Endocrine Abstracts

Introduction: Only few studies were observed, supporting the hypothesis that the administration of high doses of vitamin E in people with elevated serum total cholesterol levels leads to increased adrenocortical hormone secretion. There are only limited data concerning androgen or estrogen levels. The aim of this study is to investigate the possible effect of Vitamin E on adrenal and sex hormones in rabbits with hypercholesterolemia, as an animal model for the research.

Methods: The study was designed with 4 rabbits, 2 males and 2 females. High cholesterol diet was administered to all subjects for 13 days. When total cholesterol levels were ≥597 mg/dl high cholesterol diet was discontinued. We administered vitamin E 1000IU on the study group (1 female and 1 male rabbit, subject 1 and 2 respectively) for 30 days while female subject 3 and male subject 4 did not receive any supplement. Serum samples were tested at baseline when high total cholesterol levels were achieved and 2, 4, 5, 10, 20, 30 after vitamin E supplementation for total cholesterol, SGPT, gGT, estradiol, testosterone, cortisol and DHEA. The animals were then euthanized and were sent for histological examination.

Results: The initial measurements of liver enzymes were: SGPT=50 IU/l for subject 1, 60 IU/l for subject 2, 47 IU/l for subject 3 and 56 IU/l for subject 4 and gGt= 16 U/l, 20 U/l, 17 U/l, 15 U/l respectively. After vitamin E supplementation SGPT values were 32 IU/l, 35 IU/l, 38 IU/l, 32 IU/l and gGt 6 U/l, 4 U/l, 5 U/l, 4 U/l for each subject respectively. Plasma morning cortisol levels at baseline were 45 mg/dl, 9.49 mg/dl, 1.33 mg/dl, 1.72 mg/dl demonstrating a wide variance in the subsequent measurements, reaching 754 mg/dl for subject 1 on the fifth day of vitamin E administration. Testosterone levels at baseline were 0.0636 ng/dl, 5.58 ng/dl, 0.0933 ng/dl, 5.53 ng/dl and after supplementation 0.0497 ng/dl, 7.49 ng/dl, 0.0783 ng/dl, 6.71 ng/dl. Interestingly, testosterone and DHEA levels increased acutely only in female rabbits, the first day after administration of vitamin E. Estradiol levels at baseline were 13 pg/ml, 8.47 pg/ml, 11.3 pg/ml, 13.2 pg/ml and after supplementation for 30 days 1.84 pg/ml, 11.7 pg/ml, 4.4 pg/ml 4.54 pg/ml.

Conclusions: Administration of high dose vitamin E in female rabbits with hypercholesterolemia increases testosterone and DHEA levels, but not estrogen levels. Further studies are needed to support or verify a claim.