GESTATION CONFERS TEMPORARY RESISTANCE TO PEROXIDATION IN THE MATERNAL RAT-BRAIN

Lipid peroxidation, as assessed by the formation of thiobarbituric aci d substances on incubation with ascorbate-Fe2+, NADPH-ADP-Fe3+ and cum ene hydroperoxide in brain homogenate and mitochondria, was significan tly decreased during gestation and restored to respective control leve ls post partum. The decrease observed with the brain homogenate on Day 10 of pregnancy was 42% with ascorbate-Fe2+ and 70% with NADPH-ADP-Fe 3+. This temporary decrease in peroxidation potential seems to be due to lesser availability of substrate in the form of unsaturated fatty a cids besides increase in the cholesterol:phospholipid ratio and glutat hione. Progesterone, the gestational steroid elaborated during pregnan cy, inhibited lipid peroxidation in brain mitochondria in a dose-depen dent manner. The observed temporary decrease in peroxidation potential may be a special adaptation to protect membranes in the brain against oxidant stress during pregnancy.