Estrogen metabolism in the Asian elephant (Elephas maximus)
Publication Type: |
Journal Article |
Year of Publication: |
1992 |
Authors: |
N. M. Czekala, A. Roocroft, M. Bates, J. Allen, B. L. Lasley |
Publication/Journal: |
Zoo Biology |
Publisher: |
A Wiley Company, Inc., Wiley Subscription Services |
Keywords: |
estradiol conjugate, estradiol-17β, estrone |
ISBN: |
1098-2361 |
Abstract:
Abstract 10.1002/zoo.1430110203.abs Estradiol-17β metabolism was studied in two female Asian elephants (Elephas maximus). In an initial study, 500 μCi of tritiated estradiol-17β was injected iv into a single animal, and 0, 30 and 60 min serum samples were collected as well as all excreted urine and feces for 24 hr. In a second study, 1.5 mg unlabeled estradiol-17β was injected iv into a second animal and 0, 5, 15, 30, and 60 min serum samples and a 30 min urine sample were collected postinjection. Analyses of samples from both studies demonstrated a rapid conversion of free estradiol to conjugated forms in the serum. The first (5 min) serum sample following the injection of unlabelled estradiol contained unconjugated estradiol: conjugated estradiol: conjugated estrone at a ratio of 60: 29: 10, respectively, and at 30 min a ratio of 33: 43: 24. The urinary estrogen metabolites were in the conjugated form with an estradiol: estrone ratio of 60: 40. No radiolabeled estrogen was found in the fecal samples during the 24 hr following administration of the radiolabeled estradiol. These data indicate a rapid clearance of circulating free estradiol in the elephant, with a major metabolite in the serum and urine being estradiol conjugate. © 1992 Wiley-Liss, Inc.