Sunil Kumar Srivastav

N-acetyl cysteine and selenium protects mercuric chloride-induced oxidative stress and antioxidant defense system in liver and kidney of rats: A histopathological approach

Mercury exposure is second-most common cause of metal poisoning which is quite stable and biotransformed to highly toxic metabolites thus eliciting biochemical alterations and oxidative stress. The aim of present study describes the protective effect of selenium either alone or in combination with N-acetyl cysteine (NAC) against acute mercuric chloride poisoning. The experiment was carried out in male albino Sprague Dawley rats (n=30) which was divided into five groups. Group 1 served as control. Groups 2-5 were administered mercuric chloride (HgCl2: 12mol/kg, i.p.) once only, group 2 served as experimental control. Animals of groups 3, 4 and 5 were received N-acetyl cysteine (NAC: 0.6mg/kg, i.p.) and selenium (Se: 0.5mg/kg, p.o.) and NAC with Se in combination. Acute HgCl2 toxicity caused significant rise in serum alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase, albumin, bilirubin, γ-glutamyl transpeptidase, cholesterol, triglycerides, protein, urea, creatinine, uric acid and blood urea nitrogen content. Animals also showed significantly higher mercury content in liver and kidney, significant rise in lipid peroxidation level with concomitant decrease in reduced glutathione content and the antioxidant enzyme activities of superoxide dismutase and catalase after HgCl2 exposure. Results of the present investigation clearly showed that combination therapy with NAC+Se provide maximum protection against mercury toxicity than monotherapy (alone treated groups) by preventing oxidative degradation of biological membrane from metal mediated free radical attacks.

Effects of deltamethrin on serum calcium and corpuscles of Stannius of freshwater catfish, Heteropneustes fossilis.

Catfish, Heteropneustes fossilis, were subjected to deltamethrin for short-term (96 h; 1.49 μg L−1) and long-term (28 days; 0.37 μg L−1) durations. The effects of deltamethrin exposure were evaluated on the corpuscles of Stannius (CS) of the fish, as it has been reported recently that stanniocalcin homologs are present in fish as well as in tetrapods, including human beings. Moreover, in addition to their role in mineral homeostasis, stanniocalcin proteins also play a significant role in metabolism, reproduction, and development. Serum calcium levels of deltamethrin-treated fish decreased from 48 to 96 h in the short-term, and from day 7 to day 28 in the long-term experiment. The aldehyde fuchsin-positive (AF-positive) cells of CS of deltamethrin-treated fish exhibited increased granules after 72 and 96 h. No change was noticed in the nuclear volume of AF-positive cells. The AF-negative cells of CS depicted an increased nuclear volume after 96 h of deltamethrin treatment. The AF-positive cells of CS of long-term deltamethrin-treated fish exhibited increased granulation after 21 and 28 days. The nuclear volume of these cells depicted a progressive decrease from 14 days until the end of the experiment. The nuclear volume of AF-negative cells exhibited an increase at 21 and 28 days.

Histological alterations in the prolactin cells of a teleost, Heteropneustes fossilis, after exposure to cypermethrin

Freshwater fish Heteropneustes fossilis (H. fossilis) were subjected to 5.76 μg/L (80% of 96 h LC50) and 1.44 μg/L (20% of 96 h LC50) of cypermethrin for short‐term (96 h) and long‐term (28 days) duration, respectively. Plasma calcium of H. fossilis exposed for short term (96 h) to cypermethrin exhibited no change at 24 h. The levels indicate a decrease in plasma calcium at 48 h. This response persists till the close of experiment (96 h). No change has been noticed throughout the experiment in the histological structure and nuclear volume of prolactin cells of short‐term cypermethrin treated fish. Long‐term exposure of cypermethrin to fish provoked hypocalcemia. The prolactin cells remain unchanged till 7 days following cypermethrin treatment. After 14 days, the nuclear volume exhibits an increase and the cells exhibit degranulation. These changes increase progressively 21 days onwards. Also, few degenerating cells are discerned after 28 days.

