Metabolic changes induced by organophosphates in the piscine organs

Alterations in nitrogen metabolism in freshwater fishes, Channa punctatus and Clarias batrachus, exposed to a commercial-grade λ-cyhalothrin, REEVA-5

In the present study, two freshwater fishes Channa punctatus and Clarias batrachus were exposed to sub-acute concentrations of a commercial-grade λ-cyhalothrin, REEVA-5, for 96 h to observe the changes in amino acid catabolism under pyrethroid-induced stress and to investigate the comparative mechanisms of ammonia detoxification in both fishes. The experiments included the estimation of levels of free amino acid, urea, ammonia and the specific activities of aspartate aminotransferase (AAT), alanine aminotransferase (AlAT), glutamate dehydrogenase (GDH), glutamine synthetase (GS) and arginase in different vital organs of fishes. λ-cyhalothrin caused significant decline in the levels of amino acids along with simultaneous significant increase in the activity of AAT, AlAT and GDH, which indicated amino acid catabolism as one of the important mechanisms to meet out immediate energy demand of fishes. The level of ammonia was observed to be enhanced considerably at lower concentrations of λ-cyhalothrin while higher concentrations caused remarkable decline. The λ-cyhalothrin treatment resulted in significant increase in the activities of GDH and GS with concomitant increase in the activity of arginase and level of urea, indicating activation of two different mechanisms of ammonia detoxification. The mechanism of ammonia detoxification through its conversion into glutamate and glutamine was more prominent in C. punctatus, while C. batrachus demonstrated ureogenesis as the major route. In fishwise comparison, C. batrachus was observed to be more sensitive with respect to the above-mentioned parameters. Another important finding was that unlike the liver, the kidney appeared as one of the primary sites of ureogenesis in fishes.

Cypermethrin induced alterations in nitrogen metabolism in freshwater fishes

In the present study, two fresh water fishes namely, Channa punctatus and Clarias batrachus, were exposed to three sub-acute concentrations of synthetic pyrethroid, cypermethrin, for 96 h to evaluate the role of amino acids in fulfilling the immediate energy needs of fishes under pyrethroid induced stress as well as to find out the mechanism of ammonia detoxification. The experiments were designed to estimate the levels of free amino acid, urea, ammonia and the activities of aspartate aminotransferase (AAT), alanine aminotransferase (AlAT), glutamate dehydrogenase (GDH), glutamine synthetase (GS) and arginase in some of the vital organs like brain, gills, liver, kidney and muscle of both fish species. The significant decrease in the levels of amino acids concomitant with remarkable increase in the activities of AAT, AlAT and GDH in these vital tissues of fish species elucidated the amino acid catabolism as one of the main mechanism of meeting out the immediate energy demand of the fishes in condition of cypermethrin exposure. The levels of ammonia were significantly increased at 10% of 96 h LC(50) of cypermethrin in the different organs such as brain, gills, liver, kidney and muscle of both fish species while 15% and 20% concentrations of 96 h LC(50) of cypermehrin registered remarkable decline in both fish species. The differential increment in the activities of GDH, GS and arginase and in the level of urea established three different alternative mechanisms of ammonia detoxification. The results indicated that in C. punctatus, the prevalent mode of nitrogen excretion is in the form of conversion of ammonia into glutamine and glutamate while in C. batrachus, the excessive nitrogen is excreted in the form of urea synthesized from ammonia.

Toxicity studies of nonylphenol and octylphenol: hormonal, hematological and biochemical effects in Clarias gariepinus

