Change of substance P containing neural pathway in rat model of irritable bowel syndrome

Abstract

AIM: To investigate the expression of substance P (SP) and c-fos in the enteric nervous system (ENS) and central nervous system (CNS) of a rat model of constipation-pre- dominant irritable bowel syndrome (C-IBS), and to explore the possible role of SP-immunoreactive nerve fibers in IBS. METHODS: The rat model was established by intragastrical injection with ice-cold water (0-4 ). The expressions of SP and c-fos in the ENS and CNS of model group (n = 10) and control group (n = 10) were detected by immunohis- tochemistry, and analyzed semi-quantitatively by comput- erized color image analyzer. The statistical differences of the opacity density (OD) and immunoreactive areas (IA) between the two groups were examined by t-test. RESULTS: The expressions of SP in ileocecus, colonic myenteric plexus, spinal dorsal horn, hypothalamus, and the fore part of gyrus cinguli were significantly higher in model group than those in the corresponding regions of control group (OD: 176.6 vs 155.5, 172.3 vs 152.0, 182.1 vs 160.2, 128.3 vs 117.9, 127.9 vs 114.5, P <0.05; IA: 169318 vs 137655, 144728 vs 114403, 145117 vs 117612 except in ileocecus and colonic myenteric plexus, P <0.05). The expression of c-fos in the above tissues was significantly higher in model group than that in the corresponding regions in control group (OD: 120.9 vs 109.0, 101.3 vs 92.2, 125.4 vs 88.7, 115.5 vs 88.6, 120.6 vs 105.1, P<0.05; IA: 191 712 vs 154 363, 73 597 vs 41 179, 46 258 vs 33 238, 302 369 vs 204 563, 708 506 vs 409 856, P <0.05). There was a close correlation between the expression of SP and c-fos in the same region (r = 0.594-0.721, P <0.05). CONCLUSION: The abnormal SP immunoreactive nerve fibers may be involved in the pathogenesis of IBS. SP containing neural pathway may play an important role in the regulation of the gastrointestinal function.