Action of cadmium on the elemental composition and cellular morphology of the hepatopancreas, kidneys and gonads of the mussel Mytilus edulis and scallop Mizuhopecten yessoensis

Studies have been made on the content and distribution of Cd, K, Mg, Ca, S and P in organs and cells of mussels and scallops before and after immersion in water containing cadmium chloride. In normal molluscs, the lowest content of Cd was found in the gonads; cadmium content of the hepatopancreas and kidney in the scallop is correspondingly 20 and 40 times higher than in the mussel. After immersion in water with cadmium (250 micrograms/l in summer experiments and 500 micrograms/l in spring ones), cadmium content of the hepatopancreas and kidney of the scallop was found to be also higher than that in the mussel, although the difference is less significant, being dependent on the season of year. The highest accumulation of cadmium (9.760 +/- 790 micrograms/g dry weight) was observed in the scallop kidney in summer period. After immersion in cadmium-containing water, the content of sulphur in the kidney and hepatopancreas increases, positive correlation being observed between the distribution of Cd and S. Exposure to cadmium results in the increase of Ca and Mg content in the gonads of scallops, as well as in the increase in Ca content of the gonads of mussels. Accumulation of cadmium in the gonads is rather small, maximum density of the material being observed histochemically in the gonadal wall. Morphological changes in the gonadal cells of mussels in summer period may be associated with the increase in cellular calcium.     

中华绒螯蟹对Pb和Cd的富集与释放特性

应用生物富集双箱动力学模型模拟了中华绒螯蟹(Eriocheir sinensis)分别在Pb浓度为0.25、0.50、0.75mg/L,Cd浓度为0.025、0.050、0.075mg/L的单一水环境中暴露时,蟹鳃、肝胰腺、肌肉和血淋巴对Pb和Cd的生物富集与释放实验,并通过非线性拟合得到中华绒螯蟹对Pb和Cd的富集速率常数k1、排出速率常数k2、生物富集系数BCF、生物半衰期B1/2、富集平衡时生物体内Pb和Cd含量CAmax等动力学参数。结果表明:(1)中华绒螯蟹对Pb和Cd具有明显的富集,蟹鳃、肝胰腺和肌肉中Pb和Cd的含量与富集时间和水环境中Pb和Cd暴露浓度表现出了很好的正相关,血淋巴在富集阶段没有明显的规律。理论平衡状态下鳃、肝胰腺和肌肉中Pb和Cd含量CAmax随着暴露浓度的增大而增大,且成正相关。(2)Pb和Cd在中华绒螯蟹组织器官中的富集具有选择性,开始实验前,Pb在中华绒螯蟹体内的的分布规律为:肝胰腺>鳃>肌肉>血淋巴;Cd的分布规律为:鳃>肝胰腺>血淋巴>肌肉。在实验浓度的Pb和Cd水环境中暴露16d后,Pb的分布规律为:鳃>肝胰腺>肌肉>血淋巴;Cd的分布规律为:肝胰腺>鳃>肌肉>血淋巴。(3)中华绒螯蟹对Pb和Cd的生物富集和释放都较缓慢。经过16d的生物富集,各组织器官中Pb和Cd的含量均未达到稳态平衡。Pb和Cd在组织器官中的生物富集系数(BCF)范围分别为5-51和6-3148,中华绒螯蟹对Cd的富集能力明显高于Pb(P1/2)范围分别为4-9d和8-57d,中华绒螯蟹对Cd的排出能力明显低于Pb。       

Cadmium accumulation in organs of the scallop Mizuhopecten yessoensis--II. Subcellular distribution of metals and metal-binding proteins

Cd accumulation in the hepatopancreas and gills of the scallop resulted in an increase of metal concentration in the cytoplasm, while in control animals the general amount of Cd in the hepatopancreas was concentrated in the microsomes and cytoplasm. Cd appears to be equally distributed among high molecular weight proteins and metallothioneins in control animals. It was shown that during the experiment the metal was bound mainly to high molecular weight proteins. After 30 days of exposure of scallops to flowing water Cd was redistributed to metallothionein (MT)-like proteins. Cd concentration in the lipids of the hepatopancreas of control and experimental scallops was equal.     

