The effect of swimming exercise on thyroid function, spatial memory and anxiety in normal and propylthiouracil-induced hypothyroidism in Wistar rats

Introduction: Swimming exercises improve various nerve growth factors and angiogenesis that encouraged the researchers to investigate the effect of swimming exercises on thyroid function (cyclic adenosine monophosphate [cAMP] and dual oxidase 2 [DUOX2] in free T4 [FT4] secretion), spatial memory, behavior and anxiety on normal Wistar pups and those given with propylthiouracil (PTU). Methods: The subjects of this research were normal Wistar pups and those given 25 ppm PTU from the 1st week until the 12th week of age. Swimming activity was started in 4-weekold pups after acclimatization for 1 week. Swimming exercises were conducted with a load of 1–2% body weight and 30min duration per day, 5 times a week for 8 weeks. The levels of FT4 serum, cAMP and DUOX2 of the thyroid gland homogenate were measured using enzyme-linked immunosorbent assay. The rats’ ability to maintain spatial memory was measured using the Morris water maze and anxiety using the open field maze. Results: The FT4 levels significantly decreased after the administration of 25 ppm PTU for 3 weeks and it was much more decreased after 12 weeks administration. The administration of 25 ppm PTU for 12 weeks reduced the cAMP levels, increased DUOX2 and reduced the spatial memory skills and exploration behavior of rats. Swimming exercise increased and normalized these parameters. Conclusion: Swimming exercises for 8 weeks improve thyroid function, learning ability and spatial memory of normal and PTU-induced hypothyroid Wistar rats.