Physiol. Res. 53: 69-75, 2004

Triiodothyronine Deiodinating Activity in Brown Adipose Tissue after Short Cold Stimulation Test in Trained and Untrained Rats


1Second University of Naples, Faculty of Medicine and Surgery, Department of Experimental Medicine, Human Physiology Section, Napoli, Italy, 2Department of Trauma and Orthopaedic Surgery, Keele University School of Medicine, North Staffordshire Hospital, Thornburrow Drive, Hartshill, Stoke on Trent, Staffordshire, United Kingdom

Received February 3, 2003
Accepted March 24, 2003

Interscapular brown adipose tissue (IBAT) activity is controlled by sympathetic nervous system, and factors that influence thermogenesis appear to be centrally connected to the sympathetic outflow to IBAT. Cold exposure produces a rise in BAT temperature, which is associated with an increased thyroid activity, elevated serum levels of 3,5,3-triiodothyronine (T3), and an increased rate of T3 production. This study evaluated the effect of swimming training on 5-triiodothyronine deiodinase (5-D) activity in IBAT under normal environmental conditions and after short (30 min) cold exposure (TST stimulation test). 5-D activity is lower in trained rats at basal condition, and TST increases 5-D in IBAT of both untrained and trained rats. However, this increase is lower in trained rats. Training reduces the deiodinating activity in normal environmental conditions as well as after short cold exposure. Probably, other compensatory mechanisms of heat production are active in trained rodents.

Key words
Deiodinase activity Thyroid hormone Training Brown adipose tissue Thermogenesis

2004 by the Institute of Physiology, Czech Academy of Sciences