镉对克氏原螯虾肝胰腺抗氧化系统的影响

采用毒性试验方法,研究了不同浓度Cd2+(1.72、3.44、6.89、13.77和27.55mg·L-1)对克氏原螯虾肝胰腺抗氧化酶(SOD、CAT、GSH-PX)和抗氧化物质(GSH、Vc)的影响.结果表明:超氧化物歧化酶(SOD)活性受低浓度Cd2+诱导和高浓度Cd2+抑制,且受抑制程度与Cd2+浓度呈正相关.过氧化氢酶(CAT)活性总体表现为先激活后下降,且在第3天达最大值,CAT活性对低浓度Cd2+(≤6.89 mg·L-1)暴露敏感,而高浓度Cd2+对其影响较小.谷胱甘肽过氧化物酶(GSH-PX)活性对Cd2+浓度敏感,当Cd2+≤6.89 mg · L-1时,GSH-PX活性先升高后下降,更高浓度下GSH-PX活性在暴露后第1天即表现出抑制作用.还原型谷胱甘肽(GSH)含量在Cd2+≤6.89 mg·L-1时始终被诱导,且均在第1天达最大值,而高浓度Cd2+(≥13.77 mg·L-1)对GSH含量影响不明显.维生素C(Vc)对Cd2+胁迫敏感,各处理组Vc含量在第1天均显著下降,且下降程度与Cd2+浓度呈正相关,之后具有一定的合成恢复能力.抗氧化酶和非酶抗氧化物质在抵御Cd2+胁迫反应中共同发挥作用,且大多表现出明显的时间和剂量效应性.GSH-PX和Vc可以作为Cd2+污染的潜在生物指示物.     

重金属离子对凡纳滨对虾肝胰脏、鳃丝和血液SOD活力的影响

研究了3种重金属离子(Cu²⁺、Zn²⁺、Cd²⁺)在96 h内对凡纳滨对虾(Litopenaeus vannamei)对肝胰脏、鳃丝和血液超氧化物歧化酶(SOD)活力的影响.结果表明,凡纳滨对虾SOD活力在3种重金属离子作用下随取样时间变化显著(P＜0.0),Cu²⁺在实验浓度范围内(0.1～1 mg·L^-1),肝胰脏、鳃丝和血液的SOD活力随时间延长呈一峰值变化,Zn²⁺在10 mg·L^-1时对肝胰脏表现为显著抑制作用,Cd²⁺在0. mg·L^-1时对肝胰脏和鳃丝起显著抑制作用,0.2 mg·L^-1对鳃丝SOD活力无显著变化(P＞0.0),其他浓度Zn²⁺(＜10 mg·L^-1)、Cd²⁺(＜0.2 mg·L^-1)对各组织器官SOD活力的影响随时间延长均呈现先升高后下降的趋势.3种重金属离子对凡纳滨对虾肝胰脏、鳃丝、血液SOD活力的影响呈现明显的剂量-时间效应关系.其SOD活力大小顺序为肝胰脏＞鳃丝＞血液,3种重金属离子对凡纳滨对虾伤害大小顺序为Cd²⁺＞Cu²⁺＞Zn²⁺.     

