Brain carbon monoxide can suppress the rat micturition reflex through brain γ-aminobutyric acid receptors

Abstract

Objectives: To investigate roles of brain carbon monoxide (CO), an endogenous gasotransmitter, in regulation of the rat micturition reflex.

Methods: In urethane-anesthetized (0.8 g/kg, ip) male rats, evaluation of urodynamic parameters was started 1 h before intracerebroventricular administration of CORM-3 (CO donor) or ZnPP (non-selective inhibitor of heme oxygenase, a CO producing enzyme) and continued for 2 h after the administration. We also investigated effects of centrally pretreated SR95531 (GABA_A receptor antagonist) or SCH50911 (GABA_B receptor antagonist) on the CORM-3-induced response.

Results: CORM-3 significantly prolonged intercontraction intervals (ICIs) without changing maximal voiding pressure (MVP), while ZnPP significantly shortened ICI and reduced single-voided volume and bladder capacity without affecting MVP, post-voided residual volume, or voiding efficiency. The ZnPP-induced ICI shortening was reversed by CORM-3. The CORM-3-induced ICI prolongation was significantly attenuated by centrally pretreated SR95531 or SCH50911, respectively.

Conclusions: Brain CO can suppress the rat micturition reflex through brain γ-aminobutyric acid (GABA) receptors.

Keywords: GABAA receptor; GABAB receptor; brain; carbon monoxide; micturition reflex.