Changes in expression of c-fos protein in spinal cord in a rat model of oxycodone dependence or withdrawal response / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the changes in the expression of c-fos protein in the spinal cord in a rat model of oxycodone dependence or withdrawal response.Methods Thirty SPF adult male Sprague-Dawley rats,aged 6-8 weeks,weighing 180-220 g,were divided into 3 groups (n=10 each) using a random number table method:normal saline group (group NS),oxycodone dependence group (group OD),and oxycodone withdrawal group (group OW).In OD and OW groups,oxycodone was injected subcutaneously in back,5 days in total,with the dose of 2,3,4,5 and 6 mg/kg in turn,3 times a day (8:00/15:00/22:00).The equal volume of normal saline was given instead in group NS.The mechanical paw withdrawal threshold was measured at 3 days before administration and 30 min after the last administration every day.The oxycodone withdrawal was induced by intraperitoneal injection of naloxone 4 mg/kg at 8 h after the last administration of oxycodone on 5th day in group OW.The withdrawal response scores and range of weight changes were recorded within 15 min after giving naloxone or normal saline in NS and OW groups.Spinal cord tissues were collected at 1 h after the last administration on 5th day in group OD and at 1 h after giving normal saline or naloxone on 5th day in NS and OW groups for determination of the expression of c-fos protein by Western blot.Results Compared with group NS,the mechanical paw withdrawal threshold was significantly increased on 1 and 2 days after administration,and the expression of c-fos protein in the spinal cord was up-regulated in OD and OW groups,and withdrawal response scores were significantly increased,and the range of weight change was increased in group OW (P＜0.05).The expression of c-fos protein was significantly down-regulated in group OW as compared with group OD (P＜0.05).Conclusion Oxycodone dependence or withdrawal response may be related to the expression of c-fos protein in the spinal cord of rats,and the expression is up-regulated during oxycodone dependence,while down-regulated during oxycodone withdrawal.