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.