Malondialdehyde binding of rat cerebral proteins is reduced in experimental hypothyroidism

To determine the effect of thyroid hormones (TH) on cerebral tissue malondi aldehyde (MDA) content and accumulation of MDA-bound proteins, hyperthyroid rats and hypothyroid rats were compared to euthyroid controls. Hyperthyroi dism was induced by daily injection of L-3,5,3'-triiodothyronine (15 ug (10 0 g)(-1)) intraperitoneally daily for 10 days. Hypothyroidism was induced w ith 0.025% methimazole in the drinking water for 4 weeks. Immunoblot analys is of cerebral and plasma proteins was carried out using a specific anti-MD A-protein antiserum. MDA was measured as thiobarbituric acid reactive subst ance. Hypothyroidism was associated with significant reduction in MDA-prote ins of plasma (59.3 +/- 9.5% vs. 99.8 +/- 23.0% of control p < 0.05) and ce rebral tissue (17.6 +/- 19.9% vs. 100.2 +/- 29.0% of control p < 0.001). Hy perthyroidism did not significantly alter MDA-protein distribution. These c hanges did not correlate with cerebral tissue or plasma MDA concentration. It is concluded that hypothyroidism in rats is associated with significant decrease in MDA-bound proteins. This may have some clinical and biological implications. (C) 1999 Elsevier Science B.V. All rights reserved.