptotic factor Bcl-2 in the cells. Surprisingly, these effects were reversed when Que was added. Therefore, Que can play an antioxidant and anti-apoptotic role in reducing the testicular tissue damage caused by Cd exposure. This provides a conceptual basis for the later development and utilization of Que as well as the prevention and treatment of tissue damage caused by Cd exposure.

Protective effect of quercetin on cadmium-induced kidney apoptosis in rats based on PERK signaling pathway.

BACKGROUND: Cadmium (Cd) is a highly toxic environmental pollutant that can enter the body through bioaccumulation. The kidney is an important target organ for Cd poisoning. Quercetin (Que) is a natural flavonoid compound with free radical scavenging and antioxidant properties. Previous studies showed that Que can alleviate kidney damage caused by Cd poisoning in rats, but the specific mechanism is still unclear. METHODS: Twenty-four male Sprague-Dawley (SD) rats were divided into four groups: normal saline-treated control group, Cd group treated by intraperitoneal injection of 2 mg/kg b.w. CdCl2, Cd + Que group treated by intraperitoneal injection of 2 mg/kg b.w. CdCl2 and 100 mg/kg b.w. Que, and Que group treated by 100 mg/kg b.w. Que. Four weeks later, the rats were anesthetized with diethyl ether, and blood was taken intravenously. The rats were executed with their necks cut off, and the kidneys were removed. Body weight, kidney organ weight, and glutathione (GSH) and malondialdehyde (MDA) levels were measured. The structure of kidney tissue was observed by hematoxylin and eosin staining, kidney cell apoptosis was detected by TUNEL assay, and the mRNA expression levels of genes related to the PERK signaling pathway were analyzed by RT-PCR. RESULTS: Compared with the control group, the Cd-treated group exhibited a significant decrease in body weight (P < 0.01). Their kidneys showed a significant increase in the relative organ weight (P < 0.01). Moreover, the MDA and GSH levels increased. Kidney tissue damage and renal cell apoptosis were observed, and the mRNA expression levels of genes related to the PERK signaling pathway significantly increased (P < 0.01). Compared with the Cd-treated group, the Cd + Que group exhibited a significant increase in body weight (P < 0.01) and significant decreases in the relative organ weight, MDA and GSH levels, and mRNA expression levels of genes related to the PERK signaling pathway (P < 0.01). Furthermore, kidney tissue damage and renal cell apoptosis were observed. CONCLUSION: Cd treatment resulted in rat weight loss, renal edema, and oxidative stress and caused renal tissue damage and cell apoptosis by activating the PERK signaling pathway. Que was able to restore the body weight and renal coefficient of rats. It also alleviated the oxidative stress and kidney tissue damage caused by Cd and the cell apoptosis caused by Cd through inhibiting the PERK signaling pathway. Thus, Que could be considered for the treatment of kidney diseases caused by Cd poisoning.

Quercetin alleviates cadmium-induced BRL-3A cell apoptosis by inhibiting oxidative stress and the PERK/IRE1α/ATF6 signaling pathway.

