The Effect Of Intrathecal Dexmedetomidine On The Acute Nociceptive Action And The Change Of C-Fos Protein In Spinal Dorsal Horn

Objective:To investigate the effects of intrathecal dexmedetomidine on the acute nociceptive action and the change of c-Fos protein in spinal dorsal horn,and assess the possible mechanism,providing an effective clinical and theoretical basis for the prevention of postoperative pain.Methods:In part one,we investigate the effects of intrathecal dexmedetomidine on the acute nociceptive action;In part two,with Elisa and immune-histochemistey we detected the serum levels of inflammatory cytokines and the expression of Fos protein in spinal dorsal horn.Niety-six male SD rats weighing 250-300 g were randomly divided into 4 groups: Control group(group C,intact rats without any treatment);Operationg group(group O,(Group S,incision on the right planter surface according to the method of brennan's but no intrathecal injection);normal saline + operation group(group N,received normal saline 20 ? l before incised),and Dexmedetomidine + operation group(group D,received dexmedetomidine 1ug/kg,20?l,instead of normal saline before incised).Pain behavior was assessed at the time before incised(T0)and 0.5,1,4,8,12,24 and 48 hours after incised model established(T1~7).And arterial blood samples were taken for determination of the levels of serum TNF-a,IL-6 and IL-10.The animals were sacrificed after take blood,The lumbar segment(L4-6)of the spinal cord was isolated,and determination of the expression of Fos protein in spinal dorsal horn by immune-histochemistey.Results:(1)Compared with group C,MWT was significantly decreased and TWL was shorted in other 3 groups(P<0.05).Compared with group O,MWT was significantly increased and TWL was prolonged in groups D(P<0.05),There was no significant difference in MWT and TWL in group N(P>0.05).Compared with group N,MWT was significantly increased and TWL was prolonged in groups D(P<0.05),(2)Compared with group C,the serum TNF-a,IL-6 and IL-10 were increased in other 3 groups(P<0.05).Compared with group O,the serum TNF-a and IL-6 were decreased,serum IL-10 was increased in group D(P<0.05).Compared with group N,the serum TNF-a and IL-6 were decreased,serum IL-10 was increased in group D(P<0.05).(3)Compared with group C,the expression of c-Fos protein in spinal dorsal horn were significant increased in other 3 groups(P<0.05).Compared with group O,the expression of c-Fos protein in spinal dorsal horn were significant decreased in group D(P<0.05),and there was no significant difference in group N(P>0.05).Compared with group N,the expression of c-Fos protein in spinal dorsal horn were significant decreased in group D(P<0.05).Conclusion:Predefined intrathecal injection dexmedetomidine can reduce DEX can reduce hyperalgesia and relieve the pain perception,and down expression of c-Fos protein in spinal dorsal horn may be involved in the underlying mechanism.