Expression of aldo-keto reductase 1C23 in the equine corpus luteum in different luteal phases.
Regression of the corpus luteum (CL) is characterized by a decay in progesterone (P4) production (functional luteolysis) and disappearance of luteal tissues (structural luteolysis). In mares, structural luteolysis is thought to be caused by apoptosis of luteal cells, but functional luteolysis is poorly understood. 20α-hydroxysteroid dehydrogenase (20α-HSD) catabolizes P4 into its biologically inactive form, 20α-hydroxyprogesterone (20α-OHP). In mares, aldo-keto reductase (AKR) 1C23, which is a member of the AKR superfamily, has 20α-HSD activity. To clarify whether AKR1C23 is associated with functional luteolysis in mares, we investigated the expression of AKR1C23 in the CL in different luteal phases. The luteal P4 concentration and levels of 3β-hydroxysteroid dehydrogenase (3β-HSD) mRNA were higher in the mid luteal phase than in the late and regressed luteal phases (P<0.05), but the level of 3β-HSD protein was higher in the late luteal phase than in the regressed luteal phase (P<0.05). The luteal 20α-OHP concentration and the level of AKR1C23 mRNA were higher in the late luteal phase than in the early and mid luteal phases (P<0.05), and the level of AKR1C23 protein was also highest in the late luteal phase. Taken together, these findings suggest that metabolism of P4 by AKR1C23 is one of the processes contributing to functional luteolysis in mares.
Laboratory of Reproductive Physiology, Graduate School of Environmental and Life Science, Okayama University, Okayama 700-8530, Japan.
Keisuke
K
Kozai
Takuo
T
Hojo
Shota
S
Tokuyama
Anna Z
AZ
Szóstek
Masashi
M
Takahashi
Miki
M
Sakatani
Yasuo
Y
Nambo
Dariusz J
DJ
Skarzynski
Kiyoshi
K
Okuda
D004092:20-alpha-Dihydroprogesterone / Q000096:biosynthesis / Q000235:genetics; D015096:3-Hydroxysteroid Dehydrogenases / Q000096:biosynthesis / Q000235:genetics; D000449:Aldehyde Reductase / Q000096:biosynthesis* / Q000235:genetics; D000074408:Aldo-Keto Reductases; D000818:Animals; D015153:Blotting, Western; D003338:Corpus Luteum / Q000201:enzymology*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D006736:Horses / Q000378:metabolism*; D008183:Luteal Phase / Q000378:metabolism*; D003341:Luteolysis / Q000502:physiology*; D011374:Progesterone / Q000096:biosynthesis / Q000235:genetics; D012313:RNA / Q000737:chemistry / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary
D004092:20-alpha-Dihydroprogesterone; D011374:Progesterone; D012313:RNA; D015096:3-Hydroxysteroid Dehydrogenases; D000074408:Aldo-Keto Reductases; D000449:Aldehyde Reductase