Cadmium (Cd) is a highly toxic environmental pollutant. The liver is an important metabolic organ in the body and is susceptible to Cd toxicity attacks. Quercetin (Que) is a flavonoid compound with pharmacological activities of scavenging free radicals and antioxidant activity. Previous studies have shown that Que can alleviate Cd caused hepatocyte apoptosis in rats, but the specific mechanism remains unclear. To explore the specific mechanism, we established a model of Cd toxicity and Que rescue in BRL-3A cells and used 4-phenylbutyrate (4-PBA), an endoplasmic reticulum stress (ERS) inhibitor, as positive control. Set up a control group, Cd treatment group, Cd and Que co treatment group, Que treatment group, Cd and 4-PBA co treatment group, and 4-PBA treatment group. Cell Counting Kit-8 (CCK-8) method was employed to measure cell viability. Fluorescence staining was applied to observe cell apoptosis. Flow cytometry was performed to detect reactive oxygen species levels. Real-time quantitative polymerase chain reaction (qRT-PCR) and Western blot method was adopted to detect the mRNA and protein expression levels of ERS and apoptosis-related genes. The results showed that compared with the control group, the Cd treated group showed a significant decrease in cell viability (P < 0.01), an increase in intracellular ROS levels, and apoptosis. The mRNA and protein expression levels of ERS and apoptosis related factors such as GRP78, IRE1α, XBP1, ATF6, Caspase-12, Caspase-3 and Bax in the cells were significantly increased (P < 0.01), while the mRNA and protein expression levels of Bcl-2 were significantly reduced (P < 0.01). Compared with the Cd treatment group, the Cd and Que co treatment group and the Cd and 4-PBA co treatment group showed a significant increase in cell viability (P < 0.01), a decrease in intracellular ROS levels, a decrease in cell apoptosis, and a significant decrease in the expression levels of ERS and apoptosis related factors mRNA and protein (P < 0.01), as well as a significant increase in Bcl-2 mRNA and protein expression (P < 0.01). We confirmed that Que could alleviate the apoptosis caused by Cd in BRL-3A cells, and the effects of Que were similar to those of ERS inhibitor.

Swainsonine inhibits autophagic degradation and causes cytotoxicity by reducing CTSD O-GlcNAcylation.

Swainsonine (SW) is the primary toxin in locoweed, a poisonous plant. SW can cause animal poisoning, affect the quality and safety of meat products and threaten human health, but the mechanism of its toxicity is little defined. Here, we identified 159 differentially expressed proteins, many of which are involved in autophagy and glycosylation modification processes, using proteomics sequencing analysis. O-linked-N-acetylglucosamylation (O-GlcNAcylation) is a glycosylation modification widely involved in various biological processes. Our results show that SW toxicity is related to O-GlcNAcylation. In addition, increased O-GlcNAcylation with the O-GlcNAcase (OGA) inhibitor TMG promoted autophagy, while decreased O-GlcNAcylation with the O-GlcNAc transferase (OGT) inhibitor OSMI inhibited autophagy. Further analysis by Immunoprecipitation (IP) showed that SW could change the O-GlcNAcylation of Cathepsin D (CTSD), reducing the expression of mature CTSD (m-CTSD). In summary, these findings suggest that SW inhibits the O-GlcNAcylation of CTSD, affecting its maturation and leading to the impairment of lysosome function. Consequently, it inhibits autophagy degradation, and causes cytotoxicity, providing a new theoretical basis for SW toxicological mechanism.

Effects of Glycyrrhiza polysaccharide on growth performance, appetite, and hypothalamic inflammation in broilers.

We analyzed the effects of Glycyrrhiza polysaccharide (GCP) on growth performance, appetite, and hypothalamic inflammation-related indexes in broilers. One-day-old male AA broilers were randomly divided into four groups: Control, L-GCP, M-GCP, and H-GCP (0, 300, 600, and 900 mg GCP/kg feed), with six repetition cages for each treatment and 12 broilers in each repeat for a period of 42 days. From day 1 to day 21, the addition of GCP to the diet significantly improved the ADFI and the ADG of broilers, and the mRNA levels of NPY and AgRP were significantly increased while POMC and CART were decreased in the hypothalamus of broilers; GCP also significantly decreased the mRNA levels of IL-1ß, IL-6, TNF-α, TLR-4, MyD88, and NF-κB, and increased the IL-4 and IL-10 in the hypothalamus from day 1 to day 42. The concentrations of appetite-related factors and inflammatory factors in serum were changed in the same fashion. Supplementation with 600 mg/kg GCP had the optimal effect in broilers, and GCP has the potential to be used as a feed additive in the poultry production industry.

