INFLUENCE OF HYPOTHYROIDISM ON LIPID METABOLISM IN THE HEART OF VIRGIN RAT

CARMONA Y; MARRA C; OLIVEROS L; GIMENEZ MS

SAN JUAN

Congreso; Second Joint Meeting of the Biology Societies from Argentina. - ARGENTINA.; 2011

Sociedades de Biología de la Republica Argentina

Thyroid state influences cell and plasma lipid composition. The aim of this work was to determine the effects of hypothyroidism on lipid metabolism in the heart of female virgin Wistar rats, weighing 150-180g. Hypothyroid state was induced by administration of  6-n-propyl 2-thiouracil (100 mg/L) in the drinking water, for 30 days. Age-matched euthyroid rats were used as controls. Serum lipids were measured by Wiener kits and heart lipids by spectrophotometric assays after lipid extraction  (Folch method) and separation of the different lipid fractions (thin-layer chromatography). mRNA expressions of peroxisome proliferator-activated receptor-α (PPARα) and sterol regulatory element binding protein 1c (SREBP-1c) were determined by RT-PCR, using  β-actin as internal control. Heart fatty acid composition was determined by gas-liquid chromatography. Hypothyroid state induced an increase of serum cholesterol and LDLc, a decrease of serum and heart triglycerides (TG) (p<0.01), and an increase of the heart fatty acid unsaturation index (UI). Heart mRNA levels of PPARα was decreased (p<0.01), without change in SREBP-1c, in relation to control. Hypothyroid state alters serum and heart lipids content, and decreases the expression of PPARα, which is involved in the regulation of heart energetic balance. In addition, the high UI suggests a low protection against fatty acid oxidation in heart.