Choline acetyltransferase-and nitric oxide synthase-containing neurons of the major pelvic ganglion projecting to the external urethral sphincter in rats

Abstract

Objective To observe the choline acetyltransferase (ChAT)-and nitric oxide synthase ( NOS) -containing neurons of the major pelvic ganglion ( MPG) projecting to the external urethral sphincter (EUS). Methods Twenty-four Sprague-Dawley rats were divided into two groups: group A (n = 12) and group B (n = 12). In group A, the pelvic ganglia neurons innervating the EUS were labeled by retrograde axonal tracing methods with the use of horseradish peroxidase (HRP) injected into the EUS and identified with TMB-HRP reaction. Then immunohistochemical (ChAT) and histochemical methods ( NADPH-diaphorase activity and nitric oxide synthase immunoreactivity) were used to identify the neurotransmitters of HRP-labeled neurons projecting to the EUS. In group B, Malt agglutinator binding horseradish peroxidase (WGA-HRP) was injected into the MPG for antegrade tracing. Results In group A, HRP-labeled neurons with spherical or oval shape mainly distributed in the MPG. The HRP-labeled neurons were positve for ChAT (155/358, 43.3%) and NOS (49/339, 14.5%), respectively. In group B, HRP positive axon terminals were observed in the EUS after WGA-HRP was injectec into MPG. Conclusion ChAT and NOS-containing neurons of the major pelvic ganglion project to the ELS. Acetylcholine and nitric oxide may be as neurotransmitters or modulators to participate the procedure of urinary storage and voiding. Key words: Pelvic ganglion; External urethral sphincter; Choline acetyltransferase; Nitric oxide svnthase