| Although mom - steroidal antiinflammatory drags (MSAIDs) have been extensively used in clinical painful therapy, the analgesic mechanism of NSAIDs isn't still understood completely mow. The research indicated the analgesic effect of NSAIDs was produced mot only by way of inhibiting cyclooxygenase ( COX) to restrain the synthesis of the peripheral proslaglandid { PG) , but also by way of the central and peripheral mechanism of the other, Nitric oxide which was the information earrier inside the cell and between the cell probably played an im-portant effect on the transmission of the nocieeptive information . The research indicated that nitric oxide participated in the algesia modulation of the different levels of peripheral and central nervous system.The people would pay close attention to the effect of its algesia modulation. Although β- endorphin acted as the transmitter of the central nervous system nervous modifier and hormone, but people has attached importance to its analgesic effect. Lomoxicam was one kind of the new NSAIDs in xicam family and inhibited acute- chronic inflammatory reaction more effectively than the xicam NSAIDs of the other. Hie analgesic effect of lornoxicam has been applied extensively after surgery. In the inflammatory painful model of formalin - induced rats, by way of applying nitrate reduc-lase method and radioimmunoassay , I will observe the effect of lornoxicam on the serum concentration of nitric oxide and plasma concentration of β - endor-phin in order to research the .analgesic mechanism of the lornoxicam.MethodsExperiments were performed on 30 healthy male Wistar rats, weighing 250 -280g. In addition, rats were randomized to either 1 of 5 groups( n =6 rats for each group) : Group I received a intraplantar injection of 0.1 ml of 5% formalin solution; Group II received a intraperitoneal injection of 2 ml of normal saline solution 25min prior to intraplantar injection of 0. 1 ml of 5% formalin solution; Group III received a intraperitoneal injection of 2 ml of 2mg/kg lornoxicam solution 25min prior to intraplantar injection of 0. 1 ml of 5% formalin solution; Group IV received a intraperitoneal injection of 2 ml of 4mg/kg lornoxicam solution 25min prior to intraplantar injection of 0. 1 ml of 5% formalin solution; Group V received a intraperitoneal injection of 2 ml of 8mg/kg lornoxicam solution 25min prior to intraplantar injection of 0.1 ml of 5% formalin solution. According to pain reaction weighting score of Dubbisson and Dennis, the accumulative pain score of 0 -5min ( I phase) and 15 - 60min ( II phase) after formalin injection were recorded respectively. The blood concentration of nitric oxide and endorphin were respectively measured by applying nitrate reductase method and radioimmunoassay . All data were reported as mean SD. Statistical analysis were evaluated by using one-way analysis of variance followed by LSD test. A P value of less than 0. 05 was considered statistically significant.Results(1) A intraperitoneal injection of lornoxicam solution prior to intraplantar injection of formalin could significantly inhibit the II phase reaction of formalin- induced rats dependently ( P < 0.01) , but not have significant influence on the I phase ( P>0.05).(2) The serum concentration of nitric oxide in Group I and Group II increased similarly, but didn t have difference statistically between two groups ( P> 0.05 ). Compared with Group I and Group II respectively, the serum concentration of nitric oxide of Groups III- V decreased significantly and had signifi-cant difference on the statistics ( P <0.01). Compared with each dosage group (Groups III - V ) , the difference in the statistics was also significant ( P < 0. 01).(3) Coming from the data, from Group I to Group V the plasma concentration of endorphin showed the clear increasing trends. Although plasma concentration of endorphin of Group II was slightly high than that of Group I , they didn t have difference in the statistics ( P >0.05 ). Compared with Group I and Group II re...
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