In this work, we analyzed the effects of Glycyrrhiza polysaccharide on growth performance, appetite, and hypothalamic inflammation in broilers. In the past, antibiotics were added to poultry feed to prevent disease and improve growth performance; however, the extensive use of antibiotics can negatively affect livestock and poultry, and endanger the health of consumers. Glycyrrhiza polysaccharide has many biological activities. In order to explore the possibility of Glycyrrhiza polysaccharide as a substitute for antibiotics, we evaluated the effects of Glycyrrhiza polysaccharide added to the diet of broilers for 42 days. Our research confirmed that Glycyrrhiza polysaccharide supplementation increased food intake by regulating appetite-related factors in hypothalamus and serum, and also alleviated inflammation.

Protective effect of quercetin on cadmium-induced renal apoptosis through cyt-c/caspase-9/caspase-3 signaling pathway.

Cadmium (Cd), a heavy metal, has harmful effects on animal and human health, and it can also obviously induce cell apoptosis. Quercetin (Que) is a flavonoid compound with antioxidant and other biological activities. To investigate the protective effect of Que on Cd-induced renal apoptosis in rats. 24 male SD rats were randomly divided into four groups. They were treated as follows: control group was administered orally with normal saline (10 ml/kg); Cd group was injected with 2 mg/kg CdCl2 intraperitoneally; Cd + Que group was injected with 2 mg/kg CdCl2 and intragastric administration of Que (100 mg/kg); Que group was administered orally with Que (100 mg/kg). The experimental results showed that the body weight of Cd-exposed rats significantly decreased and the kidney coefficient increased. In addition, Cd significantly increased the contents of Blood Urea Nitrogen, Creatinine and Uric acid. Cd also increased the glutathione and malondialdehyde contents in renal tissues. The pathological section showed that Cd can cause pathological damages such as narrow lumen and renal interstitial congestion. Cd-induced apoptosis of kidney, which could activate the mRNA and protein expression levels of Cyt-c, Caspase-9 and Caspase-3 were significantly increased. Conversely, Que significantly reduces kidney damage caused by Cd. Kidney pathological damage was alleviated by Que. Que inhibited Cd-induced apoptosis and decreased Cyt-c, Caspase-9 and Caspase-3 proteins and mRNA expression levels. To sum up, Cd can induce kidney injury and apoptosis of renal cells, while Que can reduce Cd-induced kidney damage by reducing oxidative stress and inhibiting apoptosis. These results provide a theoretical basis for the clinical application of Que in the prevention and treatment of cadmium poisoning.

Alleviating effect of quercetin on cadmium-induced oxidative damage and apoptosis by activating the Nrf2-keap1 pathway in BRL-3A cells.

Cadmium (Cd) is a toxic heavy metal extensively used in industrial and agricultural production. Among the main mechanisms of Cd-induced liver damage is oxidative stress. Quercetin (QE) is a natural antioxidant. Herein, the protective effect of QE on Cd-induced hepatocyte injury was investigated. BRL-3A cells were treated with 12.5 µmol/L CdCl2 and/or 5 µmol/L QE for 24 h. The cells and medium supernatant were collected, and the ALT, AST, and LDH contents of the medium supernatant were detected. The activities or contents of SOD, CAT, GSH, and MDA in cells were determined. Intracellular ROS levels were examined by flow cytometry. Apoptosis rate and mitochondrial-membrane potential (ΔΨm) were detected by Hoechst 33,258 and JC-1 methods, respectively. The mRNA and protein expression levels of Nrf2, NQO1, Keap1, CytC, caspase-9, caspase-3, Bax, and Bcl-2 were determined by real-time PCR (RT-PCR) and Western blot methods. Results showed that Cd exposure injured BRL-3A cells, the activity of antioxidant enzymes decreased and the cell ROS level increased, whereas the ΔΨm decreased, and the expression of apoptotic genes increased. Cd inhibited the Nrf2-Keap1 pathway, decreased Nrf2 and NQO1, or increased Keap1 mRNA and protein expression. Through the combined action of Cd and QE, QE activated the Nrf2-Keap1 pathway. Consequently, antioxidant-enzyme activity decreased, cellular ROS level decreased, ΔΨm increased, Cd-induced BRL-3A cell damage was alleviated, and cell apoptosis was inhibited. After the combined action of QE and Cd, Nrf2 and NQO1 mRNA and protein expression increased, Keap1 mRNA and protein expression decreased. Therefore, QE exerted an antioxidant effect by activating the Nrf2-Keap1 pathway in BRL-3A cells.

