Use of synaptophysin immunohistochemistry in intestinal motility disorders

The purpose of this study was to describe synaptophysin (SY) immunoreactivity in colonic specimens from patients with Hirschsprung's disease (HD), chronic constipation (CC), or anal atresia (AA). This membrane protein is specific for the synaptic vesicles in the central and peripheral nervous system and responsible for neurotransmission. Biopsy specimens of the intestinal wall were obtained from 18 patients (age range, 2 days to 7 years). Immunohistochemistry was performed using rabbit anti-human antibodies specific for synaptophysin (DAKO). In the ganglionic colon of HD patients and others the immunoreactivity of SY-positive synapses was abundantly present in the smooth muscle layers. Distinct immunoreactivity showed ganglion cells and nerve fibers inside circular and longitudinal muscle layers. In some non-HD patients' colonic specimens SY-positive synapses were present in the muscularis mucosae. In the aganglionic colonic segment of HD-patients no immunoreactivity of synapses and ganglions was seen. In the transition zone, where ganglion cells appeared sporadically, synapses were very rarely present. In two patients from the CC group the amount of visualized synapses was clearly smaller and the concentration of ganglion cells within ganglions in these cases was much lower than usual (but still within normal ranges). In the AA group in the distal part of the atretic rectum (at the place where the fistula was cut) SY-positive synapses were present in smooth muscle layers and small dysplastic ganglions were seen in the submucosal and muscular region, but not in large numbers. These patients had a normal distribution of ganglion cells and synapses at the place of colostomy. Synaptophysin immunohistochemistry is an indirect labeling method with a high detection rate for intestinal ganglion cells by demonstrating their synapses. Changed intestinal distributions of SY-positive synaptic vesicles usually accompany colonic ganglion cell disorders. The pattern of SY-positive synapses distribution in circular and longitudinal colonic muscles and intermuscular ganglions can reflect functional disturbances of large bowel motility and could be helpful in the description of the innervation status of colonic specimens in HD patients.