Effects of Cadmium on Lipid Storage and Metabolism in the Freshwater Crab Sinopotamon henanense

Since environmental effects of molecular traits are often questioned we analyze here the molecular effects of cadmium (Cd) on lipid pathways and their effects on tissues development. Lipids are an important energy source for the developing embryo, and accumulate in the ovary and hepatopancreas of decapod crustaceans. The extend of Cd affecting lipid storage and metabolism, is studied here with the freshwater crabs Sinopotamon henanense. Crabs were exposed to water-born Cd at 1.45, 2.9, 5.8 mg/l for 10, 15, and 20 days. With significantly increased Cd accumulation in exposed crabs, lipid content in hepatopancreas and ovary showed a time-dependent and concentration-dependent reduction, being at least one of the reasons for a lower ovarian index (OI) and hepatopancreatic index (HI). After 10-day exposure increased triglyceride (TG) level in hemolymph and up-regulation of pancreatic lipase (PL) activity in the hepatopancreas suggested an increased nutritional lipid uptake. However, two processes led to lower lipid levels upon Cd exposure: an increased utilization of lipids and a down-regulated lipoprotein lipase (LPL) led to insufficient lipid transport. 10-day Cd exposure also triggered the production of β-nicotinamide adenine dinucleotide 2''-phosphate reduced tetrasodium salt hydrate (NADPH), as well as to the synthesis of adenosine triphosphate (ATP) and fatty acids. With increasing exposure time, the crabs at 15 and 20-day exposure contained less lipid and TG, suggesting that more energy was consumed during the exposure time. Meanwhile, the level of NADPH, ATP and the activity of PL, LPL, fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC) activity was down-regulated suggesting an impairment of the crab metabolism by Cd in addition to causing a lower lipid level.     

Molecular characterization and expression of metallothionein from freshwater pearl mussel,Hyriopsis schlegelii

Two metallothionein genes (HsMT1 and HsMT2) were first identified and described from Hyriopsis schlegelii. The open reading frame of HsMT1 and HsMT2 were 216 and 222 bp, encoding a protein of 71 and 73 amino acid residues. The deduced amino acid sequences showed they contained parts of typical MT characteristics, apart from HsMT2 lacked Cys–Cys motifs. The phylogenetic tree showed HsMT1 shared a high similarity with that of other molluscs, but HsMT2 was split into a distinct group separated from known molluscan MTs. HsMT1 exhibited constitutive expression in all examined tissues and the highest expression occurred in hepatopancreas, however, nearly all HsMT2 was just detected in gonad. After Cd exposure, their mRNA levels presented similar expression patterns. The transgenic bacteria of HsMT1 showed higher tolerance than HsMT2 in Cd environment. It was implied that HsMT1 and HsMT2 were involved in metal response but HsMT2 might have other physiological functions.     

Biochemical changes associated with cadmium and copper stress in germinating pea seeds (Pisum sativum L.)

Seeds of pea (Pisum sativum L.) were germinated for four days over two sheets of filter paper moistened with H2O (control) and 5 mM Cd(NO3)2 or CuSO4 (treated). The relationship between heavy-metal stress and breakdown of storage compounds was studied. Germination rate and growth of radicle decreased, while the water content in stressed seeds remained around the control values. Cotyledons changed their biochemical constituents: disorders in the contents of micronutrients (Fe, Mn, Zn), free amino acids and soluble sugars were found. Decline of alpha-amylase activity as well as acid phosphatase were also observed, whereas beta-amylase and alkaline phosphatase ones were not modified by heavy-metal treatments. These results suggest that the inhibition of seed germinations after exposure to cadmium or copper is not the consequence of starvation in water uptake by seed tissues, but may be due to a failure in the reserve mobilization process from cotyledons.     

Effects of heavy metals Cd2+, Pb2+ and Zn2+ on DNA damage of loach Misgurnus anguillicaudatus

