An involvement of reactive oxygen species in CL regression has been re
ported. We have shown that a decrease in serum progesterone concentrat
ions coincides with a decrease in superoxide dismutase (SOD) activitie
s and an increase in lipid peroxide levels in the CL after Day 15 of p
regnancy. Recently it has been found that ischemia-reperfusion stimula
tes reactive oxygen species production and causes tissue damage in var
ious organs. We therefore tested the effect of ischemia-reperfusion in
the ovary on CL function in pregnant rats. On Day 15 of pregnancy, af
ter clamping of the bilateral ovarian vessels for 30 min, the ovaries
were reperfused for 90 min by declamping. The ischemia-reperfusion dec
reased serum progesterone concentration and SOD activity in the CL and
increased lipid peroxide in the CL 90 min after reperfusion. The effe
cts of ischemia-reperfusion, including the decrease in serum progester
one concentrations, were completely blocked by simultaneous injection
of SOD and catalase, but not by indomethacin administration. The prese
nt study shows that CL function was inhibited by reactive oxygen speci
es produced by ischemia-reperfusion in the ovary and that the effect w
as not mediated through prostaglandins.