| Background and Aims: Botulinum toxin A(BTA) was widely used in various neuromuscular disorders, a majority of gastrointestinal disorders. One attribution of these diseases is motility disorder or spasm. Besides inhibiting the release of the neurotransmitter (ACh) at the neuromuscular junction, clinicians have reported that some reduction of pain occurs before muscular improvement, suggesting that BTA may have a more complex mechanism of action on pain system. The aim of this study was to observe whether BTA can affect gastrointestinal motility and so AChE, SP and β-Endorphin expressed in digestive tract in normal rats and develop potential treatment for functional gastrointestinal disorders.Materials and Methods: 48 Wistar rats of 8 weeks age were divided into four groups randomly and every group contained 12 rats. 2.0mL saline containing 4units BTA was injected in every rat peritoneally in group A, 2 units in group B, and 1 unit in group C. Only 2.0mL saline was injected in group D. All animals eating and drinking freely were reared alone. Thedefecation frequency——granule per day, food in-taking——gram per 48hours and body weight were recorded after administration. At the end of 4 weeks, 6 rats containing 3 males and 3 females in every group were performed with rectal balloon distention to evaluate viscero-sensibitity and then carbon pushing test of small intestine. The samples of small intestine, ileocecal junction and distal colon was stained by Haematoxylin-eosin forthe routine pathologic examination n toluidine blue improved staining method for mast cell and immunohistochemistry for AChE> SP^ /?-EP. The expression of AChE-> SP and /?-EP were analyzed by computing image analysis system of image-pro plus 4.5 semi-qualitively. The other animals were reared till 12th-weeks end and were used to repeat the preceding programs.Results: There was a transient decrease of defecation frequency only in group A(P<0.05 compared with group D). No differences in moisture contents in stool > body weights and food in-takings were found in all groups. Neither reflex threshold with rectal balloon distention nor reflex times with fixed volume detention was of different. The lengths of carbon pushing in small intestine in both group A (53.89±3.98%) and B(53.21±2.96%) were shorter compared with group D (66.41±5.56%) (P<0.05). The numbers of mast cell in small intestine^ ileocecal junction and large colon in both group A and B were less than that of group D(P<0.05). The expression of AChE^ SP in all samples in both group A and B had a decrease than that of group D (P<0.05), but /?-EP in small intestine in both group A and B, and large colon in group B were more than that of group D(P<0.05). The blood plasm content of /?-EP in all groups had no difference both at the end of 4 weeks and 12 weeks. At the end of 12 weeks, the numbers of mast cell remains less in group A and B; the expression of AChE was less in all samples in group A and B(P<0.05 compared with group D); and the same result of SP was observed excluding the mucosa of large colon in group B. The content of /?-EP in small intestine mucosa of group A and B were higher than that of group D; no difference in other samples and group C was found. The decrease of carbon pushing in small intestine in group A and B reversed to normal. Group C was not affected by the drug in all theses figures at both 4 weeks and 12 weeks after administration compared with group DConclusions: Injection of botulinum toxin A in rats intraperitoneally... |
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