The Impact of Levothyroxine and Testosterone Administration on Bladder Contractility in the Rat Model of Propylthiouracil-Induced Hypothyroidism.

Objective: To investigate the effects of testosterone (T) treatment, with or without levothyroxine, the most widely used and least effective medication for managing hypothyroidism, on the functional and histological changes in propylthiouracil (PTU)- induced hypothyroid rat bladders.

Methods: Male rats (n=35) were split into control, hypothyroid, hypothyroid rats treated with levothyroxine (20 µg/kg/day, oral, 2-weeks), hypothyroid rats treated with Sustanon (10 mg/kg,iIM, once/week, 2-weeks), and hypothyroid rats treated with combined treatment groups. Hypothyroidism was induced by PTU (0.05% in drinking water, 6 weeks). The serum concentration of triiodothyronine (T3), thyroxine (T4), total T, and the detrusor muscle's contractile responses were determined. A morphological study was conducted using Masson trichrome staining.

Results: Triiodothyronine, T4, and T levels were considerably reduced in rats with hypothyroidism; however, these hormones were restored by levothyroxine and Sustanon. Compared to controls, the combination therapy improved the ratio of smooth muscle to collagen and the contractile responses to carbachol, electrical field stimulation, and adenosine triphosphate in the hypothyroid bladder.

Conclusion: The authors' research suggests that hypothyroidism may affect the contractility and morphology of the bladder. In males with hypothyroidism and urogenital system dysfunction, combination therapy with thyroid hormones and T has a major impact on repairing detrusor smooth muscle contractility and bladder histomorphology.