Role of cerebrospinal fluid-contacting nuclei in maintenance of chronic itch in rats / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the role of cerebrospinal fluid-contacting nuclei (CSF-CN) in maintenance of chronic itch in rats.Methods Forty-two adult male Sprague-Dawley rats,aged 3 months,weighing 240-280 g,were used in the study.The experiment was performed in two parts.Part Ⅰ Forty-two Sprague-Dawley rats were randomly divided into 3 groups (n =14 each)control group (C group),acetone group (A group) and oxazolone group (O group).0.5％ oxazolone 15 μl was applied to the neck and back of rats in group O,while the equal volume of normal saline and acetone was applied in groups C and A,respectively.Application of the drug mentioned above was repeated on day 7,9,13,16,17,18,21 and 23 after the first stimulation in each rat in each group.Scratching behaviors were oberserved within 30 min after each stimulaiton.Six rats in each group were chosen and sacrificed after the last application of oxazolone,and the brains were obtained for determination of c-Fos expression in CSF-CN.Part Ⅱ Twenty-four rats were randomly divided into 3 groups (n =8 each)control group (C1 group),chronic itch group (group CI),and chronic itch + lesion group (CI + KA group).Chronic itch was induced by repeated application of oxazolone as previously described in CI and CI + KA groups.The chemical lesion of CSF-CN was performed at 6 h after 8th application of the drug.Then the scratching behaviors were observed within 30 min after 9th application of the drug.Results Part Ⅰ Compared with C group,the scratching behaviors were increased significantly at T4-8 in A group,and at T1-8 in O group (P ＜ 0.05),and the expression of c-Fos was up-regulated in O and A groups (P ＜ 0.05).Compared with A group,the scratching behaviors were increased significantly at T1-8 and the expression of c-Fos was up-regulated in O group (P ＜ 0.05).Part Ⅱ Compared with C1 group,the scratching behaviors were significantly increased in CI and CI + KA groups (P ＜ 0.05).The scratching behaviors were significantly reduced in CI + KA group compared with CI group (P ＜ 0.05).Conclusion CSF-CN is involved in the maintenance of chronic itch in rats.