Review articleInfluence of ethanol on lead distribution and biochemical changes in rats exposed to lead
Introduction
Lead constitutes a major environmental health hazard due to its pervasiveness in the environment and the awareness about its toxic effects at exposure levels lower than what was previously considered harmful. The toxicity of heavy metals is reported to be influenced by a wide range of nutritional, environmental and physiological factors. These factors such as malnutrition, alcoholism, age etc. may play an important role by regulating its absorption, distribution, and toxic manifestations (Grandjean, 1993). Ethanol is second only to water as the most important solvent in use today. Despite the multitude of problems related to it, the world-wide trend of alcohol consumption continues to rise (Samson & Harris, 1992). Ethanol has been shown to enhance carcinogenicity, mutagenicity, and hepatotoxicity of various chemicals Dhawan et al. 1992, McCoy et al. 1981. Ethanol, due to its ability to diffuse across biological membranes, may effect the absorption of various exogenous compounds and thus potentiate the toxic effects of several toxicants, including heavy metals such as lead. Higher blood lead levels have been reported in alcoholic industrial workers exposed to lead, compared to nonalcoholics indicating thereby that the former might be more prone to the toxic effects of this metal than nonalcoholics Cezard et al. 1992, Dalley et al. 1989. In a previous report from our laboratory by Pal et al. (1993), it has been shown that cadmium, which otherwise does not cross the blood brain barrier, accumulates in significantly higher levels and also enhanced neurotoxic effects of cadmium were observed when animals were coexposed to cadmium and ethanol. In a series of reports, Nation and his coworkers, it has been demonstrated that lead exposure attenuates the antitoxiceptive effects of ethanol, diminishes the rate depressant properties of the drug, and may attenuate the neurobehavioral effects of ethanol Grover et al. 1993, Nation et al. 1991. As the production and consumption of ethanol as well as environmental lead pollution are increasing rapidly, there is every likelihood of coexposure of industrial workers as well as general population to two neurotoxins (i.e., ethanol and lead). However, few reports are available on the effects of ethanol on lead induced biochemical changes. The present study was therefore, designed to examine the effect of ethanol on the distribution of lead in the body and various lead sensitive biochemical parameters in the blood of rats.
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Animals and treatments
Male albino rats (Wistar strain) weighing between 90–100 gm were procured from the animal house of PGIMER, Chandigarh. The animals were housed in polypropylene cages under hygienic conditions and fed standard rat pellet diet (Hindustan Lever Ltd., Bombay, India) and water ad libitum. After acclimatization for a period of 2 weeks, the animals were divided into 4 groups of 6–8 animals each. Different group of animals received the following treatments intragastrically under sterile conditions for
Results
Lead as well as ethanol (Table 1) independently resulted in a significant decrease in the net gain in body weight as compared to control animals. The gain in body weight of animals coexposed to lead and ethanol was considerably less compared to control as well as lead-treated animals. The brain weight of animals also decreased following respective treatments in all the groups; however, brain/body weight ratio was not changed following all treatments, thus indicating that lead and ethanol
Discussion
Exposure to lead as well as ethanol resulted in a significant decrease in the gain in body weight, which reduced further when animals were given lead and ethanol in combination. These results are supported by the work of Tandon and Tewari (1987) and Flora and Tandon (1987) who also reported significant weight loss after coexposure to cadmium and ethanol and lead and ethanol, respectively. As there was no significant change in the food intake of animals during any of the treatments, the decrease
Acknowledgements
The financial grant to V.G. for carrying out the present study was provided by the Postgraduate Institute of Medical Education and Research, Chandigarh, India.
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