QuicKey Pro Rat E3(Estriol) ELISA Kit (E-OSEL-R0004)

This ELISA kit uses the Competitive-ELISA principle. The micro ELISA plate provided in this kit has been pre-coated with Rat E3. Samples (or Standards) and Horseradish Peroxidase (HRP) linked antibody specific for Rat E3 are added to the micro ELISA plate wells. Rat E3 in samples (or standards) competes with a fixed amount of E3 on the solid phase supporter for sites on the HRP linked detection antibody specific to E3. Excess conjugate and unbound sample or standard are washed from the plate. The substrate solution is added to each well. The enzyme-substrate reaction is terminated by the addition of stop solution and the color turns yellow. The optical density (OD) is measured spectrophotometrically at a wavelength of 450±2 nm. The concentration of Rat E3 in the samples is then determined by comparing the OD of the samples to the standard curve.

Estriol is a sex hormone that can be detected in the urine of pregnant women. The effect of estrogen is weaker than that of estrone. Dhea, which is produced in the adrenal glands of the fetus, is hydroxylated by 16α in the liver and aromatized in the placenta to become estriol. As the pregnancy progresses, the amount of excretion in the urine gradually increases, and then drops sharply after delivery. As a palliative sex hormone reagent, it can treat menopause disorders by oral administration. Estriol (E3), the most abundant estrogen in pregnancy is produced predominantly in the placenta from androgen precursors of fetal origin.  The estriol so formed is secreted efficiently into the maternal circulation where it is converted to 4 conjugates--estriol-3-sulfate (E3-3S), estriol-16-glucosiduronate (E3- 16G ), estriol-3-glucosiduronate (E3- 3G ) and estriol-3-sulfate-16-glucosiduronate (E3-SG).  The order of renal clearances is E3- 16G greater than E3- 3G greater than E3-3S approximately E3-SG.  Unconjugated E3 and E3- 3G differ from the other forms of estriol in that their removal from the blood compartment is essentially irreversible.  E3-3S, E3- 16G and E3-SG undergo interconversions during enterohepatic circulation and eventual partial conversion to E3- 3G .  Following delivery of the fetus and placenta, unconjugated E3 is no longer detectable in the maternal serum within 1-2 h, whereas the concentrations of the conjugates decline more slowly, the rates being determined by the rates of renal clearance and enterohepatic interconversions.  E3- 3G levels were dramatically elevated in a case of Group C polycystic kidney disease, providing evidence that this conjugate is indeed an end-product of estriol metabolism.