Houjuan Xing

Histopathological changes and antioxidant response in brain and kidney of common carp exposed to atrazine and chlorpyrifos

We investigated oxidative stress response and histopathological changes in the brain and kidney of the common carp after a 40-d exposure to CPF and ATR, alone or in combination, and a 20-d recovery. Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities and malondialdehyde (MDA) content were measured using standard assays. Our results indicated that exposure to ATR, CPF or a combination of the two for 40 d induced significant changes in antioxidant enzyme (SOD, CAT and GSH-Px) activities and MDA content in the brain and kidney of the common carp. Pathological changes included tissue damage that was more severe with increased of exposure dose. To our knowledge, this is the first report to study oxidative stress and histopathological effects caused by subchronic exposure to ATR, CPF and ATR/CPF combination on common carp. The information presented in this study may be helpful to understanding the mechanisms of ATR-, CPF- and ATR/CPF combination-induced oxidative stress in fish.

Effects of atrazine and chlorpyrifos on activity and transcription of glutathione S-transferase in common carp (Cyprinus carpio L.).

Glutathione S-transferase isoenzymes (GSTs) play a critical role in detoxification pathways. Here we report the tissue distribution of four antioxidant GSTs gene in common carp, and their expression profiles. We also investigated the GSTs activity in different tissues after exposure to the agricultural chemicals atrazine (ATR), chlorpyrifos (CPF), and their mixture. Relative changes in the mRNA abundance of the GST isoforms were examined by real time PCR in liver, brain, kidney and gill of common carp. After exposure and recovery, we observed a statistically significant decrease in the GSTs activity in animals exposed to high concentrations of ATR (428 μg/L), CPF (116 μg/L), and their mixture (113 μg/L). At basal levels of tissue expression, four GSTs transcript were detected in liver, brain, kidney, and gill. High expression levels were found in all examined tissues. Transcription of some GST isoforms, GST kappa (GSTK), GST theta (GSTT) and GST rho (GSTR), decreased after exposure to CPF and ATR for the entire experimental period in both the kidney and gill. However, increased transcription of GST mu (GSTM) was observed in the kidney or gill 20 d after exposure to ATR or CPF, respectively. Transcription of both GSTT and GSTR was inhibited for the entire experimental period in the brain, kidney and gill of animals exposed to the ATR/CPF mixture, but transcription of GSTM was induced in the liver after 40 d of exposure. In summary, changes in the GSTs activity and their transcription varied within each organ and among organs of common carp after exposure to ATR, CPF, and their mixture.

Effects of atrazine and chlorpyrifos on the mRNA levels of IL-1 and IFN-γ2b in immune organs of common carp.

Atrazine (ATR) and chlorpyrifos (CPF) are widely used in agriculture has resulted in a series of toxicological and environmental problems. The aim of this study was to investigate the effects of ATR, CPF and their mixture on the mRNA levels of interleukin-1β (IL-1β), interleukin receptor I (IL-1RI) and interferon gamma (IFN-γ2b) in both spleen and head kidney of Common carp. In this study, juvenile common carp were exposed to ATR (at concentrations of 4.28, 42.8 and 428 μg/L), CPF (at concentrations of 1.16, 11.6 and 116 μg/L), and their mixture (at concentrations of 1.16, 11.6 and 116 μg/L). The mRNA levels of IL-1β, IL-1R1 and IFN-γ2b in spleen and head kidney were detected by using RT-PCR. Our results indicated that IL-1β, IL-1R1 expression significantly increased after exposure in high concentration ATR, CPF and their mixture, but IFN-γ2b mRNA shown different expression trends. Our results suggested that ATR, CPF and their mixture probably induced damages on spleen and head kidney may be association with increasing IL-1β, IL-1R1 mRNA synthesis. After 20-day recovery test, IL-1β, IL-1R1 and IFN-γ2b mRNA expression remain at high level in majority of the treated groups, we concluded that the restoration of tissue and immune system damage probably needs longer time.

