Reduction of maximum exercise capacity in adult male rats with fetal hypothyroidism

Estimation of maximal exercise capacity can be used as a diagnostic test in patients with cardiovascular disorders without clinical symptoms. Deficiency of thyroid hormones during fetal life can puts the cardiovascular system at risk. The aim of this study was to assess maximal exercise capacity in offspring male rats with fetal hypothyroidism (FH).

FH was induced in pregnant Wistar rats by administrating 0.025% 6-propyl-2-thiouracil (PTU) in drinking water throughout pregnancy (from first day of pregnancy till delivery), while pregnant rats in control group used only tap water. Maximum exercise capacity (n = 10) was evaluated by running adult male offspring on the treadmill.

The results showed that heart and body weight were lower in FH group than control group. The maximum exercise capacity in offspring rats with FH was also low (p< 0.05). In addition, these rats significantly lost body weight during exercise (adaptation to treadmill and maximum exercise capacity test) compared to control rats.

These findings suggest that maternal thyroid hormone deficiency can lead to reduced maximum exercise capacity in offspring at adulthood.