Serum enzymes, rats exposed

Elevated activities of liver enzymes (lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, glutamate dehydrogenase) were found in the serum of rats exposed continuously to 26 ppm phenol vapor for 15 days (Dalin and Kristoffersson 1974). Increased concentration of these enzymes in serum is often associated with liver injury but is not conclusive evidence for the type or severity of injury. Therefore, 26 ppm can be considered a less serious LOAEL in rats. Serum levels of... 

Serum (3-glucuronidase activity was increased in a dose-related manner when disulfoton was given intraperitoneally to rats (Kikuchi et al. 1981). In the same study, this effect was not observed in mice, rabbits, or guinea pigs. This enzyme appears to be a useful biomarker of hepatic function in rats exposed to disulfoton, but may not be a useful biomarker in humans. 

Thyroid effects that have mainly included reduced serum T4 hormone levels and follicular cell hyperplasia were consistently observed in rats and mice orally exposed to PBDEs. Accompanying changes in serum TSH levels were not found and the depression of serum T4 is likely related to hepatic enzyme induction. Acute duration studies showed decreases in serum T4 in rats exposed to >10 mg/kg/day octaBDE or >30 mg/kg/day pentaBDE for 4 days and in rats and mice exposed to >18 mg/kg/day pentaBDE for 14 days. Effects observed in intermediate-duration studies include thyroid hyperplasia in rats exposed to >8 mg/kg/day octaBDE for 30 days and reduced serum T4 in rats exposed to >10 mg/kg/day pentaBDE for 90 days. Exposure to pentaBDE on gestation day 6 through postnatal day 21 caused serum T4... 

Aroclor 1254 for durations as short as 1-3 days (Bruckner et al. 1977) no other hepatic end points were evaluated in this study. Relative liver weight and serum total cholesterol were increased in rats that were fed estimated doses of i mg/kg/day Aroclor 1254 for 4 days, but not 0.5 mg/kg/day (Carter 1984, 1985) histology was not evaluated. Acute-duration studies evaluating hepatic effects of PCBs other than microsomal enzyme induction at doses lower than those in the Carter (1984, 1985) studies were not located. Effects in rats exposed to higher doses of PCBs in acute-duration studies included increased liver weight, decreased Uver glucose 6-phosphatase, and/or decreased serum cholesterol at... 

Frosolono and Pawlowski (1977) studied biochemical changes in various lung fractions prepared from rats exposed to phosgene at concentrations near to or above the LCtso. A number of enzymes showed decreased activity in all fractions these included p-nitrophenyl phosphatase, cytochrome c oxidase, ATPase and lactate dehydrogenase (LDH). The serum LDH rose. It was suggested that either inhibition of enzyme activity or loss of enzyme from cells would account for these changes. The data available did not allow... 

Relative liver weight was not affected in rats exposed to 50 mg/m di- -butyl phthalate mist 6 hours/day for 6 months (Kawano 1980a). Small fluctuations in several serum chemistry parameters (serum enzymes, urea nitrogen, cholesterol) were noted in this study, but these were not clearly dose- or time-dependent. 

Hepatic Effects. Workers monitored for liver function had increased serum levels of liver enzymes (Hoogendam et al. 1965). Only limited conclusions should be drawn from these results as the levels returned to normal within 1 week to 3 months concurrent exposure to other chemicals and alcohol was not controlled. Diffuse degenerative hepatic lesions were observed in rabbits and mice exposed to lethal doses of endrin and in surviving animals (Treon et al. 1955). Rats, mice, guinea pigs, and hamsters administered a relatively high dose of endrin exhibited moderate hepatic histopathology (Hassan et al. 1991). 

Hepatotoxicity, characterized histologically by centrilobular necrosis, and elevated hepatic enzymes in serum were reported in separate studies in which laboratory animals were exposed to phenol in air at concentrations 26 ppm (Dalin and Kristoffersson 1974 Deichmann et al. 1944). Hepatic effects were not observed in monkeys, rats, or mice exposed to 5 ppm phenol in air continuously for 90 days (Sandage 1961). Hepatic effects have also not been observed in rodents following oral exposure to phenol (Berman et al. 1995 Hsieh et al. 1992 Jones-Price et al. 1983a, 1983b NCI 1980). 

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