| Purpose: To investigate the effect of the 5-HT2 A receptor in the Onuf's nucleus of the sacral cord on external urethral sphincter activity in female rats.Materials and Methods: Female Sprague-Dawley? rats were used.Cystometrograms were taken under urethane anesthesia in all rats. The selective5-HT2 A antagonist ketanserin(0.01-0.1mg/kg) were given by intrathecal catheter in the spinal L6-S1 segment. Dose-response curves for ketanserin were followed by DOI(0.1mg/kg) test. In control rats, normal saline were given insteadly. All rats were intravascularly perfused with 4% paraformaldehyde after cystometry. The L6-S1 Spinal cords were removed and pathological sections and immunohistochemical staining were made to observe the distribution of 5-HT2 Areceptors in the spinal motor neuron.Results: One-way ANOVA followed by LSD test were used for the effect sizes comparisons within and between groups. Compared to controls, ketanserin induced a significant dose-dependent decrease of the high-frequency oscillation activity, evident as a decrease in the number of small oscillations per voiding. However, micturition volume, post-void residual volume and voiding efficiency showed no significant difference. Effects of ketanserin were partially or completely reversed by DOI. In the L6 segment of the female rats, immumohistochemical staining displayed the different distribution of 5-HT2 A receptor immunohistochemical labelings were found in theretrodorsolateral nucleus, ventromedial nucleus, Onuf's nucleus including dorsal lateral nucleus in the spinal anterior horn.Conclusion: Ketanserin can specially be bound up with 5-HT2 A receptor in the Onuf's nucleus of the sacral cord and inhibit EUS activity, of which can also be modulated by Supraspinal or Spinal projection of serotonergic pathways and the quantity of 5-HT2 Areceptors, leading to no significant effects on micturition. |
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