Immunohistochemical characterization of pelvic neurons projecting to the bladder in rats with the artificial somatic-autonomic reflex arc

Abstract

Objective Retrograde-tracing and immunohistochemical techniques were used in combination to investigate the types of putative transmitters in pelvic ganglia neurons projecting to the bladder of rats with the artificial somatic-autonomic reflex arc. Methods The artificial somatic-autonomic reflex arc was established in 8 rats by end-to-end microanastomosis of the proximal stump of the left L4 ventral root to the distal stump of L6 ventral root. The major pelvic ganglia (MPG) neurons innervating the urinary bladder were labeled by retrograde axonal tracing methods with the use of horseradish peroxidase (HRP) injected into the bladder wall and identified with TMB-HRP reaction. Then immunohistochemical (ChAT, TH, VIP, SP) and histochemical methods (NADPH-diaphorase activity and nitric oxide synthase immunoreac-tivity) were used to identify the neurotransmitters of HRP-labeled neurons projecting to the bladder. Results HRP-labeled neurons with spherical or oval shape mainly distributed in the MPG. The HRP-labeled neurons were positive for ChAT (112/279, 40. 1%), TH (50/245,20.4%), VIP(25/233, 10.7%), NOS ( 15/230, 6. 5% ) or SP (8/242, 3. 3% ) respectively. Conclusion These results suggest that ace-tylcholine and adrenaline are the predominant neurotransmitters of postganglionic neurons innervating bladder in rats with the artificial somatic-autonomic reflex arc. VIP, NO and SP may be as the neurotransmitters or neuromodulators to participate the procedure of urinary storage and voiding. Key words: Bladder; Pelvic ganglion; Neurotransmitter; Artificial reflex arc