ANTIOXIDANT CAPACITY IS CORRELATED WITH STEROIDOGENIC STATUS OF THE CORPUS-LUTEUM DURING THE BOVINE ESTROUS-CYCLE

The reactions of steroid hormone biosynthesis: are accompanied by form ation of oxygen radicals. We determined the levels of some antioxidant s and antioxidative enzymes at different developmental stages of bovin e corpora lutea to examine their correlation with steroidogenic status . Plasma progesterone concentrations of estrous cycle synchronized cow s increased until day 16, and then decreased rapidly during luteal reg ression. The levels of steroidogenic cytochrome P450scc and adrenodoxi n paralleled the changes in plasma progesterone. Among the antioxidati ve enzymes examined, the SOD and catalase activities showed patterns m ost similar to plasma progesterone. Catalase and SOD activities increa sed 6-8 fold from day 6 to 16 of the estrous cycle and then decreased during the luteal repression. Ascorbate and beta-carotene showed low b ut significant correlation with P450scc and plasma progesterone levels . The profiles of two lipophilic antioxidants in corpora lutea were ve ry different. beta-carotene concentration increased by approximately 6 fold from day 6 to 16, and decreased in regressive tissue. alpha-toco pherol showed a 3 fold increase between days 6 and 9 followed by a rap id decrease. Thus, at the peak of steroidogenesis at mid-luteal phase alpha-tocopherol levels decreased, but beta-carotene levels increased. The correlation between the levels of some antioxidant enzymes and co mpounds with progesterone levels indicates that antioxidative mechanis ms are activated to cope with steroidogenesis dependent oxyradical for mation in the bovine corpus luteum. (C) 1998 Elsevier Science B.V.