Unknown

Dataset Information

0

Steroid glucuronyltransferases of rat liver. Properties of oestrone and testosterone glucuronyltransferases and the effect of ovariectomy, castration and administration of steroids on the enzymes.


ABSTRACT: 1. Microsomal preparations from rat liver, kidney and intestine were tested for UDP-glucuronyltransferase activity by using oestrone, oestradiol-17 beta, oestriol, testosterone, cortisol, cortisone, corticosterone, aldosterone, tetrahydrocortisol and tetrahydrocortisone as substrates. The microsomal preparation from the liver glucuronidated oestrone, oestradiol-17 beta and testosterone. 2. The specific activity of the enzyme was significantly higher in livers from female rats than in those from male rats. 3. Testosterone was actively glucuronidated by both sexes. Cortisol, cortisone, corticosterone, aldosterone, tetrahydrocortisol and tetrahydrocortisone were not glucuronidated by any of the three tissues. 4. The non-ionic detergent Lubrol WX activates liver microsomal UDP-glucuronyltransferase 2-3-fold with oestrone and testosterone as substrates. 5. Oestrone glucuronyltransferase was inhibited by oestradiol-17 beta, predominantly competitively and by testosterone non-competitively. Bilirubin was a non-competitive inhibitor of oestrone glucuronidation. p-Nitrophenol had no effect. 6. Oestrone glucuronyltransferase could not be stimulated by either acute or prolonged treatment of animals with phenobarbital, whereas a single dose of 3-methylcholanthrene led to a moderate stimulation. 7. Ovariectomy leads to a 56% decrease in oestrone glucuronyltransferase activity; administration of oestradiol-17 beta induces the enzyme to normal activity after 12 days, and after 15 days the activity is twice the control value. Actinomycin D and cycloheximide block the oestradiol-17 beta-induced increase in enzyme activity. 8. Castration has no effect on the activity of testosterone glucuronyltransferase, nor does administration of testosterone influence enzyme activity. The results provide strong evidence for the existence of multiple steroid glucuronyltransferases in the liver of the rat.

SUBMITTER: Rao GS 

PROVIDER: S-EPMC1164637 | BioStudies | 1977-01-01

SECONDARY ACCESSION(S): 10.1042/bj1620545

REPOSITORIES: biostudies

Similar Datasets

1980-01-01 | S-EPMC1162010 | BioStudies
2018-01-01 | S-EPMC6462871 | BioStudies
1973-01-01 | S-EPMC1177583 | BioStudies
1972-01-01 | S-EPMC1173769 | BioStudies
1985-01-01 | S-EPMC1144567 | BioStudies
1979-01-01 | S-EPMC1161055 | BioStudies
1980-01-01 | S-EPMC1162200 | BioStudies
1968-01-01 | S-EPMC1187113 | BioStudies
1983-01-01 | S-EPMC1152275 | BioStudies
1979-01-01 | S-EPMC1186595 | BioStudies