Role of endoplasmic reticulum stress in cadmium-induced hepatocyte apoptosis and the protective effect of quercetin.

Cadmium (Cd) is one of the most toxic environmental pollutants. Quercetin (Que) is a kind of natural flavonoid with neuroprotective, antioxidant, and free-radical scavenging pharmacological activities. However, whether Que has the protective effect of on Cd-induced rat hepatocyte injury is unclear. This study aimed to determine the protective effect of Que on Cd-induced hepatotoxicity in vivo and in vitro. For in vivo, 36 4-week-old male SD rats were randomly divided into six groups and were treated with CdCl2 (2 mg/kg b.w.) and/or Que (50 or 100 mg/kg b.w.). Four weeks later, the rats were sacrificed and livers were collected. The levels of alanine aminotransferase, aspartate aminotransferase, glutathione, malondialdehyde, catalase, and superoxide dismutase were measured. Liver histopathological sections were made, and TUNEL method was performed to detect cell apoptosis. The mRNA and protein expression levels of endoplasmic reticulum stress (ERS) signaling pathway-related factors and apoptosis-related factors were detected. For in vitro, BRL-3A rat cells were treated with CdCl2 (12.5 µM) and/or Que (5 µM Que). The mRNA and protein expression levels of ERS signaling pathway-related factors and apoptosis-related factors were detected. Results showed that Cd led to liver injury, disorder of hepatocyte morphology and structure, decreased BRL-3A cells viabilities, increased oxidative damage. The mRNA and protein expression levels of ERS related factors GRP78, PERK, eIF2α, ATF4, CHOP, IRE1α, XBP1, and ATF6 increased. The mRNA and protein levels of apoptosis related factors Caspase12, Caspase3, and Bax increased, whereas Bcl2 decreased. It indicated that cadmium could activate PERK-eIF2α-ATF4-CHOP, IRE1α-XBP1, and ATF6-CHOP ERS-related signal pathways and lead to apoptosis. Moreover, Que can improve the vitality of hepatocytes, and effectively reduce hepatocytes damage, and reduce oxidative damage by Cd. As a result, the mRNA and protein expression levels of ERS related factors were reduced and hepatocyte apoptosis related factors decreased. Therefore, Que can be used as an effective component in daily diet to prevent Cd toxicity.

Estrogen deficiency aggravates fluorine ion-induced renal fibrosis via the TGF-ß1/Smad signaling pathway in rats.

To investigate the role and molecular mechanism of estrogen deficiency in fluorine ion (F-)-induced renal fibrosis, the models of F- exposure in ovary removed rats were established by drinking water with different doses of F- (0, 25, 50 and 100 mg/L) for 90 days. Results of H&E staining and BrdU labeled experiment showed that F- induced renal pathomorphological damage and inhibited cell proliferation. Further, Masson staining showed that F- induced renal glomerular and tubulointerstitial fibrosis. Meanwhile, renal fibrosis was confirmed by detecting the expression levels of collagen I, collagen III, collagen IV and fibronectin using immunofluorescence. In the state of estrogen deficiency, F--induced renal damage and fibrosis were aggravated. Moreover, the molecular mechanism of F--induced renal fibrosis was evaluated, and the results showed that F- induced TGF-ß1/Smad signaling pathway further dysregulation after ovariectomy, which manifested as the further up-regulated expression of TGF-ß1, Smad2, p-Smad2, Smad3 and p-Smad3, and further down-regulated of Smad7. Accompanied by renal damage and renal fibrosis, renal function was also disturbed, especially in ovariectomized rats. This study indicated that estrogen deficiency aggravated F--induced renal fibrosis via the TGF-ß1/Smad signaling pathway, leading to more serious renal dysfunction.