The effects of heavy metals Cd2+, Pb2+ and Zn2+ at 0.05, 0.5 and 5.0 mg/L level and their interactions at 0.5 mg/L level on DNA damage in hepatopancreas of loach Misgurnus anguillicaudatus for 1-35 days exposure were examined by single cell gel electrophoresis (SCGE). For each test group, 20 loaches with similar body size (5.17-7.99g; 11.79-13.21 cm) were selected and kept in aquaria with dechlori-nated water at (22±1)℃ and fed a commercial diet every 48 h. According to the percentage of damaged DNA with tail and its TL/D (tail length to diameter of nucleus) value, the relationship between DNA damage degree and heavy metal dose and exposure time was determined. Results showed that the percentage of damaged DNA and the TL/D value were increased with the prolonged exposure time. The highest percentage (84.85%) of damaged DNA was shown in 5.0 mg/L Zn2+ group after 28 days exposure and the biggest TL/D value (2.50) in all treated groups after 35 days exposure. During the first treated week, the damnification of DNA was mainly recognized as the first level, after that time, the third damaged level was mostly observed and the percentage of damaged DNA was beyond 80%. The joint toxic effects among Cd2+, Pb2+ or Zn2+ revealed much complexity, but it generally displayed that the presence of Cd2+ could enhance the genotoxicity of Pb2+ or Zn2+. In conclusion, the results suggested that there was a significant time-and dose-depended relationship between the heavy metal and DNA damage in hepatopancreas of loach, and SCGE could represent a useful means to evaluate the genotoxicity of environmental contamination on aquatic organisms.     

Metallothionein, antioxidant enzymes and DNA strand breaks as biomarkers of Cd exposure in a marine crab, Charybdis japonica

Cadmium (Cd) is one of the most toxic heavy metals that are widespread in inshore sediments of China, and can induce the production of toxic hydroxyl radicals that cause cell damage. The present study investigated the effect of two Cd concentrations (the final Cd concentration of 0.025 and 0.05 mg/L, prepared with CdCl2 x 2.5H2O) on metallothioneins (MT), antioxidant enzyme activities (superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx)) and DNA integrity (DNA strand breaks) for up to 15 days in the gills and hepatopancreas of the portunid crab Charybdis japonica. The result indicated that MT was significantly induced after 3 days, with a dose-response relation between MT contents and Cd concentrations in two tissues and has a time-response relation in hepatopancreas during the experimental period; SOD, CAT and GPx activities could be stimulated after 0.5 day, all attained peak value and then reduced during the experimental period, but were not inhibited at day 15, except SOD and CAT in gills. Gill was more sensitive to Cd than hepatopancreas, and the hepatopancreas was the main detoxification tissue to deal with oxyradicals. DNA strand breaks were induced after 0.5 day, and there was a positive dose-response relation between DNA damage levels and Cd concentrations in gills, rather than hepatopancreas due to higher DNA repair activities. These results suggest the mechanisms of Cd toxicity and detoxification strategies in both tissues of C. japonica; in addition, the use of the biomarkers as indices for biomonitoring potential toxic effect of Cd in situ is discussed.     

Acid and alkaline phosphatase activities in lithium treated testis, prostate and seminal vesicles of adult albino rats: evidence of duration and dose dependent response

Changes in the activities of acid and alkaline phosphatase were observed in the testis, prostate and seminal vesicle after the injection of lithium chloride at the doses of 100, 200 and 400 micrograms/100 g body weight/day for 7, 14 and 21 days. The studies indicate that 200 and 400 micrograms/100 g body weight for 14 days and 21 days showed a significant inhibition in the activity of acid phosphatase in all the above reproductive organs. There is a significant stimulation of alkaline phosphatase activity at the doses of 200 and 400 micrograms of lithium after 21 days of treatment in testis, prostate and seminal vesicle along with significant decrease in accessory sex organs weight in comparison to control animal. Therefore, it is evident that the effect of lithium on male reproductive organs mainly depends on the amount of the drug being injected and the duration of treatment to it.     