Effects of atrazine and chlorpyrifos on acetylcholinesterase and Carboxylesterase in brain and muscle of common carp

The aim of this study was to investigate the effects of chlorpyrifos (CPF), atrazine (ATR) and the mixture of them on acetylcholinesterase (AChE) and carboxylesterase (CbE) in brain and muscle of common carp, respectively. 220 carps were averagely divided into 11 groups according to the different treatments and concentration, including the exposure and recovery experiments. The activities of AChE and CbE of the brain and muscle were determined at the end of the exposure and the recovery. The results showed that in the control group, the specific enzymatic activities in the brain were higher than that in the muscle. The activities of AChE and CbE in the exposure groups were significantly lower than that in the control group except for the CbE activity in the ATR low-dose group. There was a negative dose-response relationship between the activities of AChE and CbE and the pesticides concentration. The activities of AChE and CbE in the recovery groups were significantly higher than that in the exposure group except for the CbE activity in the ATR low-dose group, AChE activity in the high-dose group of the mixture of ATR and CPF, and AChE activity of the brain in the CPF high-dose group. The results suggested that: (1) brain AChE may be considered as a very sensitive and early biomarker of exposure to CPF, ATR, or the mixture of ATR and CPF, (2) brain CbE may be used as a secondary biomarker for evaluating the exposure to CPF, ATR, or the mixture of ATR and CPF and (3) the change of the AChE and CbE activities caused by the mixture of ATR and CPF was more sensitive than that caused by the ATR or CPF alone.

Effects of atrazine and chlorpyrifos on cytochrome P450 in common carp liver.

Atrazine (ATR) and chlorpyrifos (CPF), widely used in agriculture, have resulted in a series of toxicological and environmental problems. We investigated the activities of the biotransformation enzymes ethoxyresorufin-O-deethylase (EROD) and pentoxyresorufin-O-deethylase (PROD), total cytochrome P450 (CYP), CYP1A mRNA level and level of tissue ATR, CPF, and their metabolites in the liver of common carp (Cyprinus carpio L.) after a 40-d exposure to CPF and ATR, alone or in combination, and a 20-d recovery. In the present study, juvenile common carp was exposed to ATR (at concentrations of 4.28, 42.8 and 428 μg L(-1)), CPF (1.16, 11.6 and 116 μg L(-1)), and ATR/CPF mixture (at concentrations of 1.13, 11.3 and 113 μg L(-1)). A general increasing trend for the activity of the biotransformation enzymes (EROD and PROD), CYP and CYP1A mRNA level was observed in the liver of common carp exposed to ATR, CPF and the ATR/CPF mixture. In addition, ATR, CPF, and their metabolites demonstrated a high accumulation in the liver. These results demonstrated that the CYP system in fish could be used as a biomarkers in evaluating the impact of ATR and CPF exposure on the common carp.

Effect of atrazine and chlorpyrifos exposure on cytochrome P450 contents and enzyme activities in common carp gills

Chlorpyrifos (CPF) and atrazine (ATR) are the most widely used organophosphate insecticides and triazine herbicides, respectively, worldwide. This study aimed at investigating the effects of ATR, CPF and mixture on common carp gills following 40-d exposure and 40-d recovery experiments. Cytochrome P450 content, activities of aminopyrine N-demethylase (APND) and erythromycin N-demethylase (ERND) and the mRNA levels of the CYP1 family (CYP1A, CYP1B, and CYP1C) were determined. In total, 220 common carps were divided into eleven groups, and each group was treated with a specific concentration of ATR (4.28, 42.8 and 428 μg/L), CPF (1.16, 11.6 and 116 μg/L) or ATR-CPF mixture (1.13, 11.3 and 113 μg/L). The results showed that P450 content and activities of APND and ERND in fish exposed to ATR and mixture were significantly higher than those in the control group. After the 40-d recovery treatment (i.e., depuration), the P450 content and the activities of APND and ERND in fish decreased to the background levels. A similar tendency was also found in the mRNA levels of the CYP1 family (CYP1A, CYP1B, and CYP1C) in common carp gills. The CPF-treated fish showed no significant difference from the control groups, except for a significant CYP1C induction. These results indicated that CYP enzyme levels are induced by ATR but were only slightly affected by CPF in common carp gills. In addition, the ATR and CPF exposure showed an antagonistic effect on P450 enzymes in common carp gills.

Selenium regulates gene expression of selenoprotein W in chicken gastrointestinal tract.

