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Adv. Pharmacol. Toxicol. 14 (2) 2013, 81-83 ISSN - 0973 - 2381 REVERSAL OF ENZYMES ACTIVITY BY CHELATING AGENT CAUSED BY MERCURY Ram Prakash Dept. of Zoology, Dr. A. G. D. Bendale Mahila Mahavidyalaya, JALGAON-425 001. Mercury is non-essential metal and caused neurological disorders in various forms. It is known not to excrete from neurological systems if once it has accumulated. It was reported highly toxic to plant and animal tissues. In present study it was applied to see its toxicity on some key enzymes in the kidney and later the remedies were recorded by using chelating agent methionine. Mercury was recorded to decrease the activity of four enzymes while post treatment of methionine was noted to reverse the status of enzymes towards normal values. INTRODUCTION Metals are categorized as essential and non essential. Essential metals play vital role in biological systems, while, whenever the non-essential metals entered in the cells/tissues/systems of the body, they manifest various disorders in the body, even sometimes the death of cell/ tissue/ organism. Mercury, a non essential metal is known to produce necrosis, cirrhosis, binucleated and multinucleated cells in liver. It was reported to cause a severe neurological disorder the Parkinson's disease ( Pavel Urbon, 2009, Rosini, et al., 2009). According to researchers, it is difficult to mobilize the mercury ions from neurons of brain. Therefore the care of Parkinson's disease is impossible. Magos (1998) reported three cases of methymercury poisoning in the workers in a plant producing mercuriacetate. Mercury was noted to disturbs neural cell adhesion molecules (NCAM) which are necessary for proper formation of interneuronal connections i.e. synatogenesis ( Dey, et al.1999). The dental mercury amalgam was also recorded as the source of mercury intoxication (Reinhardt1992). mercury manifests the polyneuopathy especially the nerve conduction (Lukas et al. 1992). Many efforts were made tnga`o reduce the body burdon of mercury by using someiu5; chelating agents and antioxidants. L-cysteine was found to associate with mercury ions to form the Me- Hg - L – Cysteine –complex to excrete to excrete mercury ion from the body to open channels for remedies. Similarly Me – Hg – glutathione was also reported for some purpose (Kerper et al. 1992, Baker et al. 1996). Amino acids transport system with leucine was positive to mobilize methyl mercury in rat ( Vojtisek, 2009). Keeping this view in mind we applied methionine to reduce body burden of mercury. The present results are showing therapeutic value and are encouraging for further work in this field. MATERIAL AND METHODS The albino rats of either sex were selected from laboratory stock. Six healthy were maintained under standard laboratory conditions and acclimatized for ten days. These were divided into three groups and housed in stainless steel cases separately. The rats of group I and II were administered methylmercury at 10mg / rat / kg body weight / day by gavage for * Corresponding Author
thirty days. The rats of III group were treated as control. After 30 days rats of group II were exposed with methionine (Loba) 4mg / rat / day for next 15 days. On the completion of scheduled treatment all rats were killed by decapitation. Both the kidneys were taken and homogenates were prepared in 0.25 M ice cold sucrose solution (10% w / v). During homogenization the temperature was maintained near 0?C. The homogenate were centrifuged for 20 minutes at 500 g and respective clear supernatant fluid was used as enzyme source. The activities of acid and alkaline phosphatase (Morton,1955) Cholinesterase (Rappaport, et al. 1959) and lipase (Bier, 1955) were determined Spectrophotometrically. Student 't' test was employed to calculate the statistical significance between control and experimental values. This experiment was carried out during research associateship of C.S.I.R. RESULTS Mercury was recorded to inhibit the activity of all targeted enzymes i. e. acid phosphatase, alkaline phosphatase, lipase and cholinesterase. However the values of all enzymes were reversed after the post exposure of methionine towards the control values. Results are significant and expressed in table 1. Table 1. Mean values of enzymes in the kidney of rat.
