The aims of this work were to investigate if oestradiol 10 −8 M in the incubation media of either the ovary alone (OV) or the ganglion compartment of an ex vivo coeliac ganglion–superior ovarian nerve–ovary system (a) modifies the release of ovarian progesterone (P 4 ) and oestradiol (E 2 ) on dioestrus II, and (b) modifies the ovarian gene expression of 3β-HSD and 20α-HSD enzymes and markers of apoptosis. The concentration of ovarian P 4 release was measured in both experimental schemes, and ovarian P 4 and E 2 in the ex vivo system by RIA at different times. The expression of 3β-hydroxysteroid dehydrogenase, 20α-hydroxysteroid dehydrogenase and antiapoptotic bcl-2 and proapoptotic bax by RT-PCR were determined. E 2 added in the coeliac ganglion caused an increase in the ovarian release of the P 4 , E 2 and 3β-HSD, while in the ovary incubation alone it decreased P 4 and 3β-HSD but increased and 20α-HSD and bax/bcl-2 ratio. It is concluded that through a direct effect on the ovary, E 2 promotes luteal regression in DII rats, but the addition of E 2 in the coeliac ganglion does not have the same effect. The peripheral nervous system, through the superior ovarian nerve, has a protective effect against the apoptotic mechanism on DII.