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Changes in maternal pregnane concentrations in mares with experimentally-induced, ascending placentitis
Michelle A A Wynn1, Barry A Ball1, John May2
1Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, 40546, USA.
Theriogenology
|September 29, 2018
Summary
In mares with chronic placentitis, progesterone metabolites like 20α5P and βα-diol increased significantly before abortion. Acute placentitis led to decreased levels of these key pregnanes, indicating placental compromise.
Area of Science:
- Reproductive endocrinology
- Equine medicine
- Steroid metabolism
Background:
- Ascending placentitis is a common cause of abortion in mares.
- Progesterone and its metabolites play crucial roles in maintaining pregnancy.
- Accurate monitoring of steroid profiles can aid in understanding pregnancy complications.
Purpose of the Study:
- To compare plasma pregnane concentrations in mares with experimentally induced placentitis versus controls.
- To investigate the changes in progesterone (P4) and its metabolites during acute and chronic placentitis.
- To correlate pregnane profiles with pregnancy outcomes in mares.
Main Methods:
- Experimentally induced ascending placentitis in mares using Streptococcus equi spp. zooepidemicus.
- Plasma samples collected pre-abortion in placentitis mares and matched controls.
- Quantification of P4, 5α-dihydroprogesterone (DHP), allopregnanolone, 3β5P, 20α5P, βα-diol, and ββ-diol using LC-MS/MS.
- Measurement of immunoreactive P4 (ir-P4) by immunoassay.
Main Results:
- In chronic placentitis, DHP and its metabolites (allopregnanolone, 3β5P, 20α5P, βα-diol) increased 2-8 days prior to abortion.
- 20α5P and βα-diol showed the largest increase (3-4×) in chronic placentitis mares.
- In acute placentitis, DHP and its metabolites decreased significantly 0-3 days before abortion.
- LC-MS/MS measured P4 remained low in controls and did not significantly increase in chronic placentitis mares.
- ir-P4 increased 2 days prior to abortion in chronic placentitis but not in acute cases.
Conclusions:
- Elevated pregnane metabolites in chronic placentitis suggest placental and fetal stress/adrenal activation.
- Decreased pregnane metabolites in acute placentitis indicate severe fetal or placental compromise.
- LC-MS/MS provides a more accurate measure of P4 than immunoassay in this context.
- Pregnane profiling offers insights into the pathophysiology of placentitis and pregnancy risk.
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