Values are significant at +P > 0.05 ++ P > 0.02 +++ P > 0.01 activity is expressed in mg of inorganic phosphate liberated / mg protein /hr at 37 ? C DISCUSSION Enzymes are long chain chemicals and play key role in the physiology and biochemistry of the living ones. They are capable to decrease or increase the rate of biological reactions acting as catalysts. The enzymological study in present piece of work shows that mercury deplete the activity of all key enzymes. The similar observations were reported by vojtisek in brain (vojtisek, 2009). Nandini (1989) also observed the decreased activity of these enzymes in liver of rat after the exposure of methylmercury. Methylmercury was removed from brain using L-Cysteine as it was bonded to from Me-Hg-L-Cystein complex. Similarly Me- Hg- glutathion complex was also reported (Vojtisek, 2009,Kerper, et al. 1992).The acid and alkaline phosphatase enzymes are marker for plasma membrane, golgi complex and mitochondria. Reversal of the values of these enzymes towards control values indicates its repair in living system. It also indicates the retention of methyl mercury from the kidney. Methionine is also expected to from complex on the pattern of Cystein, means to form Me - Hg-methionine complex because both are showing similar mechanism of retention. Alkaline Phosphatase is also known as cerebromicrovascular marker enzyme shows the positive results for leaky microvessels after use of L-Cystein against methylmercury intoxication (Vojtisek ,2009). However the histological lesions and increased total lipid values caused by methyl mercury
83 Reversal Of Enzymes Activity By Chelating Agent Caused By Mercury were reversed in the liver of rat (Nandini,1989).All there reports support the present observation, however it needs further research for its confirmation and the correctness. ACKNOWLEDGEMENT I am thankful to Dr. Sujata Gaikwad for her help in the preparation of this article. REFERENCES Bier M (1955). In: methods in Enzymology Vol.1 (Eds) S.P. Colowock and N.O.Kaplan. Academic Press . New York USA. Pavel Urban (2009) Health effects of Metals. Part -1 mercury. In: Metals and Neurotoxicity (Eds. M. Vojtisek and Ram Prakash ). Soc. For. Sci. Environ. India . 57 – 80. Rosini S.R. Reimao R., Lefevre B. H. and Medrado – Faria M. A. (2009). Chronic insomnia in workers poisoned by inorganic mercury. Arq. Neuropsiquiatr. 50. 32-38. Magos L. (1998). Three cases of methyl mercury intoxication which eluded correct diagnosis. Arch. Toxicol. 72, 701 – 705. Dey P. M., Gochfeld M and Reuhl K. R. (1999). Developmental methylmercury administration alters cerebellar PSA – NCAM expression and golgi salyltransferase activity. Brain Res. 845, 139 – 151. Reinhardt, J.W. (1992). Side effects: Mercury contribution to body burdon from dental amalgam. Adv. Dent. Res. 6, 110 -113. Lukas E, Urban P. Benicky L, Meseovieova E.(1992). Neurologicke a neurofyziologicke vysetoeni dilniku exponovanych param rtuti. Es. Neurol. Neurochir. 56. 202 – 203. Kerper L. E., Ballatori N. and Clarkson T. W. (1992). Methylmercury transport across the blood brain barrier by an amino acid carrier. Am. J. Physiol. 262. 761 -765. Vojtisek M.(2009). The blood brain barrier and metals. In: Metals and Neurotoxicity (Eds. Max Vojtisek and Ram Prakash). Society for science and Environment. India 1-55. Baker E. L., Feldman R. G., French J. G. (1990). Environmentally related disorders of the nervous system. Med. Clin. Nortl Am 74, 325 – 345. Nandini (1989). Influence of methionine on heavy metals (Mercury and Cadmium) Toxicity in rats. Ph. D Thesis – Meerut University, Meerut. Bharadwaj N. G. (1982). Effects of Dietary Cadmium and Zinc in liver and kidney of albino rats. Ph. D. Thesis. Meerut University, Meerut. Morton R. K. (1955) Methods in Extraction of enzyme from animal tissue. In : colowick S. P. and Kaplan N. O. (Eds). Methods in Enzymology Vol – 1,9, Academic Press. N. Y. USR. Rappaport F. Fischl I, and Pinto M. (1959) An improved method for the estimation of cholinesterase activity n serum, Clin. Chim. Acta. 4. 227 – 230. Rana S.V.S. Prakash R (1986). Collagen in the liver of metal fed rats. Exptl. Pathol. 29(1). 193 – 196.
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