Modulation (feminization) of hepatic enzymes by an ectopic pituitary tumor.
The ontogeny and endocrine regulation of sex-differentiated hepatic metabolism is mediated via the hypothalamic-pituitary axis. Using in vitro-in vivo systems, we demonstrate alterations in activity levels of six sex-differentiated enzyme systems in male rats bearing ectopic pituitary tumors after the injection of a pituitary cell line, C811RAP. Activity levels of hepatic glutathione S-transferase, UDP-glucuronyltransferase, and aryl hydrocarbon hydroxylase are reduced to activity levels of control females, while histidase, 5 alpha-reductase, and serum cholinesterase levels are increased to levels of control females, i.e. feminization of all of these enzymes. RIAs of testosterone, estrogen, FSH, and PRL are similar in tumor-bearing and control animals, but GH levels are significantly higher in tumor-bearing animals than in the controls. It is suggested that GH may be the pituitary factor responsible for the expression of sex-differentiated hepatic metabolism.
D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase / Q000378:metabolism; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism; D002460:Cell Line; D002802:Cholinesterases / Q000097:blood; D003600:Cytosol / Q000201:enzymology; D004967:Estrogens / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D014453:Glucuronosyltransferase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D013006:Growth Hormone / Q000097:blood; D006638:Histidine Ammonia-Lyase / Q000378:metabolism; D008099:Liver / Q000201:enzymology*; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology; D010911:Pituitary Neoplasms / Q000201:enzymology / Q000503:physiopathology*; D011388:Prolactin / Q000097:blood; D051381:Rats; D011919:Rats, Inbred Strains; D012737:Sex Factors; D013739:Testosterone / Q000097:blood
D004967:Estrogens; D013739:Testosterone; D011388:Prolactin; D005640:Follicle Stimulating Hormone; D013006:Growth Hormone; D001189:Aryl Hydrocarbon Hydroxylases; D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase; D014453:Glucuronosyltransferase; D005982:Glutathione Transferase; D002802:Cholinesterases; D006638:Histidine Ammonia-Lyase