| Intestinal tract has a complex enteric nervous system (ENS). ENS is controlled by the central nervous system, and on the other hand, it adjusts the smooth muscle motility and the secretion of intestinal tract to maintain its physiological function. Recent years' study shows that some autoimmune or functional diseases, such as irritable bowel syndrome (IBS), were related with the abnormal regulations of intestinal tract neurotransmitters. Nitric oxide is a suppressive neurotransmitter of intestinal tract, which plays an important role in non-adrenergiccholinergic regulation of smooth muscle contraction. Endogenous nitric oxide is derived from L- arginine under the catalysis of nitric oxide synthase. NOS has three types: neuronal NOS (nNOS), endothelial NOS (eNOS) and inducible NOS (iNOS). Neuronal NOS distributes extensively in brain, spinal cord and autonomic nervous system, and nitric oxide derived from nNOS is an important cellular signal molecule and neurotransmitter. Few studies about the distribution of nNOS in intestinal tract were reported in recent years.Endogenous carbon monoxide (CO) is another important gaseous signal molecule. Endogenous CO in mammal is derived from protoheme under the catalysis of heme oxygenase (HO), which depends on NADPH and cytochrome P450. HO is a singular rate-limiting enzyme for CO production and has three types: HO-1, HO-2 and HO-3. Among the three types, HO-1 is a heat shock protein (HSP), an inductive form. HO-2 distributes over almost all kinds of tissues, and is up regulated by adrenal cortical hormone. CO derived from HO-2 is else a suppressive neurotransmitter. Lots of studiesshow that CO and NO coexist in some neurons in brain and autonomic ganglia, and are two important neurotransmitters. CO and NO may play a synergic and complementary role in cellular signal transmission. Few studies about the distribution of heme oxygenase-2 in intestinal tract had been reported.Recent years' studies indicated that there was an intimate relationship between stress and the development, progress of some intestine functional diseases and autoimmunue diseases. Stress may result in disorders of intestine tract function. Stress may evoke and aggravate the symptom of irritable bowel syndrome (IBS). But the effect of stress on the expression of nNOS and HO-2 in intestine tract remains unknown, and furthermore, the expression of nNOS and HO-2 in intestine tract after stress in rats had not been reported.The aim of present study is to detect the expression of nNOS and HO-2 in colon after water immersion-restraint (WRS) stress in rats with immunohistochemistry, and indicate the effect of stress on the distribution of nNOS and HO-2 in colon, and else provide a new idea for making IBS model.Materials and Methods1. Animals and ModelForty male SD rats weighing 200~220g (provided by Experiment Animal Center of Zhejiang Province) were randomly divided into four groups: stress group (n=10), L-NAME + stress group (n=10), ZnPP + stress group (n=10) and control group (n=10). Water immersion-restraint stress (WRS) model was performed, and WRS lasted for 4 hours.2. MethodsAfter the WRS model was prepared, glandular stomach of control and model rats were detected pathologically to observe gastric mucosa lesion. The colon specimens were fixed in 4 percent formaldehydum polymerisatum and embeded with paraffine. Colonic serial sections (4 urn) were prepared for pathological observation and immunohistochemistry determination. Using anti-nNOS and anti-HO-2, we detected theexpression of nNOS and HO-2 of colon specimens with SABC immunohistochemistry. Image analysis and quantitative determination were used for immunohistochemistry results. Data were expressed with mean ?standard deviation (x s ) SPSS 10.0 statistical software was applied for statistical analysis.Results1. Pathological observations: There was no lesion in the gastric mucosa of control group rats. In stress groups, lots of bloodstain on the surface of gastric mucosa, scatterd spot and linear erosions and hem...
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