Acute Dose-Related Differential Effects of Methylphenidate on Murine Cystometric Parameters

PURPOSE: Methylphenidate is the most widely used central nervous system stimulant in patients with attention deficit hyperactivity disorder. However, few studies have assessed its effects on voiding. Various doses of methylphenidate were investigated for their effects on cystometric parameters in conscious mice. METHODS: Ten male C57BL/6 mice, weighing between 20 and 23 g, were used in this study. To compare the acute drug responses before and after the oral medication was administered in the awake condition, we injected the solution through a catheter inserted into the stomach. Methylphenidate (1.25, 2.5, and 5 mg/kg) in an injection volume of 0.05 mL was administered. RESULTS: Four mice that received high doses of methylphenidate (2.5 and 5 mg/kg) showed no voiding contraction, with urine leakage. Six mice that received a low dose of methylphenidate (1.25 mg/kg) showed typical micturition cycles before and after administration. The micturition pressure decreased and bladder capacity increased without an increased residual volume after administration. CONCLUSIONS: Methylphenidate has differential, dose-dependent effects on the function of the lower urinary tract, due to the dependent relationship between the brain and lower urinary tract. Especially at higher doses, this drug may interfere with normal micturition. Therefore, more detailed clinical or experimental studies are warranted in the future.