Protective effect of naringenin against cadmium-induced testicular toxicity in male SD rats.

This study aimed to investigate the effect of naringenin (Nar) on cadmium (Cd)-induced testicular toxicity. Twenty-four male Sprague-Dawley (SD) rats aged 5 weeks were used. Rats were administered with 0.9% NaCl (control group), CdCl2 (2 mg/kg b.w. intraperitoneally), Nar (50 mg/kg b.w, orally), and CdCl2 + Nar (2 mg/kg b.w intraperitoneally and 50 mg/kg b.w. orally, respectively) for 4 weeks. Results showed that body weight, relative testis weights, and sperm quality decreased in the Cd-treated group, and Cd accumulated in serum and testes. Pathological examination showed that Cd can cause testicular damage. Cd decreased the serum concentrations of gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone. It also decreased the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Moreover, exposure to Cd resulted in decreased content of reduced glutathione (GSH) and total antioxidant capacity (T-AOC) concentrations, as well as increased malondialdehyde (MDA) and hydrogen peroxide (H2O2) contents. Cd also provoked testis autophagy by upregulating the expression of the autophagy-related proteins P62 and LC3 II. However, the combined administration of Nar and Cd significantly attenuated the Cd-induced negative effects by increasing the body weight, relative testis weights, and sperm quality and by decreasing testicular damage. Simultaneous supplementation of Nar and Cd markedly restored the decreased levels of GnRH, FSH, LH, testosterone, GSH, and T-AOC and the activities of SOD, CAT, and GPx caused by Cd treatment. Nar further suppressed MDA and H2O2 production and protected the testes from Cd-induced autophagy by downregulating P62 and LC3 II expression. Therefore, Nar protected the testes from Cd-induced toxicity.

Protective effect of quercetin on rat testes against cadmium toxicity by alleviating oxidative stress and autophagy.

Cadmium (Cd), a highly toxic heavy metal, adversely affects human and animal health. Quercetin (Que) is a kind of flavonoid that can protect many tissues from the toxic effect of heavy metals. Although many studies have explored the adverse effects of cadmium on rats and other animals, the mechanism of Cd-induced testicular autophagy and the antagonistic effect of Que on cadmium remain unclear. In this study, Sprague-Dawley rats were treated with Cd, Que or Cd, and Que supplements to explore the mechanisms of Que-alleviated testis injury caused by Cd exposure. The rat body weight and relative testicular weight were measured. Morphological changes in testes and indices of oxidative stress were also examined. The expression levels of autophagy-related genes were detected as well. Results showed that Cd decreased the rat body weight and relative testicular weight and induced pathological changes in testes. Conversely, Que alleviated these changes. We also found that Cd increased the malondialdehyde content and decreased the contents of total superoxide dismutase, glutathione peroxidase, catalase, and glutathione. Moreover, the protein expression levels of P62 and LC3-II increased under Cd exposure conditions. Conversely, Que obviously alleviated these toxic activities induced by Cd. Overall, this study showed that Cd accumulated in rat testes, leading to oxidative stress and autophagy. Que can reduce cadmium toxicity by reducing oxidative stress and inhibiting autophagy. The specific mechanism of Que antagonizing Cd toxicity can provide new insights into countering cadmium toxicity.

Effect of oleic acid on induction of steatosis and cytotoxicity in BRL 3A cells.

Recent studies have shown that monounsaturated oleic acid induces steatosis in cultured hepatocyte steatosis in the form of nonalcoholic fatty liver disease models in vitro. However, the underlying mechanism of steatosis development is not completely understood. Therefore, we investigated the molecular mechanism of steatosis and the role of mitogen-activated protein kinase (MAPK)/toll-like receptor 4-related protein (TLR4) expression in this study. Rat hepatocyte cells were subjected to oleic acid in different concentrations (1.2-2.4 mM) for 24 hours. The cell morphological injury index and the changes in the MAPK/TLR4 signaling pathway-related proteins were evaluated. We found that the microstructure of the cells in the oleic acid treatment group was damaged, and higher phosphorylation levels of the MAPK pathway-related proteins were detected than those in the control group. In addition, the protein expression of TLR4, sterol regulatory element-binding protein-1, and fatty acid synthase were increased in the oleic acid treatment group. Our findings demonstrate that oleic acid causes toxic damage to rat hepatocyte cells, and the MAPK/TLR4 signaling pathway plays a significant role in lipid storage.