Deltamethrin-induced alterations in serum calcium and prolactin cells of a freshwater teleost, Heteropneustes fossilis

Deltamethrin, a pyrethroid insecticide widely used in many countries, causes significant adverse effects in aquatic ecosystems. The concentration of deltamethrin in water reservoirs and the run off from agricultural areas (in water) in many countries range up to 24.0 µg L−1 which is higher than the recommendation of the European Union standard. Hence, in this study the effects of deltamethrin were investigated, i.e. its toxic impacts on the freshwater catfish Heteropneustes fossilis in terms of serum calcium and prolactin cells (located in the rostral pars distalis region of the pituitary). The fish were subjected to deltamethrin for a short-term experiment (96 h; 1.5 µg L−1 e.0.8 of 96 h LC50) and a long-term experiment (28 days; 0.37 µg L−1 e.0.2 of 96 h LC50). After short-term deltamethrin exposure, serum calcium levels decrease. No histological change in prolactin cells is noticed throughout the short-term experiment. Fish exposed to deltamethrin for 7 days also exhibit a decrease in serum calcium level. This decrease persisted until the end of the experiment (28 days). Prolactin cells of fish treated for 14 days with deltamethrin exhibit increased nuclear volume and degranulation, increasing progressively from the 21st day onwards. After 28 days, a few degenerated cells are discerned. The results of this study show that deltamethrin is moderately toxic for the freshwater fish H. fossilis by producing adverse effects on serum calcium and prolactin cells. Hence, it should be used with caution in areas near fish-inhabited waters.

Toxicity of aqueous extract of Euphorbia tirucalli latex on catfish, Heteropneustes fossilis.

A four-day static renewal acute toxicity test was performed to determine the LC(50) value of aqueous extract of Euphorbia tirucalli latex for the freshwater fish, Heteropneustes fossilis. The LC(50) values, their upper and lower confidence limits and slope functions were calculated. The LC(50) values for aqueous extract of E. tirucalli latex at various exposure periods are 3.450 μl/L for 24 h, 2.516 μl/L for 48 h, 1.623 μl/L for 72 h and 1.315 μl/L for 96 h. The toxicity of aqueous extract of E. tirucalli latex exhibits a positive correlation between fish mortality and exposure periods. It is concluded that latex of E. tirucalli has higher piscicidal activity as compared with other synthetic pesticides, organophosphates and pyrethroids for the fish H. fossilis. Hence, adequate precautions must be exercised when E. tirucalli latex is being used near fish-inhabiting water reservoirs.

Ultimobranchial gland of a freshwater teleost, Heteropneustes fossilis, in response to cadmium treatment.

Heteropneustes fossilis were subjected to 288 mg/L (0.8 of 96 h LC50) and 72 mg/L (0.2 of 96 h LC50) of cadmium chloride for short‐term and long‐term experiments, respectively. After sacrificing the fish, the blood was collected on 24, 48, 72, and 96 h in short‐term and after 7, 14, 21, and 28 days in long‐term experiment and analyzed for plasma calcium levels. Also, ultimobranchial glands were fixed on these intervals. The plasma calcium levels of short‐term cadmium‐exposed fish remain unchanged after 24 h. The levels exhibit a progressive decrease from 48 h onwards. The fish exposed to cadmium for 7 days exhibit a decrease in the plasma calcium level. Thereafter, the levels progressively decrease till the end of the experiment (28 days). Up to 72 h exposure of the fish to cadmium, the ultimobranchial gland exhibits no histological change. After 96 h, a decrease in the staining response of the cytoplasm of ultimobranchial cells has been noticed. The nuclear volume of these cells records a slight decrease. Up to 14 days of cadmium exposure, there is no change in the histological structure of ultimobranchial gland. After 21 days following the exposure, the ultimobranchial cells exhibit a slight decrease in the staining response of the cytoplasm and the nuclear volume of these cells records a decrease. Following 28 days cadmium exposure the nuclear volume exhibits a further decrease, and degeneration and vacuolization sets in.

Methylmercury toxicity: amelioration by selenium and water-soluble chelators as N-acetyl cysteine and dithiothreitol

The protective potential of chelators, i.e. N‐acetyl cysteine (0.6 mg /kg, intraperitoneally) and dithiothreitol (15.4 mg kg−1, intraperitoneally) with selenium (0.5 mg kg−1, pre‐oral) were evaluated individually and in combination against methylmercury‐induced biochemical alterations and oxidative stress consequences. Forty‐two male Sprague–Dawley rats were exposed with methylmercury (1.5 mg kg−1, pre‐oral) daily for 21 days followed by different treatments for five consecutive days. Administration of methylmercury caused significant enhancement in the release of transaminases, alkaline phosphatases and lactate dehydrogenases in serum. A significant increased was observed in lipid peroxidation level with a concomitant decreased in glutathione content after methylmercury exposure in liver, kidney and brain. Hepatic microsomal drug metabolizing enzymes (aniline hydroxylase and amidopyrine N‐demethylase) of cytochrome p4502E1 showed sharp depletion after methylmercury exposure. Alterations in histological changes in liver, kidney and brain were also noted in methylmercury administered group. All treated groups showed recovery pattern, but the combined treatments with N‐acetyl cysteine and dithiothreitol in combination with selenium were more effective than that with either alone treatments in recovering blood biochemical changes after methylmercury toxicity. In conclusion, the results demonstrated that combination therapy may recover all blood biochemical alterations and offer maximum protection against methylmercury‐induced toxicity. Copyright

