The oviduct produces erythropoietin in an estrogen- and oxygen-dependent manner.

Previously, we showed that erythropoietin (Epo) is produced in the mouse uterus, where Epo is indispensable for estrogen (E(2))-dependent angiogenesis. Expression of uterine Epo mRNA is stimulated by E(2) and hypoxia. The hypoxic induction requires the presence of E(2). In the present study, we examined other female reproductive organs in the mouse with respect to Epo mRNA expression and its stimuli (E(2) and hypoxia)-induced changes. Although Epo mRNA expression was seen in the ovary and oviduct, the E(2)-induced stimulation of Epo mRNA was found only in the oviduct. The E(2)-induced stimulation in the oviduct was transient and rapidly downregulated. Epo mRNA expression in the oviduct was hypoxia inducible, in both the presence and the absence of E(2). E(2)-dependent production of Epo and its mRNA expression were also found by use of cultured oviducts. The E(2) action is probably mediated through the E(2) receptor, and de novo protein synthesis is not required for E(2) induction of Epo mRNA. In the oviduct, the ampulla and isthmus regions produce Epo.