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Objectives: To examine the effect of intrathecal (i.t.) serotonin (5‐hydroxytryptamine) 5‐HT7 agonist administration on voiding function in the urethane‐anesthetised rat, and the change in 5‐HT7 receptor (5‐HT7R) expression in the lumbosacral cord Onuf's nucleus after spinal cord injury (SCI). Materials and methods: In all, 32 female Sprague–Dawley (SD) rats were equally divided into a spinally intact (SI) group and SCI group (n = 16 each). At 8 weeks after transection, half of the rats underwent continuous cystometry under urethane anaesthesia, and the 5‐HT7R‐selective agonist LP44 was given (i.t.). The remaining rats were used for pseudorabies (PRV) retrograde tracing, immunofluorescence, and Western Blot. Results: LP44 administered i.t. had no effect in the SI rats. In SCI rats, LP44 (1–30 μg/kg) induced significant dose‐dependent increases in micturition volume, voiding efficiency, number of high‐frequency oscillations per micturition; and decreases in residual volume, bladder capacity, peak bladder pressure, threshold pressure and non‐voiding contractions. The 5‐HT7R antagonist, SB‐269970 (10 μg/kg), partially reversed LP44‐induced changes. Using PRV retrograde tracing and immunofluorescence, 5‐HT7Rs were found in the L6–S1 spinal cord Onuf's nucleus in both SI and SCI rats, but the expression was significantly greater in the SCI rats. Western blot showed significantly more 5‐HT7Rs in the ventral L6–S1 spinal cord in SCI rats. Conclusion: A 5‐HT7R agonist, given i.t., improved voiding efficiency in urethane‐anesthetised SCI rats, and the 5‐HT7R was significantly up‐regulated in the lumbosacral cord Onuf's nucleus. If valid for humans, these findings suggest that the 5‐HT7R could be a target for therapeutic interventions. [ABSTRACT FROM AUTHOR]

Objectives: To investigate whether the voiding dysfunction caused by spinal cord injury (SCI) in rats can be improved by i.v. administration of the serotonin (5‐HT)2A/2C receptor agonist 2,5‐dimethoxy‐4‐iodophenyl‐2‐aminopropanehydrochloride (DOI), and to discuss whether the mechanism can be ascribed to 5‐HT2A and 5‐HT 2C receptor upregulation in lumbosacral cord motoneurons. Materials and Methods: Female Sprague–Dawley rats were divided into two groups (SCI group vs normal control [NC] group). Under urethane anaesthesia, cystometry was performed to examine the variation in urodynamic variables before and after successive intrathecal (i.t.) administration of various doses of DOI into the lumbosacral cord. Changes in 5‐HT2A and ‐2C receptors in the lumbosacral cord were also investigated using immunohistochemical staining and Western blot analysis. Results: Compared with NC rats, the SCI rats had higher bladder capacity and post‐void residual urine volume, and lower voiding efficiency. After SCI, DOI improved voiding efficiency, probably via external urethral sphincter (EUS) activity. Immunohistochemical staining and Western blot analysis showed that 5‐HT2A and ‐2C receptors were upregulated in lumbosacral cord motoneurons. Conclusion: In rats with SCI, DOI can improve voiding efficiency; this may be attributable to 5‐HT2A and ‐2C receptor upregulation in lumbosacral cord motoneurons controlling EUS activity. [ABSTRACT FROM AUTHOR]

Objectives To examine the effects of the serotonin (5- HT) 2A/2C receptor agonist (2,5-dimethoxy-4-idophenyl)-2-aminopropane hydrochloride ( DOI) on micturition in rats with diabetes mellitus ( DM). Methods Female Sprague- Dawley rats ( n = 16) were divided into two groups: rats with Type 1 DM and age-matched control rats. DM was induced by i.p. injection of streptozotocin (65 mg/kg) and detailed cystometrogram ( CMG) studies were performed 8 weeks post-injection in all rats under urethane anaesthesia. The selective 5- HT2A antagonist ketanserin was administered after each DOI dose-response curve was plotted. All drugs were administered i.v. Results Compared with controls, comprehensive urodynamic studies showed that DM rats had a higher bladder capacity and post-void residual urine volume ( PVR), and a markedly lower voiding efficiency. In DM rats, DOI (0.01-0.3 mg/kg) induced significant dose-dependent increases in micturition volume and reductions in PVR, resulting in greater voiding efficiency. CMG measurements showed a dose-dependent increase in high-frequency oscillation ( HFO) activity, evidenced by an increased duration of HFOs per voiding. This correlated with the improved voiding efficiency. Ketanserin (0.1 mg/kg) partially or completely reversed the DOI-induced changes. Conclusions The HFOs observed in the present study seem to correlate with external urethral sphincter bursting activity during voiding. Bladder voiding efficiency was reduced in DM rats. The 5- HT2A receptor agonist can enhance HFO activity and improves voiding efficiency, and so may represent a new strategy to improve voiding efficiency after DM in experimental studies. [ABSTRACT FROM AUTHOR]

Highlights • High frequency oscillation of intravesical pressure is related to the external urethral sphincter burst activity. • The distribution of 5-HT2A receptors was significant denser than that of 5-HT2C receptors in lumbosacral cord motoneurons. • ketanserin has effect on micturition via the 5-HT2A receptors in lumbosacral cord motoneurons. Abstract Objectives This study aimed to investigate the effects of ketanserin on micturition mediated via the 5-HT 2A receptor in the motoneuron nucleus of the Lumbosacral cord, as reflected in high frequency oscillations (HFOs) of intravesical pressure and the external urethral sphincter electromyogram (EUS-EMG) in anesthetized male rats. Methods： Male Sprague-Dawley rats were used. Cystometry and EUS-EMG were performed in all rats under urethane anesthesia to examine the variations after successive intrathecal (i.t.) administration of various doses of ketanserin into the lumbosacral cord. Immunofluorescence staining and Western blotting were made to observe the distribution of 5-HT2 A and −2C receptors in the lumbosacral cord motor neurons. Results Compared to the controls, ketanserin-treated rats showed a declined trend of dose-dependent manner in the HFOs, in accordance with the variation of EUS-EMG, while decreased micturition volume, voiding efficiency, and increased post-void residual volume was only observed at the dose of 0.1 mg/kg. The effects of ketanserin on the HFO and EUS-EMG activity were partially or completely reversed by the 5-HT 2A/2C receptor agonist, DOI. Meanwhile, immunofluorescence staining and Western blot analysis showed that immunoreactivity of 5-HT 2A receptor was higher than that of 5-HT 2C, labeling in the lumbosacral cord motoneurons. Conclusions The intrathecally administrated 5-HT 2A receptor antagonist ketanserin can weaken the EUS bursting activity, decrease HFOs, and reduce voiding efficiency as dose dependently. The effects of ketanserin on micturition may be mainly mediated via the 5-HT 2A receptors in the motoneuron nucleus of the lumbosacral cord. [ABSTRACT FROM AUTHOR]