Among the numerous chemicals discharged into aquatic ecosystems, nonylphenol (NP) and octylphenol (OP) have been shown to have a potent effect on the endocrine system of fish; this issue has been clearly dealt with in several studies. The objective of this study was to assess and compare the general toxicity of these estrogenic chemicals individually on Clarias gariepinus. Fish were exposed to different concentrations of both NP and OP (250, 500, 750 and 1000 μg l(-1) ) under semi-static conditions for a period of 7 days. The adverse effect was evaluated with use of blood cell counting, hemoglobin (Hb), hematocrit (HCT), hematimetric indices, bilirubin, protein, glucose, serum transaminases, serum phosphatases, lactate dehydrogenase and cortisol. The results showed a clear indication of anemia, increases in leukocyte count and bilirubin content and a reduction in plasma protein levels with higher concentrations of both the toxicants compared with controls. Furthermore, with all the concentrations the inevitable increase in serum cortisol and plasma glucose showed primary and secondary stress responses. Moreover, probable tissue damage gave rise to a series of fluctuations of enzyme levels at lower concentrations, but a decrease with higher concentrations showed the severity of the effect. Depending on the parameters examined, OP had a relatively greater effect than NP. Overall, these two chemicals seemingly affected hematology and the activity of some enzymes, leading to serious impairment of the metabolism and physiology of C. gariepinus.

Piroxicam-induced hepatic and renal histopathological changes in mice

Piroxicam is a non-steroidal anti-inflammatory drug widely used in rheumatic diseases. The aim of this study was to investigate Piroxicam-induced histopathological changes in livers and kidneys of male albino mice.

Cypermethrin-induced biochemical perturbations in freshwater fish Clarias batrachus at sublethal exposure and after released into freshwater

Cypermethrin-induced alterations in the fish, Clarias batrachus were studied. The fish were exposed to cypermethrin at a concentration of 0.07 mg/L for 10 days. After 10 days, fish were released into freshwater to observe the recovery response. At the end of 1, 5, and 10 days of exposure and after transfer into freshwater, different parameters were estimated in muscle and kidneys. Reduction in proteins was observed in both tissues, and recovery response was seen in muscle and kidneys. Free amino acid and ammonia content was enhanced in muscle and kidney for the 10 days. Transaminases (ALAT and AAT) and glutamate dehydrogenase activities were increased in both tissues for 10 days exposure span. Enzyme activities did not show much of the recovery.

Response of Cyprinus carpio (Linn) to sublethal concentration of cypermethrin: alterations in protein metabolic profiles

Freshwater fish, Cyprinus carpio were exposed to sublethal concentration (1.2 microg l(-1)) of cypermethrin for 6, 12, 24 and 48 h to analyze various parameters of protein metabolism in functionally different tissues. Total, structural and soluble proteins showed decrement; where as free amino acids and the activities of protease, aspartate aminotransferase and alanine aminotransferase significantly increased in cypermethrin exposed fish. Interestingly, ammonia content decreased but urea and glutamine increased at all periods of exposure. It was also observed that alterations steadily increased with the period of exposure and exhibited tissue specificity. Thus variation in the protein metabolism of the fish exposed to cypermethrin indicates its toxic effect on the cellular metabolism thereby leading to impaired protein synthetic machinery.

Prolonged effects of the insecticide dimethoate on locomotor behaviour in the woodlouse, Porcellio scaber Latr. (isopoda)

: Beneficial invertebrates living in hedgerows and woodland adjacent to arable land, are almost inevitably exposed to small doses of pesticides. This can present a threat to these invertebrates even at sublethal levels. Locomotor behaviour is intrinsic to many more complex behavioural responses such as predator avoidance, migration, mate seeking, etc., but is also closely related to the physiological status of the animal. Further, locomotor activity is quantifiable with the aid of modern video and computer technology. In the present study, the effect of a 48 h exposure of the woodlouse Porcellio scaber to soil contaminated with one-tenth of the LD20 (96 h) dimethoate dose was quantified using computer-automated video tracking. Dimethoate-exposed woodlice were recorded for one night prior to dimethoate exposure and for two nights on contaminated soil. After a recovery period of 21 days, the woodlice were recorded for a further night. Control animals were recorded in parallel on soil treated with water. Over the 48 h of exposure, dimethoate induced a gradually increasing hyperactivity in terms of time spent in activity, mean velocity and path length and a suppression of turning rate when compared with controls. No recovery was seen after the 21 days on uncontaminated soil. These effects were statistically significant only in male woodlice.