Peroxisomes enzyme activity

Goldsworthy TL, Popp JA. 1987. Chlorinated hydrocarbon-induced peroxisomal enzyme activity in relation to species and organ carcinogenicity. Toxicol Appl Pharmacol 88 225-233. 

A 32% increase in liver weights, along with a 187% increase in peroxisomal beta-oxidation activity, was noted in rats exposed to 1,000 mg/kg/day MIL-H-5606 for 26 days (Mattie et al. 1993). The toxicological significance of the changes in peroxisomal enzyme activities is unclear. 

Rat 2 yr (Fischer- 344) (F) Hepatic 92 (induced peroxisomal enzyme activities) Cattley et al. 1987... 

Effect Currently there are no simple methods of measuring the effects of DEHP exposure. An increase in liver peroxisomes and peroxisomal enzyme activities appears to be the best marker of effect in rodents. This is not of great value in human studies since there is extensive evidence that humans, as well as primates, are refractory to peroxisome proliferators. Accordingly, research to identify reliable biomarkers for DEHP effects in humans would be useful in order to evaluate the prevalence and magnitude of exposure in an at-risk population. 

Goll V, Alexander E, Viollen-Abadie C, et al. 1999. Comparison of the effects of various peroxisome proliferators on peroxisomal enzyme activities, DNA synthesis, and apoptosis in rat and human hepatocyte cultures. Toxicol Appl Pharmacol 160 21-32. 

B. G. Lake, T. J. B. Gray, D. F. V. Lewis, J. A. Beamand, K. D. Hodder, R. Purchase, and S. D. Gangolli, Toxicol. Ind. Health, 3, 165 (1987). Structure-Activity Relationships for Induction of Peroxisomal Enzyme Activities by Phthalate Monoesters in Primary Rat Hepatocyte Cultures. 

Thottassery, J., Winberg, L., Youssef, J., Cunningham, M., and Badr, M. (1992). Regulation of perfluo-rooctanoic add-induced peroxisomal enzyme activities and hepatocellular growth by adrenal hormones. Hepatology 15, 316-322. 

Proliferation of peroxisomes and increases in peroxisomal enzymes have been reported in rat liver cells by several investigators (BIBRA 1986 Murakami et al. 1986a) at doses of 2,131 mg/kg/day for 21 days or more. In rats exposed for 13 weeks, induction of peroxisomal enzyme activity (acyl CoA oxidase) was... 

Chao et al. (2002) investigated peroxisomal P-oxidation activity, a major source of H2O2, as well as well as the peroxisomal anti-oxidant enzyme catalase, in male Fischer-344 rats of four age groups (4, 10, 50, and 100 week old). In the senescent group, the level of decline in both peroxisomal enzyme activities of 30% was surprisingly similar to the decline observed in the hepatic expression of the retinoid X receptor-a protein. 

Fig. 6.13. (A) Diagrammatic representation of the appearance of cucumber seedlings grown under a 12-12 h light-dark cycle. (B) Changes in glyoxysomal and peroxisomal enzyme activities in homogenates of cucumber cotyledons grown as in (A). Enzyme activity glyco-late oxidase ( ), nmol substrate consumed/min/cotyledon isocitrate lyase ( ), 0.1 x nmol substrate consumed/min/cotyledon malate synthetase (a), 0.04 x nmol substrate consumed/ min/cotyledon and catalase (x), 0.2 x units/cotyledon. After Trelease etal., 1971 [139]...

M (32% increase in liver weights 178% increase in peroxisomal beta-oxidation enzyme activity)... 

Di(2-ethylhexyl) phthalate (0, 0.5, 1, 2.5 or 5 g/kg per day) was administered to Fischer 344 rats by oral gavage from birth through lactation day 21 and the activity of several peroxisomal enzymes was determined in the livers, kidneys and brains of the females and their offspring (Cimini et al., 1994). No pups survived exposure to doses of 2.5 g/kg per day. Pup growth was impaired at the two lowest doses. In the liver, cyanide-insensitive palmitoyl-CoA oxidase activity showed similar increases in pups and adult females. 

Aoyama, T., Peters, J.M., Iritani, N., Nakajima, T., Furihata, K., Hashimoto, T. Gonzalez, F.J. (1998) Altered constitutive expression of fatly acid-metabohzing enzymes in mice lacking the peroxisome proliferator-activated receptor a (PPARa). J. biol. Chem., 213, 5678-5684... 

The VLCFA are produced in the peroxisomes. These cellular organelles do not show an appreciable variation of enzyme activities over the day or with age. Consequently, reliable reference values are available and it is our experience that approximately the same values are used in most experienced laboratories. 

Figure 5.36 Mechanism of the receptor-mediated induction of CYP4A by a chemical such as the drug clofibrate. The inducer-receptor (PPAR) complex enters the nucleus, binds with RXR, and the complex binds to the receptor response elements in the CYP gene. This induces the production of CYP4A mRNA, which leads to the production of CYP4A protein and functional enzyme. Alternatively, the drug may perturb lipid metabolism leading to increases in a lipid(s), which will bind to the receptor and cause the same response. Abbreviations PPAR, peroxisome proliterator-activated receptor RXR, retinoid X receptor.

PPAR peroxisome proliferator-activated receptor. Receptor involved in the induction of peroxisomal enzymes other responses to certain chemicals. 

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