Plasma protein changes in rats treated with hypolipidaemic drugs and with phthalate esters

Hepatic nuclear and cytoplasmic effects following intermittent feeding of rats with di(2-ethylhexyl) phthalate

The effects on rats of intermittent feeding with the peroxisome proliferator and hepatocarcinogen di(2-ethylhexyl) phthalate (DEHP) have been examined. Male Wistar rats were fed for alternate 7-day periods diets containing 20,000 ppm DEHP or the control diet. The rats were examined 3 days after the start or recommencement of administration of the DEHP-containing diet or after 7 days on the control diet. After the commencement or recommencement of feeding with DEHP the expected increases in liver weight and in the number of peroxisomes were found. The increase in liver: body-weight ratio in response to administration of DEHP-containing diets was greater in rats that had been previously exposed to the compound, but re-administration of DEHP had a less marked effect on the increase in peroxisome number. Morphometric analysis showed that administration of DEHP-containing diets resulted in an increase in cell number in the liver and that a fall in the cell number occurred after the rats had been returned to the control diet for 7 days. Analysis of nuclear size gave results consistent with an increase in tetraploid hepatocytes after treatment with DEHP which was reversed when the rats were returned to control diet.

Changes in plasma proteins in rats treated for short periods with hepatotoxins or with agents which induce cytochrome P450 isoenzymes

We have compared the alterations in plasma proteins following treatment of rats with the centrilobular hepatotoxin carbon tetrachloride, the periportal hepatotoxin allyl alcohol and two inducers of hepatic microsomal drug metabolising enzymes, phenobarbitone and a mixture of polychlorinated biphenyls (Aroclor 1254). The results are compared with changes observed in animals treated with agents which caused proliferation of rat liver peroxisomes and described in an earlier publication. Our results indicate that: There is a marked induction of a minor glycoprotein which migrates as a prealbumin following treatment with both inducers of microsomal mixed function oxidases and inducers of peroxisome proliferation. There is a marked increase in a minor alpha 1-glycoprotein when there is chemically-induced mitosis in the liver but not in mitosis following liver damage. Two major alpha 1-glycoprotein are depressed in all forms of liver damage. There are indications of specific protein responses to allyl alcohol, to inducers of microsomal mixed function oxidases and to inducers of peroxisome proliferation.