Influence of aqueous extract of Hibiscus sabdariffa L. petal on cadmium toxicity in rats

The effects of chronic exposure to cadmium (Cd) on some selected biochemical parameters, as well as the possible protective role of aqueous extracts of Hibiscus sabdariffa L petal were studied in 12-wk-old male Wistar albino rats. Exposure to Cd caused a significant increase in plasma l-alanine aminotransferases (ALT) only but with a corresponding decrease in liver l-alanine and l-aspartate aminotransferases (L-ALT, L-AST) when compared to the Cd-free control. Total superoxide dismutase activity was decreased in the liver, testis, and prostate of Cd-exposed rats, whereas malondialdehyde (MDA) concentrations were increased relative to the Cd-free control. The metal significantly increased prostatic acid phosphatase activity in the prostate, but decreased the body weight gain of the rats and organ/body weight ratio for prostate and testis compared to the Cd-free control. Pretreatment of rats with aqueous extract of H. sabdariffa resulted in significantly less hepatotoxicity than with Cd alone as measured by plasma ALT and liver ALT and AST activities. The extract also protected the rats against Cd-induced liver, prostate, and testis lipoperoxidation as evidenced by significantly reduced MDA values in these organs, as well as reduced prostatic acid phosphatase activity in the prostate, when compared to the Cd-only exposed rats. Also, when compared to the organ/body weight ratios obtained from rats exposed to Cd alone the prostate and testis were protected by the extract as shown by enhanced prostate/body weight and testis/body weight ratios of Cd- and extract-treated rats. These data suggest that H. sabdarrifa L might be protective in Cd toxicity.     

Tissue-specific cadmium accumulation and metallothionein-like protein levels during acclimation process in the Chinese crab Eriocheir sinensis

Aquatic organisms chronically exposed to cadmium can increase their resistance to a subsequent elevated exposure. In order to investigate mechanisms involved in acclimation process in the Chinese crab Eriocheir sinensis, we compared Cd level as well as metallothionein-like protein (MTLP) content in different tissues after direct acute exposure (i.e. 500 microg Cd L(-1) for 3 days), and after acute following chronic (i.e. 10 or 50 microg Cd L(-1) for 30 days) exposure. Cadmium accumulation occurred in the following order: anterior gill>hepatopancreas>posterior gill>carapace>hemolymph>muscle. As high concentrations as 188 microg Cd g(-1) w.w. were reported in anterior gills and seem to reach a saturation level. In these gills, the highest MTLP induction was observed after a direct acute exposure, for which a correlation with Cd content occurred. However, the Cd-binding potential by MTLPs was exceeded for any exposure condition. In hepatopancreas, the highest Cd level was reported for crabs acclimated during 30 days to 50 microg Cd L(-1) before challenging with an acute exposure. Moreover, we showed that MTLPs were induced during the acclimation process. In this organ, MTLPs are theoretically sufficient to bind all Cd. These results suggest that during a chronic exposure to 50 microg Cd L(-1), Chinese crabs acquire the capacity to hold more cadmium in hepatopancreas where it can be sequestrated by MTLPs. On the contrary, MTLP induction seems to be a rapid response to acute exposure in anterior gill, but is not sufficient to sequester all Cd. Other sequestration and/or detoxification mechanisms must take place in anterior gill to cope with high Cd levels.     

In vivo and in vitro effects of cadmium on selected enzymes in different organs of the fish Barbus conchonius Ham. (rosy barb).

1. Enzyme modulation by cadmium in selected organs of the fish, Barbus conchonius (rosy barb), was investigated in vivo (48 hr exposure to 12.6 mg/l cadmium chloride) and in vitro (10(-6) M cadmium chloride). 2. The acetylcholinesterase (AchE) activity was depressed in the gills but stimulated in the skeletal muscles and brain in vivo. The hepatic, branchial, and renal acid phosphatase (AcP) activity decreased marginally in vivo but it was significantly increased in the gut and ovary. In vitro, except for the liver, the AcP activity was depressed in the selected organs. Collaterally, gut alkaline phosphatase (AlP) was significantly inhibited but a pronounced stimulation was noted in the kidneys and ovary in vivo. In vitro, the AlP activity was conspicuously elevated in the kidneys and gut, and moderately in the gills. 3. Cadmium inhibited the glutamate-oxaloacetate and glutamate-pyruvate transaminases (GOT and GPT) in the liver, gills and kidneys in vivo. In vitro, the GOT and GPT activities were decreased in the liver, gills and kidneys. The lactic dehydrogenase (LDH) was significantly stimulated by Cd in the heart in vivo but in vitro the metal inhibited the enzyme in the gills. 4. Enzymes in the liver, followed by those in the kidneys and gills seem to be most seriously affected by Cd poisoning in this fish.     

