Identification of maturation-inducing steroid in sturgeons via comprehensive analyses of steroids produced during oocyte maturation.

Although 17α, 20β-dihydroxy-4-pregnen-3-one (DHP) and 17α, 20β, 21-trihydroxy-4-pregnen-3-one (20β-S) have been identified as maturation-inducing steroids (MIS) in several teleosts, to date, no MISs have been identified in sturgeons. As it remains possible that an unidentified steroid is an MIS in sturgeons, this study aimed to identify a sturgeon MIS via comprehensive analyses and maturation-inducing (MI) assay of C21 steroids. In vivo and in vitro comprehensive analyses of C21 steroids revealed that serum DHP concentrations were rapidly elevated in the oocyte maturation phase and the DHP production level was notably high among C21 steroids.