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.

The distribution of virus antigen of epidemic hemorrhagic fever (EHF) in infected suckling mice brain was studied by indirect immunofluorescence procedure. The specific fluorescence was presented in the following areas: (l)the limbic system, including the cingulate cortex, the piriform cortex, the anterior olfactory nucleus, the lateral septal nucleus, the hippocampus, the dental gyrus, the dorsomedial nucleus and lateral nuclei of thalamus, and several nuclei of the hypothalamus; (2)the special sensory nuclei, such as the medial and spinal vestibular nuclei, the cochlear nucleus, and the lateral lemniscus nucleus; (3)the nuclei associated with analgesic function, including the periaqueductal gray substance, the trigeminal sensory nucleus, the raphe nuclei of midbrain etc; (4)the extrapyramidal structures, for example, the caudal-putamen, the pallidum, the entopeduncular nucleus, the cerebellum and several nuclei of reticular formation in brainstem.