小剂量辣椒素对大鼠内脏机械及化学刺激敏感性的影响

Effects of low dose of capsaicin on sensibility of visceral mechanical and chemical stimulation in rats

目的研究小剂量辣椒素(Cap)在不同时期对大鼠内脏机械及化学刺激敏感性的影响。方法SD大鼠160只,随机分为对照组(普通饲料)和观察组(Cap 1 mg·kg-1·d-1),每组80只,再各随机均分为5组,雌雄各半,分别在干预1 d、3 d、1周、2周和4周后,采用直肠气囊扩张法观察大鼠内脏机械刺激敏感性,腹腔注射新斯的明法观察内脏化学刺激敏感性,采用免疫组化法检测胃、十二指肠黏膜辣椒素受体(TRPV1)的表达情况。结果在机械刺激敏感性实验中,与对照组相比较,喂食Cap 1周,观察组大鼠气囊扩张体积显著减少(P=0.002),且雌性较雄性更敏感(P=0.001);喂食Cap 4周,观察组大鼠气囊扩张体积显著增加(P=0.007)。在化学刺激敏感性实验中,与对照组相比较,喂食Cap 1周,观察组大鼠腹痛相关行为的持续时间显著延长(P=0.001);而喂食Cap 4周,观察组大鼠腹痛相关行为的开始时间显著延长(P=0.02);其余各组之间差异无显著意义(P>0.05)。观察组在给予Cap 1 d、3 d、1周后胃黏膜TRPV1的表达显著高于对照组(P<0.05),给予Cap 1 d、3 d后十二指肠黏膜TRPV1表达显著高于对照组(P<0.05),随后观察组和对照组TRPV1的表达均无显著差异(P>0.05)。结论连续摄入小剂量Cap 1周后,大鼠对内脏机械及化学刺激的敏感性显著增加,2周后恢复正常,4周后显著降低,其中雌性对内脏机械刺激较雄性更为敏感。小剂量Cap可以调节胃、十二指肠组织TRPV1的表达。

AIM To investigate the effects of low does of capsaicin （Cap） on sensibility of visceral mechanical and chemical stimulation in rats. METHODS A total of 160 SD rats were randomly divided into control group （common feed） and study group （Cap 1 mg.kg-1.d-1）. Each group had 80 rats. Then each group was randomly divided into five stages （feed 1 d, 3 d, 1 week, 2 weeks and 4 weeks） with half male and halffemale. The visceral sensitivity to mechanical stimulation was observed by expanding the balloon in the rectal. The chemical stimulation was induced by injecting the neostigmine into intraperitoneal. The expression of transient receptor potential cation channel subfamily V member 1 （TRPV1） in mucosal of gastric and duodenal was observed by immunohistochemical. RESULTS In the visceral sensitivity to mechanical stimulation experiment, the balloon dilatation volume in the study group were significantly lower than the control group when feeding 1 week （P = 0.002）. Furthermore, females were more sensitive than males （P = 0.001）. When feeding 4 week, the study group was significantly higher than the control group （P = 0.007）. In the visceral sensitivity to chemical stimulation experiment, when feeding 1 week, the duration time of the abdominal pain in the study group was significantly longer than the control group （P = 0.001 ）. When feeding 4 week, the beginning time of the abdominal pain in the study group was significantly longer than the control group （P = 0.02）. TRPV1 expressionsin the study group were significantly higher than the control group in gastric tissue when feeding 1 d, 3 d and 1 week （P 〈 0.05）. TRPV1 expressions in the study group were significantly higher than the control group in duodenum tissue when feeding 1 d and 3 d （P 〈 0.05）. CONCLUSION The sensitivity to mechanical and chemical stimulation was significantly increased after 1 week by low dose of Cap feeding in rats, and returned to normal after 2 week, then reduced significantly after 4 week. Furthermore, females were more sensitive than males to mechanical stimulation. The expression of TRPV1 in the gastric and duodenal tissues was regulated by Cap in low dose.