Related Experiment Video
Updated: May 6, 2026

Author Spotlight: Investigating the Mechanisms and Inducing Models of Polycystic Ovary Syndrome
Published on: July 5, 2024
The effect of ovariectomy on phenylalanine and tyrosine metabolism
1Department of Paediatrics, University of Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria.
Abstract:
Although the regulatory activity of steroid hormones on amino acid metabolism has been described, no information is published on the effect of ovariectomy. We studied the influence of ovariectomy in Wistar rats determining the amino acids phenylalanine and tyrosine in liver, kidney, plasma and urine. 32 animals were used in the study, 12 animals were sham operated, 9 animals were ovariectomized and 11 rats were ovariectomized and supplemented with estradiol. No quantitative changes were detected comparing liver and kidney phenylalanine and tyrosine between the groups (sham operated rats liver phenylalanine 2,53nM/mg ± 1,07; liver tyrosine 1.95nM/mg ± 0.92; kidney phenylalanine 2.16nM/mg ± 0.53; kidney tyrosine 1.80nM/mg ± 0.39. Ovariectomized rats showed liver phenylalanine 3.07nM/mg ± 1.14; liver tyrosine 2.63nM/mg ± 1.01; kidney phenylalanine 2.30 nM/mg ± 0.74; kidney tyrosine 1.93nM/mg ± 0.63. Ovariectomized and estradiol supplemented rats presented with liver phenylalanine 2.84nM/mg ± 1.40; liver tyrosine 2.35nM/mg ± 1.28; kidney phenylalanine 1.91nM/mg ± 0.26, kidney tyrosine 1.67nM/mg ± 0.23.). When, however, the phenylalanine/tyrosine ratio in the liver was evaluated, ovariectomized rats showed a significant decrease of the quotient (p = 0.001). The phenylalanine/tyrosine ratio was restored by estradiol replacement. Our findings show that phenylalanine and tyrosine metabolism is under estradiol control. The effect on the metabolic changes could be mediated by enzyme systems as phenylalanine hydroxylase, tyrosine hydroxylase and tyrosine aminotransferase. Our results would be compatible with previous reports on the stimulatory effect of estradiol on these enzymes. The kidney phenylalanine/tyrosine ratio was unaffected by ovariectomy and/or estradiol replacement which can be easily explained by different pools, enzyme activities, filtration/reabsorption effects, etc.The urinary P/T ratio was decreased by ovariectomy and restored by estradiol replacement indicating endocrine control of renal reabsorption and secretion mechanisms.
More Related Videos
06:18An In Vivo Estrogen Deficiency Mouse Model for Screening Exogenous Estrogen Treatments of Cardiovascular Dysfunction After Menopause
Published on: August 13, 2019
14:26A Method to Study the Impact of Chemically-induced Ovarian Failure on Exercise Capacity and Cardiac Adaptation in Mice
Published on: April 7, 2014
Related Concept Videos
Effect of Hepatic Disease on Pharmacokinetics: Pathophysiologic Assessment and Liver Function Test
Effect of Hepatic Disease on Pharmacokinetics: Active Drug, Metabolite and Fraction of Metabolized Drug
Inborn Errors of Metabolism
Phase I Reactions: Oxidation of Aliphatic and Aromatic Carbon-Containing Systems
Oxidation reactions are fundamental in aromatic carbon-containing systems. An example is the hydroxylation of phenobarbital, a process that transforms it into...
Effect of Hepatic Disease on Pharmacokinetics: Drug Dosing and Hepatic Blood Flow
Effect of Hepatic Disease on Pharmacokinetics: Dose Adjustments Due to Hepatic Impairment