| Objective: To evaluate the effects of intrathecal dexmedetomidine on spinal function and toxicity induced by ketamine in neonatal rats.Methods: A total of 104 healthy SD rats(8-11g) were randomed divided into four groups : Control group(group C);Dexmedetomidine group(group D); Ketamine group(group K);Dexmedetomidine and ketamine group(group KD). In group C,D,K,KD, were received intrathecal respectively normal saline, dexmedetomidine, ketamine,dexmedetomidine and ketamine. The spinal reflex function was assessed by evaluating the mechanical withdrawal thresholds. The lumbar segment(L4-5)of the spinal cord was removed for microscopic examination. Spinal tissue was analysed for activated caspase-3 using monoclonal anti-activated caspase-3. An Apoptosis count of the spinal tissue was also measured by Fluoro-Jade C staining and TUNEL. Glial reactivity was assessed by ionized calcium binding adapter molecule 1 after 7 days following injection. Long-term spinal function in rat pups on P35 was evaluated by measuring the hindlimb withdrawal thresholds and gait analysis.Results:(1)HE staining : The pathological changes of spinal cells swelling, shrinkage and lack in group K, group KD showed slightly reduced nerve cells, a small cell body shrink,loosely arranged, showing perinuclear chromatin mild dissolution, only a small vacuole formation.(2) Compared with group C, MWT was significantly increased, The neuron apoptosis number,Iba1 and caspase-3 protein expression were significant increased among group K(P<0.05);Compared with group K,MWT was significantly decreased and the neuron apoptosis number and caspase-3 protein expression were significant decreased among group KD(P<0.05).(3) Compared with group K, MWT was significantly decreased and gait was improved in p35 among group KD(P<0.05).Conclusion: Intrathecal dexmedetomidine can reduce spinal cord toxicity induced by ketamine in neonatal rats,and inhibition of apoptosis in the spinal cord may be involved in the underlying mechanism. |
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