Microarray analysis of hyperthyroid and euthyroid rat sertoli cells.

Thyroid hormone is known to play an important role in the regulation of prepubertal rat testes development and function with specific influence on the differentiation of Sertoli cells. Hypothyroidism results in continued proliferation of Sertoli cells beyond their normal period of cell proliferation arrest, whereas hyperthyroidism causes premature cell cycle arrest. In order to explore the in vivo mechanism of thyroid hormone action on proliferation and differentiation of Sertoli cell, global gene profiling was carried out using the hyperthyroid rat model system. Hyperthyroidism in rats was established by injecting T3 to pups (i.p. 100 g/ kg bw/ day) immediately after birth. The euthyroidic and hyperthyroidic rats were sacrificed on 13th day. A significant decrease in BrdU incorporation by the hyperthyroidic rat Sertoli cell indicated arrest of proliferation. Total RNA was isolated from both the group of Sertoli cells and microarray analysis was carried out using Rat oligo v 3.0 slides obtained from University of Cincinnati Medical Centre, Cincinnati, Ohio. Image Analysis was performed using Genepix Pro software. The results revealed upregulation of markers which are specific for mature Sertoli cells. It was observed that there was more that three-fold increase in the expression of clusterin, eppin, androgen binding protein, cystatin TE, cystatin C, and estradiol 17- dehydrogenase and down regulation of early growth response protein 2, collagen 1 (XII) and plaminogen activator inhibitor 1in Sertoli cells following hyperthyroidism. RTPCR analysis was carried out to confirm the regulation of a few markers. The results suggest that following neonatal hyperthyroidism there is a premature differentiation of the Sertoli cells and the cells behave as mature cells by upregulation of the functional markers. (Supported by CONRAD and MELLON foundation, USA, CSIR, ICMR, DST and DBT Govt. of India and CSIR Emeritus Scientist Fellowship.