Biphasic change in correlation between ovarian lipid peroxides and progestational activity during pseudopregnancy induced in immature rats

We measured ovarian lipid peroxide (LP) levels and plasma progestins, proge sterone (P-4) and 20 alpha-dihydroprogesterone, throughout pseudopregnancy in gonadotropin-primed immature rats. Plasma P-4 fluctuated, with two peaks on days 5 (PSP5) and 8 of pseudopregnancy, and then declined to the basal level by PSP12. Ovarian LP increased from PSP1 to PSP4, decreased temporari ly until PSP8, and then rose gradually until PSP14. From PSP1 through PSP7, ovarian LP was positively correlated with total progestins according to th e Spearman ranked correlation coefficient (r=divided by 0.829, p<0.05). IN contrast, a negative correlation between ovarian LP and plasma P-4 was appa rent (r=-0.816, p<0.05) from PSP8 to PSP14. These results show the biphasic correlation of LP with luteal progestational activity depending on the lut eal stage.