Selenoprotein W (SelW) is an existing form of selenium (Se). Se influences the levels of SelW in mammals. However, little is known about the pattern of SelW expression in the gastrointestinal tract tissue of bird. The present paper describes the effects of different dietary levels of Se on the SelW mRNA expression in the gastrointestinal tract tissue of chicken. The expression levels of SelW mRNA and the Se contents in the gastrointestinal tract tissues (glandular stomach, gizzard, duodenum, small intestine, and rectum) were determined on days 15, 25, 35, 45, and 55, respectively. The results showed that the Se contents and the SelW mRNA expression were significantly higher (p < 0.05) in the high-Se group, and the Se contents and SelW mRNA expression in the low-Se group were significantly lower (p < 0.05) than in the controls. The Se contents were the highest in the duodenum and the lowest in the rectum, while the SelW mRNA expression was the highest in the gizzard and the lowest in the rectum. In addition, the SelW mRNA levels in the gastrointestinal tract tissue were found to increase in a time-dependent manner with increasing feeding time. Furthermore, the expression of the SelW mRNA in the gastrointestinal tract tissues of chickens was found to correlate with the dietary Se concentrations, but not with the tissue Se contents.

Neurotoxicity induced by arsenic in Gallus Gallus: Regulation of oxidative stress and heat shock protein response

Arsenic, a naturally occurring heavy metal pollutant, is one of the functioning risk factors for neurological toxicity in humans. However, little is known about the effects of arsenic on the nervous system of Gallus Gallus. To investigate whether arsenic induce neurotoxicity and influence the oxidative stress and heat shock proteins (Hsps) response in chickens, seventy-two 1-day-old male Hy-line chickens were treated with different doses of arsenic trioxide (As2O3). The histological changes, antioxidant enzyme activity, and the expressions of Hsps were detected. Results showed slightly histology changes were obvious in the brain tissues exposure to arsenic. The activities of Glutathione peroxidase (GSH-Px) and catalase (CAT) were decreased compared to the control, whereas the malondialdehyde (MDA) content was increased gradually along with increase in diet-arsenic. The mRNA levels of Hsps and protein expressions of Hsp60 and Hsp70 were up-regulated. These results suggested that sub-chronic exposure to arsenic induced neurotoxicity in chickens. Arsenic exposure disturbed the balance of oxidants and antioxidants. Increased heat shock response tried to protect chicken brain tissues from tissues damage caused by oxidative stress. The mechanisms of neurotoxicity induced by arsenic include oxidative stress and heat shock protein response in chicken brain tissues.

Alterations in mRNA expression of acetylcholinesterase in brain and muscle of common carp exposed to atrazine and chlorpyrifos.

The uses of pesticides and herbicides have become an integral part of modern agricultural systems. The intensive use of pesticides chlorpyrifos (CPF) and herbicides atrazine (ATR) has resulted in serious environmental problems. Herein, we have developed real-time quantitative polymerase chain reaction assays for common carp (Cyprinus carpio L.) mRNA. The levels of AChE mRNA were evaluated in brain and muscle collected from common carp by treatment of ATR, CPF, and their mixture. The decreased transcription of AChE was detected in both tissues at different doses of the toxicants in the end of exposure tests, and the changes were improved in the end of recovery tests in varying degrees. It is suggested that transcription inhibition of AChE might be significant in long-playing single or associated exposure of ATR and CPF in common carp. Alteration in transcription of AChE caused by ATR, CPF, and their mixture could reveal the toxic mechanisms related to cholinergic signaling.

Accumulation, histopathological effects and response of biochemical markers in the spleens and head kidneys of common carp exposed to atrazine and chlorpyrifos

This study assessed the impacts of atrazine (ATR), chlorpyrifos (CPF) and combined ATR/CPF exposure on the immune organs of common carp (Cyprinus carpio L.). The carp were sampled after a 40-d exposure to CPF and ATR, individually or in combination, followed by a 20-d recovery to measure the acid phosphatase (ACP), alkaline phosphatase (ALP), Na(+)/K(+)-ATPase, superoxide dismutase (SOD) and malondialdehyde (MDA) content. In addition, we also investigated histopathological changes and pesticide residues in the spleen and head kidney. The results revealed that the responses of SOD, MDA, ALP, ACP, and Na(+)/K(+)-ATPase to ATR, CPF and ATR/CPF combination exposure presented in a dose-dependent manner. The ACP activity and MDA content were significantly induced with increasing concentrations of ATR, CPF and combined ATR/CPF. However, the enzyme activities (SOD, ALP, and Na(+)/K(+)-ATPase) were reduced under exposure to increasing concentrations of these compounds. The accumulated amounts of ATR, CPF, and their metabolites in the spleens and head kidneys tissues exhibited dose-dependency. Pathological changes included tissue damage that was more severe with increasing exposure doses. SOD activity negatively correlated with MDA accumulation. The biochemical parameters exhibited sensitivity to ATR and CPF, suggesting that they may act as potential biomarkers for assessing the environmental ATR and CPF risk for carp.