Progesterone metabolism in vitro in the decapod crustacean, Penaeus monodon

Thin-layer chromatography (TLC) and reversed-phase high-performance liquid chromatography (RP-HPLC) with on-line detection of radioactive steroids were applied to identify metabolites of [4-14C]progesterone incubated in vitro with prawn ovary. There was extensive metabolism of progesterone by stage II (vitellogenic) ovary of Penaeus monodon. The most abundant metabolites were 5 alpha-pregnane derivatives together with two minor metabolites, 20 alpha-hydroxypregn-4-en-3-one and 1,4-pregnadiene-3,20-dione. In contrast, a much lower level of progesterone metabolism was observed in stage 0 (immature) ovary of this species. The hepatopancreas, gill, and abdominal muscle of P. monodon all metabolised [4-14C]progesterone to varying degrees, generating materials similar to those produced by the ovary. A comparative study of progesterone metabolism in stage II ovary of Nephrops norvegicus indicated that one metabolite, 20 alpha-hydroxypregn-4-en-3-one, was produced.