AIM: The present study investigated whether the spontaneous contraction of stomachic smooth
muscle was inhibited by injection
of botulinum toxin type A (BTX-A) into the anterior wall of gastric antrum, whether local
substance P (SP) content was al tered in the wall of gastric antrum. METHODS: 30 rats were randomly divided into botulinum toxin type A (BTX-A, B group) and control group (A group). Parenteral solution of BTX-A (2 0 U/kg in 0.3 mL) or 0.9% sodium chloride was injected into the gastric a ntrum. The gastrointestinal myoelectric activities were recorded by Biolap syste m at the same time. The rats were sacrificed at the end of recording. The change s o f SP were observed with SABC immunohistochemical method or detected with radioim munoassay in the injection site of
stomach. All the data were statistically anal yzed by paired t test or student's t test. RESULTS: ① 28% SP contents in BTX-A treatment group decreased, compared with control group, at the 24th min (radioimmunoassay method, P <0.01). Substance P immunoreactive fibers in the stomachic pyloric part showe d a remarked decrease after BTX-A application. The densities and numbers of SP-I R fibers were decreased in the gastric antrum (P<0.05). ② According to sta tistical analysis, frequency, amplitude, peak area of slow or fast wave were evidently decreased in the BTX-A treatment group at the 12th min and 24th min ( P<0.05 or P<0.01). CONCLUSIONS: ① The initial pilot study suggests that BTX-A in jection at the anterior wall of stomach leads to reduction in contents of SP sig nificantly. ② Frequency, amplitude, and peak area of slow and fast wave are i nhibited by BTX-A.