［摘要］目的：研究山莨菪碱对利血平大鼠胃粘膜损伤的影响及其作用机制。方法：利用利血平大鼠胃粘膜损伤模型，观察腹注山莨菪碱对利血平大鼠胃粘膜损伤、胃酸分泌、胃粘液分泌、胃运动、胃粘膜血流量及胃粘膜一氧化氮含量和一氧化氮合成酶活性变化的影响。结果：山莨菪碱能抑制利血平大鼠胃粘膜损伤灶的形成；山莨菪碱能抑制利血平大鼠胃酸分泌，但对胃液分泌的量无影响；山莨菪碱能促进利血平大鼠胃粘液分泌和胃粘膜血流量，抑制胃的运动；山莨菪碱能抑制利血平导致的大鼠胃粘膜一氧化氮含量的降低和一氧化氮合成酶活性的降低。结论：山莨菪碱抑制利血平大鼠胃粘膜损伤的形成与其抑制胃酸分泌、胃的运动，促进胃粘液分泌、增加胃粘膜血流量有关；NO可能在介导山莨菪碱抑制利血平大鼠胃粘膜损伤形成中有重要作用。

［中图分类号］ R 961 R 961［文献标识码］ A

［文章编号］1000-4718(2000)03-0237-06

Effect of anisodamine on the reserpine-induced gastric mucosal lesion in rats

WAN Jun-li

(Department of Biology, Yantai Teachers College, Yantai 264025， China)

［Abstract］AIM: To determine the effects of anisodamine (Ani) administered intraperitoneally on the gastric mucosal lesion induced by reserpine.METHODS:In reserpine-treated rats, gastric mucosal lesion, gastric acid secretion, gastric barrier mucus secretion, gastric contraction, gastric mucosal blood flow (GMBF), gastric mucosal nitric oxide synthase (NOS) activity and nitric oxide (NO) content were examined.RESULTS:Ani in doses of 1,5 and 10 mg/kg significantly inhibited the formation of gastric lesions induced by reserpine, with the suppressive rate of 60.0%, 66.7% and 76.6%, respectively. Ani (10 mg/kg) significantly inhibited the secretion of gastric acid, but had no effect on the volume of gastric juice. Ani (10 mg/kg) significantly prompted the secretion of gastric barrier mucus. Our findings also showed that Ani (10 mg/kg) significantly suppressed the frequency and amplitude of gastric contraction. Ani (10 mg/kg) significantly prompted GMBF. In reserpine treated rats, gastric mucosal NOS activity and NO content were decreased and Ani (10 mg/kg) could inhibit the decrease in NOS activity and NO content.CONCLUSIONS:The protective effect of Ani may results in part from inhibiting gastric acid secretion, prompting gastric barrier mucus secretion, suppressing gastric contraction and improving GMBF. NO seems to play an important mediator role in the Ani protective mechanisms.

［MeSH］Gastric mucosa; Reserpine; Nitric oxide

［CLC number］R961［Document code］A

INTRODUCTION

Anisodamine (Ani) is an alkaloid initially isolated from Anisodus tanguticus Pasch in China. As an analog of atropin, Ani has numerous pharmacological effects such as antiacetylcholine, antishock, improving micro-circulation, inhibiting platelet aggregation, antiarrhythmia and calcium antagonistic action. It has been extensively used to treat endotoxin shock, spasm of gastrointestinal and other visceral smooth muscle etc.

Yong et al^［1］ reported that Ani administered orally was found to antagonize the gastric mucosal damage induced by indomethacin, restraint, pyloric ligation or absolute ethanol ingestion in rats. Our previous study demonstrated that intraperitoneal Ani protected the rats from contracting gastric lesion induced by restraint water-immersion^［2］. The effect of Ani on gastric lesion induced by reserpine, as well as its underlying mechanism, however, remains to be studied.

Recent studies have shown that reduction in endogenous nitric oxide (NO) seems to be responsible for the gastric mucosal injury induced by ethanol^［3］, ischemia-reperfusion^［4］ and cold restraint stress^［5］. Nevertheless, whether NO reduction is implicated in the reserpine-induced gastric lesion has not yet been investigated.

Therefore, the aims of this study are to investigate:(1) whether or not Ani administered intraperitoneally can protect against gastric lesion induced by reserpine in rats, (2)if Ani does give protection, by what mechanisms? and (3) the possible implication of NO in the Ani protection.

MATERIALS AND METHODS

1. Animal preparation Sprague-Dawley rats of either sex (150～220 g)， kept in individual cages with a raised mesh bottom each, were deprived of food but allowed free access to water for 24 h prior to the experiments.

2. Experimental procedure

Experiment I. Production of gastric lesion and measurement of gastric lesion indices The animals were divided into four groups. Group I (control) received saline (5 mL/kg) intraperitoneally. Group Ⅱ，Ⅲ, and Ⅳ received Ani in doses of 1,5 and 10 mg/kg intraperitoneally, respectively. Thirty minutes later, the rats were given reserpine in a dose of 5 mg/kg for each animal intraperitoneally. The rodents were killed by cervical dislocation 6 h after the reserpine injection. Their stomachs were immediately removed, inflated by injecting 10 mL of 10% formalin and immersed in 10% formalin for 10 min. The stomachs were then opened along the greater curvature. The sum of the length of each lesion was expressed as gastric lesion index (mm), as described by Guth et al.

Experiment Ⅱ. Measurement of gastric acid secretion Gastric acid secretion was measured in pylorus-ligated rats. The animals were divided into three groups. Group I: saline group; group Ⅱ： reserpine group; group Ⅲ： Ani group. Saline (5 mL/kg) was given intraperitoneally in group Ⅰ and Ⅱ； Ani (10 mg/kg) was given intraperitoneally in group Ⅲ， respectively. Thirty minutes later, the pyloric ends of the stomachs were tied off under ether anesthesia. Immediately thereafter, reserpine (5 mg/kg for each rat) was administered intraperitoneally in group Ⅱ and Ⅲ, and saline was given in group I. Six hours after pylorus ligation, the animals were killed by cervical dislocation, then the stomachs were removed and the gastric contents were separately drained into graduated centrifuge tubes. After centrifugation at 3 000 r/min for 10 min, the supernatants were carefully decanted and assayed for the volume of the gastric juice and its H⁺ concentration. The H⁺ concentration was determined by titrating the gastric juice to pH 7.0 with 0.01 mol/L NaOH. Volumes of gastric secretion, total acid output and titratable acidity were expressed as mL of gastric juice/100 g body weight, μmol of H⁺/100 g body weight and mmol of H⁺/L, respectively.

Experiment Ⅲ. Measurement of gastric barrier mucus Gastric barrier mucus was determined according to the modified procedure of Bolton et al. The animals were divided into three groups and treated as in experiment Ⅱ. Six hours after reserpine injection, the animals were killed and the stomachs removed. The stomachs were opened along the lesser curvature and free mucus was gently removed from the surface of the gastric mucosa. Each of the stomachs was then placed separately in 20 mL Alcine Blue solution (20 mg Alcian Blue was dissolved in 100 mL McIlvaine buffer, pH 5.8) and incubated for 2 h at 20℃, followed by centrifugation at 4 000 r/min for 10 min and the supernatants were used for measuring absorbance at 615 nm on a spectrophotometer. Gastric barrier mucus was calculated using the following formula:

gastric barrier mucus (mg)=4-4×(test absorbance)/(standard absorban