Effect Of Hyperbaric Lidocaine On Spinal Cord Neurons Apoptosis In Diabetic Neuropathic Painful Rats

Objective:To investigate the effect of intrathecal hyperbaric lidocaine on spinal cordneurons apoptosis in diabetic neuropathic painful rats.Methods:Sixty healthy male Sprague-Dawley rats weighing220-300g,10normal ratsrandomly served as control group (C),the fifty rats were intraperitoneal injection1%streptozotocin (STZ)60mg/kg to induce diabetic neuropathic pain(DNP),andinduced forty-five diabetic neuropathic painful rats.Group C and diabetic neuropathicpainful rats administer intrathecal catheter,respectively,eight and twenty-four ratswere successful.Twenty-four rats in which DNP was successfully intrathecal catheterwere randomly divided into3groups (n=8each):hyperbaric lidocaine group (HL),isobaric lidocaine group (IL), glucose group (G).Hyperbaric lidocaine10ul wereinjected intrathecally in groups C and HL,isobaric lidocaine10ul were injectedintrathecally in group IL,6%glucose10ul were injected intrathecally in groupG,once daily for3d.After all rats each administration2min,motor block durationwere recorded;Before intraperitoneal injection STZ (T0), after STZ14d (T1),28d (T2),after30min intrathecal injection1,2,3d namely32d (T3),33d (T4),34d (T5) and39d(T6),all rats paw withdrawal threshold to von Frey filament stimulation (PWT) weremeasured and fasting blood glucose value were recorded,with after STZ3d (Tis).Allrats were sacrificed at T6and their lumbar4~5spinal cord tissue were removed formicroscopic examination.And using TUNEL assay to measure spinal neuronalapoptosis.Result:(1) There was no significant difference among all groups of PWT at T0(P>0.05).When compared with T0, the PWT in HL, IL and G groups at T1all decreasedsignificantly(P <0.05).When compared with T0, the PWT in HL, IL and G group atT2~5all decreased significantly(P<0.01).Compared with T2~5, the PWT in HL groupincreased significantly at T6(P <0.05).Compared with IL group,the PWT in HL group was higher significantly at T6(P <0.05).(2) There was no significant difference among all groups of fasting bloodglucose value at T0(P>0.05).Compared with C group,the fasting blood glucose valuein HL, IL and G group were all higher significantlyat Tisand T1~6(P<0.01),and eventhe fasting blood glucose value were higher than16.65mmol/l.There were nosignificant differences among HL, IL and G group of fasting blood glucose value atTisand T1~6(P>0.05).(3) After intrathecal injection, all rats moved normally in G group. Paralyseswere seen in rats’ hind limbs but not in forelimbs and heads in HL, IL and C group.Compared with HL group, motor block duration were shorter in IL and C group(P<0.05).(4) HE staining:The HL group rats’ spinal cord tissue structure was fuzzy andappeared slight edema,neuron’ nucleus appeared wide slightly in lightmicroscope.There were slight pathologic injury at spinal cord in IL,C group,butalmost normal.There were no significant spinal cord injury in G group.(5) Compared with IL,G and C group,there were more TUNEL-positive cells atspinal cord in HL group(P<0.01).There were few positive cells in IL,C group,but notstatistically significant(P>0.05).Compared with G group,there were not statisticallysignificant in IL,C group(P>0.05).There was not positive cell in G group.Conclusion:Intrathecal administration hyperbaric lidocaine can promote spinal cord neuronalapoptosis in diabetic neuropathic painful rats.