ABSTRACT
Objective: To observe the effect of phophodiesterase 5 (PDE5) inhibitor, sildenafil on morphine withdrawal symptoms in mice. Method: A physical morphine dependent model in mice was established by subcutaneous injection of morphine in gradually increasing doses. After interperitoneal injection of naloxone (0.2mg/kg), withdrawal symptoms including jumping in 15 min, jumping latent period and weight loss were scored to evaluate the response intensity of morphine withdrawal. The effect of sildenafil (15mg/kg, 30mg/kg and 60mg/kg) was observed. Using nitrate reductase method to detect NO (nitric oxide) content in the blood and brain of mice. Result: Morphine withdrawal symptoms were aggravated by 3 different dosage of sildenafil and assumed good dose-dependent manner. NO content in blood increased after 30mg/kg sildenafil, which had no effect on NO content in brain of mice. Conclusion: Morphine withdrawal symptoms can be aggravated by sildenafil, which has also influence on blood content of NO, but has no influence on NO content in brain.