The Changes Of Nitric Oxide Synthase Positive Neurons In Antral Myenteric Plexus In Rat Severe Acute Pancreatitis

Objective: To investigate the changes of nitric oxide synthase (NOS) positive neurons in the gastric myenteric plexus of rat severe acute pancreatitis (SAP), purposing to study the mechanism of gastrointestinal dysfunction in SAP.Methods: (1) Model establishment: 30 male SPF level rats were randomly divided into sham operation group (n=10) and SAP group (n=20). SAP model was induced by retrograde cholangiopancreatic duct injection of 5% sodium taurocholate. The rats of sham operation group were treated the same way as SAP group except not given the cholangiopancreatic duct puncture. (2) Gastric emptying rate calculation: At the point of 24 hour after above treatment, all rats in both groups were given introgastically the phenol red paste. The rats were killed 20min later and the lefted phenol red paste in the stomach was collected for gastric emptying rate calculation by colourmetric analysis. (3)Morphology of NOS-IR neurons in gastric myenteric plexus: Double-immunofluorescent staining was employed for MP whole-mount preparations. The morphology of NOS-IR neurons was observed and the percentage of NOS-IR neurons was calculated based on the total neurons of Hu-immunoreactivity. (4) nNOS mRNA expression in rat gastric antrum was detected by RT-PCR.Results: (1) the sham operation group survived after 24h, SAP model was successfully copied. In SAP group 11 of the 20 rats died, 2 in 6 h, 5 in 12h , and 4 in 24h respectively. (2) Gastric emptying rate were 71.58±3.89% in the sham operation group and 31.33±6.30% in SAP group. (3)The percentage of nNOS positive neurons were 17.04±4.16% in sham operation group and 25.19±2.84% in SAP group. (4)Pancreas pathology score (points) was 1.7±0.7 in sham group, while 15.6±1.2 in SAP group. (5)nNOS expression detected by RT-PCR was 0.7013±0.0129 in sham operation group. While in SAP group, the expression of nNOS mRNA significantly increased as 0.8820±0.0151(P <0.05).Conclusion: Severe acute pancreatitis can induce the increase of NOS positive neurons in gastric antrum myenteric plexus, resulted a lower gastric emptying rate. In severe acute pancreatitis, an increase of number of NOS positive neurons may lead to an increasing release of nitric oxide (NO), which in tern leads to a dysmotility of gastrointestine.