Effect Of Neonatal Fentanyl Analgesia On Visceral Pain Sensitivity And Spinal Fos Expression In Visceral Hyperalgesia Rats

Objective To explore the effect of Fentanyl analgesia in neonatal period on visceral sensibility of pain in visceral hyperalgesia rats by the method of behavior and electrophysiology research. Observeing the c-fos expression of lumbosacral spinal dorsal horn in developing rats. To investigate the mechanism of blocking visceral hyperalgesia by Fentanyl analgesia in neonatal period . This study can provide the theoretical basis of treatment and prevent for the abdominal pain related to functional gastrointestinal disease in children.Method①According to the factorial design, 32 SD rats were divided into four groups with each 8, GroupA1B1:establish the model of visceral hyperalgesia in developmental rats, and intraperitoneal inject Fentanyl before colorectal irritation (CI) stimulation in neonatal period, GroupA1B2:. establish the model of visceral hyperalgesia in developmental rats, but Administration saline before neonatal CI,GroupA2B1: not imposed on CI at neonatal period and, and intraperitoneal inject Fentanyl ,Group A2B2: not imposed on CI at neonatal period, but Administration saline. Rats in the modeling group were treated with colorectal irritation once a day during 7 consecutive days from the 8th day after birth, the control rats were not except handled in the same way.Conventionally breeding to the young period (6-week age), observing the score of Abdominal Withdrawal Reflex,visceral pain threshold and measurement of electrical discharge of external oblique muscle of abdomen under different pressures of colorectal distension irritation (CRD) to evaluate visceral algesthesia in rats.②32 SD rats were treated with as above,.On the 6th week, rats were sampled the spinal cord from L6 to S2, the semi-quantity analysis of staining density and the cell numbers of Fos-Like Immunoreactivity of spinal cord were made through immunohisrochemical coloration and computer image analyzing system. SPSS 13.0 software for Windows was used in all statistical tests.α=0.05 was considered significant.Result①The AWR score increased gradually with the rising of the CRD pressure in developing rats; neonatal Fentanyl analgesia and modeling effects on the AWR score, modeling can make The AWR score increase. When the CRD pressure were20mmHg, 40mmHg,60mmHg, the differences had statistical significance(P<0.001). But when pressure reached 80 mmHg, there was no significant difference of AWR scores increase(P>0.05). Neonatal Fentanyl analgesia can make The AWR score decrease. When the CRD pressure were20mmHg,40mmHg,60mmHg, the differences had statistical significance(P<0.05). But when pressure were40mmHg,60mmHg,80 mmHg, there was no significant difference of AWR scores increase(P>0.05). When the CRD pressure were20mmHg,40mmHg,60mmHg , there were interaction between neonatal Fentanyl analgesia and modeling on affecting the AWR scores.But when pressure were80mmHg, there was no interaction. Modeling can make The Pain Thresholds of rats increase, neonatal Fentanyl analgesia can make The Pain Thresholds of rats decrease. the differences had statistical significance, (F=108.08,P<0.001 F=4.421,P<0.05). There was interaction between neonatal Fentanyl analgesia and modeling on affecting The Pain Thresholds.②With the CRD pressure increased, The amplitudes of spike of EOMA increased too; neonatal Fentanyl analgesia and modeling effects on the spikes, modeling can make the spikes increase. When the CRD pressure were15mmHg,30mmHg,45mmHg, the differences had statistical significance(P<0.05). But when pressure reached 60mmHg,75mmHg, there was no significant difference of spikes increase(P>0.05). Neonatal Fentanyl analgesia can make The spikes decrease. When the CRD pressure were15mmHg,30mmHg,45mmHg, the differences had statistical significance(P<0.05). But when pressure reached 60mmHg,75mmHg, there was no significant difference of spikes increase(P>0.05). When the CRD pressure were30mmHg, there were interaction between neonatal Fentanyl analgesia and modeling on affecting the spikes. But there were no interaction at the other pressure.③modeling can make the number of FLI increase and integral opticaldensity of FLI significantly decrease in lumbosacral spinal dorsal horn, neonatal Fentanyl analgesia can make them decrease , the differences all had statistical significance.There was interaction between neonatal Fentanyl analgesia and modeling on affecting the number and staining density of FLI.Conclusion The persistent stimulation of CI in neonatal phase resulted in low pain threshold and chronic high visceral pain sensitivity,, thus it can be the model of visceral hyperalgesia. neonatal Fentanyl analgesia can inhibit visceral hyperalgesia, block central sensitization of spinal, result in decreasing of the c-fos expression.