THE EFFECT OF ESTRADIOL ON THE FREE AMINO ACIDS OF THE RAT UTERUS

¹ Department of Pharmacology, Stanford University School of Medicine, Palo Alto, California

At periodic time intervals up to 30 hours after the intravenous injection of 2 µg of estradiol into ovariectomized rats the total free amino acid level in the uterus was estimated by reaction with ninhydrin. The free amino acid content per unit dry weight increased in a linear fashion from about 4 hours to 30 hours after hormone treatment; the increase amounted to 33% of the control value. No increase in free amino acid concentration was apparent at 4 hours, although an increase in dry weight had occurred by this time. It should be pointed out, however, that there was an increase in free amino acids per uterus. During this same period the free amino acid content of the blood did not change perceptibly. Two-dimensional paper chromatograms of uterine amino acids were made for the 4-hour and 24-hour intervals after estrogen and for control uteri. These studies showed an increase in all amino acids 24 hours after estradiol injection, although 2 amino acids failed to meet the test of significance. All but 4 amino acids showed moderate, but not significant, increases for the 4-hour period. Of the 4 amino acids which did not increase at all glycine alone showed a significant depression. As indicated in the discussion there is ample experimental evidence to explain this decrease. It is concluded that estradiol increases the total free amino acid content of the uterus without changing the blood level, and that the increase is accompanied by an alteration in the amino acid pattern of this tissue.

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