Multiple roles of the prostaglandin D2 signaling pathway in reproduction.

Prostaglandins signaling molecules are involved in numerous physiological processes. They are produced by several enzyme-limited reactions upon fatty acids, which are catalyzed by two cyclooxygenases and prostaglandin synthases. In particular, the prostaglandins E-2 (PGE(2)), D-2 (PGD(2)), and F-2 (PGF(2 alpha)) have been shown to be involved in female reproductive mechanisms. Furthermore, widespread expression of lipocalin- and hematopoietic-PGD(2) synthases in the male reproductive tract supports the purported roles of PGD(2) in the development of both embryonic and adult testes, sperm maturation, and spermatogenesis. In this review, we summarize the putative roles of PGD(2) signaling and the roles of both PGD(2) synthases in testicular formation and function. We review the data reporting the involvement of PGD(2) signaling in the differentiation of Sertoli and germ cells of the embryonic testis. Furthermore, we discuss the roles of lipocalin-PGD(2) synthase in steroidogenesis and spermatogenesis, in terms of lipid molecule transport and PGD(2) production. Finally, we discuss the hypothesis that PGD(2) signaling may be affected in certain reproductive diseases, such as infertility, cryptorchidism, and testicular cancer.