Effects of chloroform and bromodichloromethane on DNA synthesis in male F344 rat kidney.

Abstract

We have been investigating the actions of chloroform (CHC13) and bromodichloromethane (BDCM) in rat kidney after different routes of exposure. Male F344 rats were exposed by gavage with corn oil or water as the diluting vehicle. All experiments lasted 30 days with gavage exposures 5 days per week for 4 weeks (20 doses). All animals were injected IP with bromodeoxyuridine (BrdU) 3 times over a 6-day period at 50 mg/kg/injection. Kidney tissue was fixed and slides were stained with hematoxylin and eosin for routine viewing and by the PAP (peroxidaseantiperoxidase) technique using anti-BrdU to label cells in DNA synthesis. There were no significant changes in gross parameters evaluated between the control rats and the rats exposed to CHCl3 or BDCM. Rats exposed via corn oil gavage to CHC13 displayed a segment-specific epithelial cell necrosis (6/6 high dose, 2/6 low dose). The lesions were primarily localized to the second segment of the proximal tubule, although some spread to cells in the first segment was occasionally observed. No histologic lesions were observed in the kidneys of rats exposed to BDCM.Preliminary results indicate a significant increase in DNA synthesis in the CHCI3-treated rats and a slight increase in DNA synthesis in BDCM-treated rats with corn oil as the diluent. The increase in BrdU labeling was primarily in cells of the S2 segment of the proximal tubule and interstitial cells of CHC13-exposed animals and in cells of the S3 segment of BDCM-exposed animals. The rats exposed using water as the vehicle did not show significant pathology (except for one rat in the high-dose CHC13 group, which had mild necrosis of proximal tubule epithelium). There were no changes in DNA synthesis in the CHCL3-treated rat kidneys when water was used as the vehicle. There was a slight increase in total DNA synthesis in the BDCM-treated rat kidneys, and the increase was mainly in the third segment of the proximal tubule. These data indicate differences in histopathologic alterations and levels of DNA synthesis that appear to depend on the vehicle that the chemicals were dissolved in and/or the route of administration. CHC13-induced pathologic alterations were more severe in the animals exposed by corn oil gavage. BDCM, an established renal carcinogen in rats, failed to induce any histopathologic alterations under the different experimental conditions of this study.

Formic acid excretion in rats and mice exposed to bromodichloromethane: a possible link to renal tubule cell proliferation in long-term studies

“…Only mild changes in renal morphology were seen at the top dose of 100 mg/kg/day in two rats and other markers of renal injury were within the normal range in both treated rats and mice. These findings are in good agreement with other studies with BDCM (Lipsky et al 1993) where renal injury is only seen at much higher doses (Condie et al 1983;NTP 1987;Thornton-Manning et al 1994). It would appear that the nephrotoxicity seen at these dose levels of BDCM in the chronic studies is the result of a low level, but sustained perturbation of the kidney, rather than frank acute cytotoxicity.…”

Factors That Can Influence Animal Research

“…Chlorine can cause alterations in the immune response or react with organic matter, man-made contaminants, bromide and iodide, resulting in the formation of carcinogenic, genotoxic, and mutagenic by-products (Exon et al, 1987;Hermann et al, 1982;Koivusalo and Vartiainen, 1997;Morris et al, 1992;Richardson et al, 2007). Chloroform, a trihalomethane, is found in relatively high concentrations in water and has demonstrated biological impact including cytotoxicity, increased DNA synthesis, and carcinogenesis (Lee et al, 1998;Lipsky et al, 1993;Vessel et al, 1976). Chloroform, a trihalomethane, is found in relatively high concentrations in water and has demonstrated biological impact including cytotoxicity, increased DNA synthesis, and carcinogenesis (Lee et al, 1998;Lipsky et al, 1993;Vessel et al, 1976).…”

Design and Management of Research Facilities

“…Fidler (1977) reported decreased in vitro activity of peritoneal macrophages when drinking water was chlorinated at 24-30 ppm. Chlorination of water containing organic matter results in the formation of by-products such as trihalomethanes, some of which, e.g., chloroform, may be cytotoxic, mutagenic, and/or carcinogenic (Lee et al, 1998;Lipsky et al, 1993;Morris et al, 1992;Pilotto, 1995). Therefore, chlorination of RO-treated water, which has fewer organic contaminants, is preferred.…”