A patent review of the ubiquitin ligase system: 2015-2018.

INTRODUCTION: Ubiquitin-proteasome system (UPS) has been validated as a novel anticancer drug target in the past 20 years. The UPS contains two distinct steps: ubiquitination of a substrate protein by ubiquitin activating enzyme (E1), ubiquitin conjugating enzyme (E2), and ubiquitin ligase (E3), and substrate degradation by the 26S proteasome complex. The E3 enzyme is the central player in the ubiquitination step and has a wide range of specific substrates in cancer cells, offering great opportunities for discovery and development of selective drugs. Areas covered: This review summarizes the recent advances in small molecule inhibitors of E1s, E2s, and E3s, with a focus on the latest patents (from 2015 to 2018) of E3 inhibitors and modulators. Expert opinion: One strategy to overcome limitations of current 20S proteasome inhibitors is to discover inhibitors of the upstream key components of the UPS, such as E3 enzymes. E3s play important roles in cancer development and determine the specificity of substrate ubiquitination, offering novel target opportunities. E3 modulators could be developed by rational design, natural compound or library screening, old drug repurposes, and application of other novel technologies. Further understanding of mechanisms of E3-substrate interaction will be essential for discovering and developing next-generation E3 inhibitors as effective anticancer drugs.

PI3K/AKT signaling pathway involvement in fluoride-induced apoptosis in C2C12 cells.

To investigate the mechanisms of fluoride-induced apoptosis, a fluoride-induced C2C12 skeletal muscle cell (C2C12 cell) model was established in this study, and the viability of the C2C12 cells was measured using an MTT assay. Cell morphological changes were observed via haematoxylin and eosin staining and transmission electron microscopy. Apoptosis was monitored through Hoechst staining. The mRNA and protein expression of PI3K, PDK1, AKT1, BAD, Bcl-2, Bax and caspase-9 were detected through real-time PCR and western blotting, respectively. The results showed that the survival rates of C2C12 cells decreased gradually with an increasing fluoride doses. The C2C12 cell structure was seriously damaged by fluoride, presenting with pyknosis, mitochondrial ridge disruption and swollen endoplasmic reticulum. Furthermore, the expression of mRNA in PI3K, BAD, Bcl-2, Bax and caspase-9 were significantly increased in the fluoride group (P < 0.01), while the expression of PDK1 was markedly decreased (P < 0.01). The expression of protein in BAD, Bcl-2 and Bax were significantly increased in the fluoride group (P < 0.01), while the expression of PDK1 and P-AKT1 was markedly decreased (P < 0.01). In conclusion, fluoride-induced apoptosis in C2C12 cells is related to the PI3K/AKT signaling pathway.

N-acetylcysteine protects against cadmium-induced oxidative stress in rat hepatocytes.

Cadmium (Cd) is a well-known hepatotoxic environmental pollutant. We used rat hepatocytes as a model to study oxidative damage induced by Cd, effects on the antioxidant systems, and the role of N-acetylcysteine (NAC) in protecting cells against Cd toxicity. Hepatocytes were incubated for 12 and 24 h with Cd (2.5, 5, 10 µM). Results showed that Cd can induce cytotoxicity: 10 µM resulted in 36.2% mortality after 12 h and 47.8% after 24 h. Lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase activities increased. Additionally, reactive oxygen species (ROS) generation increased in Cd-treated hepatocytes along with malondialdehyde levels. Glutathione concentrations significantly decreased after treatment with Cd for 12 h but increased after 24 h of Cd exposure. In contrast, glutathione peroxidase activity significantly increased after treatment with Cd for 12 h but decreased after 24 h. superoxide dismutase and catalase activities increased at 12 h and 24 h. glutathione S-transferase and glutathione reductase activities decreased, but not significantly. Rat hepatocytes incubated with NAC and Cd simultaneously had significantly increased viability and decreased Cd-induced ROS generation. Our results suggested that Cd induces ROS generation that leads to oxidative stress. Moreover, NAC protects rat hepatocytes from cytotoxicity associated with Cd.

