Protective effect of oestradiol in the coeliac ganglion against ovarian apoptotic mechanism on dioestrus

► A system ex vivo celiac ganglion–SON–ovary and the ovarian incubations were used. ► Oestradiol in the ganglion presented a different response compared the ovary alone. ► Oestradiol in ovarian induces regression of the corpus luteum mediated by system bax/bcl2. ► The steroid through peripherical nervous system has a protective effect against the apoptosis on DII. The aims of this work were to investigate if oestradiol 10−8M 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 (P4) and oestradiol (E2) 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 P4 release was measured in both experimental schemes, and ovarian P4 and E2 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. E2 added in the coeliac ganglion caused an increase in the ovarian release of the P4, E2 and 3β-HSD, while in the ovary incubation alone it decreased P4 and 3β-HSD but increased and 20α-HSD and bax/bcl-2 ratio. It is concluded that through a direct effect on the ovary, E2 promotes luteal regression in DII rats, but the addition of E2 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.