Abstract

Thyroid hormones (THs), T3 and T4, play an essential role in the development and metabolism of many tissues and organs, and have profound metabolic effects in adult life. Thyroid hormone receptors (TRs) seem to be ubiquitous, but, to our knowledge, their presence in tenocytes has not been investigated. We therefore evaluated the expression pattern of TRs isoforms in three groups of patients: one with rotator cuff tendons tears and with thyroid diseases, one with rotator cuff tendons tears without thyroid diseases, and one with healthy rotator cuff tendons and no thyroid disease. In addition, we evaluated the action of THs on growth and apoptosis of primary tenocyte cultures. The α/β nuclear receptor isoforms are present in healthy and pathologic rotator cuff tendons. THs enhance the growth and counteract apoptosis in primary tenocyte cultures in a dose and time dependent manner.