Oxidative stress and Ca(2+) signals involved on cadmium-induced apoptosis in rat hepatocyte.

Cadmium (Cd) is an important industrial and environmental pollutant. In animals, the liver is the major target organ of Cd toxicity. In this study, rat hepatocytes were treated with 2.5∼10 µM Cd for various durations. Studies on nuclear morphology, chromatin condensation, and apoptotic cells demonstrate that Cd concentrations ranging within 2.5∼10 µM induced apoptosis. The early-stage marker of apoptosis, i.e., decreased mitochondrial membrane potential, was observed as early as 1.5 h at 5 µM Cd. Significant (P < 0.01) reactive oxygen species (ROS) production at 5 µM Cd and 0.75 h occurred prior to the decrease of the mitochondrial membrane potential, suggesting the involvement of ROS in mitochondrial membrane damage. Glutathione (GSH) level significantly decreased after cell treatment with 5 and 10 µM Cd after 12 h (P < 0.01). Meanwhile, the intracellular free Ca(2+) concentration ([Ca(2+)] i ) of Cd-exposed cells significantly increased (P < 0.01) at 1.5 h, and pretreatment with the calcium chelator Bapta-AM partially blocked Cd-induced apoptosis. This finding indicated that the elevation of [Ca(2+)] i may play an important role in apoptosis. Overall, these results showed that oxidative stress and Ca(2+) signaling were critical mediators of the Cd-induced apoptosis of rat hepatocytes.

Antioxidative effects of hesperetin against lead acetate-induced oxidative stress in rats.

OBJECTIVES: Oxidative stress with subsequent lipid peroxidation (LP) has been suggested as a mechanism for lead-induced toxicity. The current study was carried out to evaluate antioxidant activity of hesperetin against lead acetate-induced oxidative stress. MATERIALS AND METHODS: The male rats were treated with hesperetin in combination with lead acetate (500 mg/L). RESULTS: The results indicated that hesperetin alone did not induce any significant changes in the biochemistry of serum, liver, and kidney tissues. On the other hand, lead-induced oxidative stress as indicated by significant changes in serum biochemical parameters, including increased lipid peroxide and decreased reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) levels in liver and kidney tissues. Hesperetin succeeded in improving these biochemical parameters towards the normal values of control. CONCLUSIONS: It suggests that hesperetin shows antioxidant activity and plays a protective role against lead-induced oxidative damage in liver and kidney of rats.

Protective effect of naringenin against lead-induced oxidative stress in rats.

Oxidative stress is thought to be involved in lead-induced toxicity. The aim of this study was to investigate the possible protective role of naringenin on lead-induced oxidative stress in the liver and kidney of rats. In the present investigation, lead acetate (500 mg Pb/L) was administered orally for 8 weeks to induce hepatotoxicity and nephrotoxicity. The levels of hepatic and renal markers such as alanine aminotransferase, aspartate aminotransferase, urea, uric acid, and creatinine were significantly (P < 0.05) increased following lead acetate administration. Lead-induced oxidative stress in liver and kidney tissue was indicated by a significant (P < 0.05) increase in the level of maleic dialdehyde and decreased levels of reduced glutathione, superoxide dismutase, catalase, and glutathione peroxidase. Naringenin markedly attenuated lead-induced biochemical alterations in serum, liver, and kidney tissues (P < 0.05). The present study suggests that naringenin shows antioxidant activity and plays a protective role against lead-induced oxidative damage in the liver and kidney of rats.