ABSTRACT
OBJECTIVE: To investigate the effect of intrathecal galanin on the micturition reflex in rats. METHODS: Continuous cystometrograms (0.04 mL/min infusion rate) were performed in female Sprague-Dawley rats (225-248 g) under urethane anesthesia. After stable micturition cycles were established, galanin was administered intrathecally to evaluate changes in bladder activity. Then, to examine the involvement of opioid systems in the galanin effects, galanin was administered intrathecally when the first bladder contraction was observed after intrathecal administration of naloxone, an opioid receptor antagonist. RESULTS: Intrathecal administration of galanin (1-10 µg) increased intercontraction intervals in a dose-dependent fashion. Intrathecal administration of galanin (1-10 µg) also increased pressure threshold in a dose-dependent fashion. These inhibitory effects of galanin (10 µg) were partially antagonized by intrathecal administration of naloxone (10 µg). CONCLUSION: These results indicate that in urethane-anesthetized rats, galanin delays the onset of micturition through activation of the opioid mechanism, suggesting the inhibitory role of galanin system in the control of the micturition reflex.