Toxicological stress response and cadmium distribution in hybrid tilapia (Oreochromis sp.) upon cadmium exposure

Adult tilapia were exposed to 0 (control) and 4.45 microM Cd for 0 h, 5 h, 5 days, and 15 days, and the physiological responses of fish were described. The physiological responses were first expressed in gill tissue, in which mucus cells secretion increased, Cd accumulated, cortisol secretion was significantly higher, but serum ACH(50) activity (alternative complement hemolytic assay) was significantly lower than in controlled fish. After 5 days of Cd exposure, the ACH(50) activity showed a greater decrease, but lysozyme and cortisol contents showed significant increases over the control. Cd levels significantly increased in intestines, liver, and kidneys, and a significant induction of metallothionein (MT) protein in hepatic tissue was noted. Finally, the Cd accumulation rate still showed significant increases in these organs. However, the MT content was similar at 5 days and at 15 days after Cd exposure, and the cortisol contents had recovered to the pre-exposure level. In addition, Cd accumulation in muscle was higher after Cd exposure than in controls (t-test, p<0.05). Our results demonstrate (1) that tilapia readily regulate their physiological parameters in order to acclimate to a sublethal Cd environment; (2) these changes of physiological parameters may be related with a succession of cortisol levels following Cd exposure; (3) increasing rate of hepatic MT contents and Cd accumulation rate didn't appear identical after 5-15 days of Cd exposure. This was confirmed that hepatic MT was not a good indicator for Cd levels in tilapia.     

Immune responses and gene expression in hepatopancreas from Macrobrachium rosenbergii challenged by a novel pathogen spiroplasma MR-1008

Freshwater prawn Macrobrachium rosenbergii inoculated with 100 μl novel pathogen spiroplasma strain MR-1008 in logarithmic phase (10⁸ spiroplasmas ml^?1) were examined for alkaline phosphatase (AKP) activity, acid phosphatase (ACP) activity, superoxide dismutase (SOD) activity, catalase (CAT) activity, as well as expressions of 7 immune related genes in hepatopancreas after 1–28 d. Hematoxylin-eosin (HE) staining showed obvious pathological features in hepatopancreas connective and epithelial tissue. Enzyme activity analyze showed that hepatopancreas AKP and ACP activity increased markedly (P < 0.05) when inoculated with spiroplasma MR-1008 after 5 d and 10 d, respectively. SOD enzyme activity changed less obviously and slightly increased at 1 day post-inoculation, but CAT activity decreased significantly after 5 d inoculation. The expression levels of lipopolysaccharide and β-1,3-glucan-binding protein (LGBP), peroxinectin (PE), α2-macroglobulin (α2M), AKP, ACP, CAT, and copper/zinc SOD (Cu, Zn-SOD) genes in the hepatopancreas were examined by Real-Time PCR (qRT-PCR) and the results demonstrated that these immune related genes were induced by challenge with spiroplasma MR-1008. The results suggested that the prawn immune responses could be activated or inhibited by spiroplasma MR-1008, and that the hepatopancreas also plays key roles in innate immunity for defense against the pathogen.     

