AIM: To study the protective effect and mechanism of melatonin on learning and memory in mice with repeated cerebral ischemia and reperfusion and its mechanism. METHODS: The models of repeated cerebral ischemia reperfusion were established in mice. The function of learning and memory was tested by the electric mare method, and the concentrations of MDA and NO were measured by colorimetric method and nitric reduction method in brain tissue. RESULTS: MT could obviously improve the function of learning and memory of model mice, inhibit cerebral dropsy, and lower the content of MDA and NO in cerebral tissue. CONCLUSION: MT shows significantly protective effect against repeated ischemia reperfusion injury in mice, and the mechanism might be related to inhibit the rise of MDA and NO in brain tissue.

Objective: To observe the effect of urapidil (agonist of 5-HT 1A receptor ) on morphine withdrawal syndrome Method: A physical dependent model in mice was established by subcutaneous injection of quantitative morphine The intensity of withdrawal syndrome was evaluated by observing jumping latency, jumping times and lose of body weight after intraperitoneal injection of naloxone (5 mg/kg) The effect of urapidil was observed after intraperitoneal injection it with 3 different dosages (100, 200, 400 mg/kg) Contents of NO in plasma and brain tissue were measured by nitrate reduction method Results: Morphine withdrawal syndrome was inhibited by urapidil at any dosage Content of NO in brain tissue reduced by urapidil 400 mg/kg, while plasma NO increased Conclusion: Urapidil inhibits morphine withdrawal syndrome in mice, increase the content of NO in their brain tissue