Regulation of Gene Expression with Thyroid Hormone in Rats with Myocardial Infarction

Thyroid hormone (TH) improves cardiac performance after myocardial infarction (MI); however, the molecular basis is unknown. Methods MI was produced by ligation of the LAD in female SD rats. Rats were divided into the following groups: (1) Sham MI, (2) MI, and (3) MI+T4 treatment (T4 pellet 3.3mg, 60 days release, implanted subcutaneously immediately following MI). Four weeks after surgery, total RNA was isolated from left ventricular non‐infarcted areas for Microarray Analysis using the Illumina RatRef‐12 Expression BeadChip Platform. Results Signals were detected in 13,188 genes (out of 22,523), of which 154 gene expressions were decreased and 200 gene expressions were increased in MI rats compared with Sham MI rats (False Discovery Rate (FDR) < 0.05). Compared to MI rats, T4 treatment decreased expression of 27 genes and increased expression of 28 genes, including mitochondrial, metabolic, vascular development, extracellular matrix and cytoskeleton genes (FDR < 0.05). In particular, 6 genes down‐regulated by MI and 12 genes up‐regulated by MI were normalized by T4 treatment (Table 1). Conclusions These results suggest that altered expression of genes for cardiac metabolism, vascular development, extracellular matrix and cytoskeleton may be involved in the beneficial effects of thyroid hormone treatment of MI in rats.