Induction of metallothionein-like proteins by mercury and distribution of mercury and selenium in the cells of hepatopancreas and gill tissues in mussel Mytilus galloprovincialis

The binding of mercury (Hg) to metallothioneins (MTs) and the relation between Hg and selenium in supernatants of hepatopancreas and gill tissues of the common mussel Mytilus galloprovincialis (Lamarck, 1819) was investigated. The mussels were exposed to different Hg concentrations in laboratory conditions: 2.5 μgHg/L, 4 d exposure (short term) and 60 μgHg/L, 33 d exposure (long term). In addition, the results were compared to those found for mussels from nature (polluted and unpolluted region). In control and short-term-exposed mussles, the level of Hg extraction (cytosol) from hepatopancreas and gill cells was very low with respect to the total Hg concentrations in the corresponding tissues, around 10% in control and around 20% after exposure. As expected, Hg exposure was followed by Se increase. For Se, the levels of extraction were higher, around 20% in control and up to 50% (heaptopacrease) of 70% (gills) after exposure. In order to study the distribution of Hg and Se in the cells of these organs, the total Hg and Secconcentrations were analyzed in the subcellular fractions obtained after differential centrifugation. Although after exposure the concentrations of both element increased in all subcellular fractions, their percentages in particular fractions were lower or higher. In this study, the convincing binding of Hg to metallothionein-like proteins was perceived after long-term laboratory exposure (gills, heapatopancreas) and in wild mussels collected near industrial port (hepatopancreas). In latter case, we also detected the traces of Se bound to the MT fractions after size-exclusion chromatography.     

Tissue ATPase activity and recovery in the freshwater crab Oziotelphusa senex senex exposed to a sublethal concentration of endosulfan for varying periods of time.

1. Na(+)-K+ and Mg(2+)-tissue ATPases of the freshwater crab Oziotelphusa senex senex showed increasing inhibition when exposed to a sublethal concentration (1.86 mg/l = 0.1 of LC50) of endosulfan for 1-30 days. 2. Na(+)-K(+)-ATPase activity in all tissues (thoracic nerve mass, gill, hepatopancreas and claw muscle) was higher than Mg(2+)-ATPase activity. 3. After 30 days exposure tissue Mg(2+)-ATPase was less affected than Na(+)-K(+)-ATPase. 4. Crabs exposed to endosulfan and then returned to uncontaminated water showed greater recovery of Mg(2+)-ATPase than Na(+)-K(+)-ATPase with 90-95% recovery after 1 day exposure and 60-65% recovery after 30 days exposure. 5. Changes in behaviour of the crabs were noted after 7 days exposure to endosulfan with progressive loss of coordination, decreased activity and increased exudation of mucus.     

Role of beta-carotene in ameliorating the cadmium-induced oxidative stress in rat brain and testis

The role of oxidative stress in chronic cadmium (Cd) toxicity and its prevention by cotreatment with beta-carotene was investigated. Adult male rats were intragastrically administered 2 mg CdCl2/kg body weight three times a week intragastrically for 3 and 6 weeks. Brain and testicular thiobarbituric acid reactive substances (TBARS) was elevated after 3 and 6 weeks of Cd administration, indicating increased lipid peroxidation (LPO) and oxidative stress. Cellular damage was indicated by inhibition of adenosine triphosphatase (ATPase) activity and increased lactate dehydrogenase (LDH) activity in brain and testicular tissues. Chronic Cd administration resulted in a decline in glutathione (GSH) content and a decrease of superoxide dismutase (SOD) and glutathione S-transferase (GST) activity in both organs. Administration of beta-carotene (250 IU/kg i.g.) concurrent with Cd ameliorated Cd-induced LPO. The brain and testicular antioxidants, SOD, GST, and GSH, decreased by Cd alone, were restored by beta-carotene cotreatment. Concurrent treatment with beta-carotene also ameliorated the decrease in ATPase activity and the increase in LDH activity in brain and testis of Cd-treated rats, indicating a prophylactic action of beta-carotene on Cd toxicity. Therefore, the results indicate that the nutritional antioxidant beta-carotene ameliorated oxidative stress and the loss of cellular antioxidants and suggest that beta-carotene may control Cd-induced brain and testicular toxicity.