Effects of Euphorbia tirucalli latex on blood calcium and phosphate of the freshwater air-breathing catfish Heteropneustes fossilis

The effects of Euphorbia tirucalli latex on blood calcium and phosphate of Heteropneustes fossilis was investigated in this study. The fish were subjected to 0.8 of 96-h LC50 value of E. tirucalli latex (1.05 µL L−1) for 96-h in a short-term experiment and 0.2 of 96-h LC50 value (0.263 µL L−1) for 28 days in a long-term experiment. Fish were sacrificed after 24, 48, 72, and 96 h in the short-term experiment and after 7, 14, 21, and 28 days in the long-term experiment and blood samples were analyzed for calcium and inorganic phosphate. Acute exposure of E. tirucalli latex caused a progressive decrease in the calcium level after 48 h which persists till the close of the experiment. Phosphate levels remain unaffected till 48 h but after 72 h the levels exhibit a progressive decrease. Chronic E. tirucalli latex treatment provokes a decrease in calcium levels at day 7 continuing till the end of the experiment (28 days). The phosphate levels remain unaffected up to day 7, thereafter, levels decrease from 14 days till the end of the experiment.

Blood electrolytes of the freshwater catfish Heteropneustes fossilis in response to treatment with a botanical pesticide (latex of Euphorbia royleana)

The aim of the present study was to determine changes in blood electrolytes (calcium and phosphate) in the freshwater catfish Heteropneustes fossilis following short- and long-term exposure to latex of Euphorbia royleana. To investigate the effects of short-term exposure, fish were exposed to 80% of the 96-h LC(50) of E. royleana latex (2.47 mg/L) for 96 h. To assess the effects of long-term exposure, fish were exposed to 20% of the 96-h LC(50) of E. royleana latex (0.618 mg/L) for 28 days. Fish were killed after 24, 48, 72 and 96 h (short-term experiments) or after 7, 14, 21 and 28 days (long-term experiments). Blood samples were collected and sera were analyzed to determine calcium and inorganic phosphate levels. Serum calcium levels decreased progressively in H. fossilis after 48 h exposure to E. royleana latex. This decrease persisted until the end of the experiment (96 h). Serum inorganic phosphate levels in treated fish decreased progressively from 72 h. After 7 days exposure to E. royleana latex, decreased serum calcium levels were noted in H. fossilis that persisted until the end of the experiment. Serum phosphate levels were decreased in H. fossilis on days 21 and 28 of exposure to E. royleana latex. It is concluded that E. royleana latex alters the blood electrolyte content of the fish. The change in these electrolytes, particularly calcium levels, may cause disturbances in the normal vital physiological functions of the fish, its growth rate, and even its ability to survive in nature.

Effects of lead on the plasma electrolytes of a freshwater fish, Heteropneustes fossilis

The freshwater catfish, Heteropneustes fossilis, was subjected to 657.6 mg/L (0.8 of 96 h LC50) and 164.4 mg/L (0.2 of 96 h LC50) of lead nitrate for short-term and long-term experiment, respectively. Blood from fish was collected on 24, 48, 72 and 96 h in short term and after 7, 14, 21, and 28 days in long-term experiment. Plasma calcium and phosphate levels were determined at these intervals. After short-term lead exposure, the plasma calcium levels of the fish remained unaffected at 24 h. The levels exhibited a decrease after 48 h which persisted until the end of the experiment (96 h). Following 48 h of lead exposure to the fish, the plasma phosphate levels remained unchanged. The values exhibited a progressive decrease from 72 h onwards. The plasma calcium levels of the fish exposed to lead for 7 days exhibited a decrease. This decrease persisted progressively until the end of the experiment (28 days). The plasma phosphate levels of lead-exposed fish remained unaffected until day 14. The levels decreased progressively from 21 days onwards.