MP07-09: Treatment with levothyroxine and testosterone affect bladder contractility and histomorphology differently in the rat model of propylthiouracil-induced hypothyroidism
Introduction: Urinary dysfunctions are related to thyroid problems and, particularly, to hypothyroidism. The mechanisms involved remain to be addressed. Current data are highly relevant as micturition requires somatovisceral reflexes involving bladder, urethra, and pelvic floor muscles. A limited number of studies have reported the roles of thyroid hormones and testosterone (T) on bladder histology and function. To fill this gap, the current study was aimed to determine the effect of levothyroxine, which is the most common and least effective drug for controlling hypothyroidism, with/without testosterone treatment on histological and functional alteration in propylthiouracil (PTU)-induced hypothyroid rat bladder.
Methods: Adult male Wistar rats (n = 35) were divided into five groups; 1) control rats, 2) hypothyroid rats, 3) hypothyroid rats treated with levothyroxine (20 mg/kg/day, oral, 2-wk), 4) hypothyroid rats treated with Sustanon (a mixture of 4 types of T: propionate, phenylpropionate, isocaproate, decanoate, 10 mg/kg, I.M., once/week, 2-wk) and 5) hypothyroid rats treated with combined therapy. Hypothyroidism was induced by PTU (0.05% in drinking water, 6wk). Serum levels of total T, triiodothyronine (T3), and thyroxine (T4) were measured. The contractile responses of detrusor muscle were obtained from in vitro studies. Hematoxylin-eosin and Masson trichrome staining were performed for morphological analysis.
Results: The rat model of hypothyroidism showed a significant decline in serum levels of total T, T3, and T4, which was normalized by combined treatment with levothyroxine and Sustanon. Bladder weight was not significantly different among groups. Contractile responses to carbachol, electrical field stimulation (EFS), and ATP in bladder tissues from hypothyroid rats were lower than in controls (p < 0.01), which was increased after the combined treatment. The combination treatment with levothyroxine and Sustanon modulated a reduced ratio of smooth muscle to collagen in rats with hypothyroidism.
Conclusions: Current study reveals that bladder morphology and contractility may be deteriorated by hypothyroidism. Combined treatment with thyroid hormones and T has a significant role to restore both contractility and histomorphology of bladder tissue in hypothyroid men with urogenital system dysfunction. Our findings would be valuable to gain insight into the role that thyroid hormones play in male micturition.
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