| The paraverbural block(PVB) with adriamycin(ADM) is well-used in the pain clinic, but the basic machnism involved is largely unknown. Since the ADM has the self-fluorescence specific and retrograde axonal transportation, it is possible to investigate its absorption, transfer and aggregation by the neuron through the fluorescence light microscope. We observed the fluorescence associated with ADM in spinal, dorsal root ganglia(DRG) and anterior root(AR) of the spinal nerve, concluded whether paraverbural block with ADM has the site-specific effection on the dorsal root ganglia.Material and method24 adult rabbits were set into three groups randomly ( 8 in each). After anesthesia, all the rabbits were exposured the right LI and L5 intervertebral foramina through incision. The ADM was injected into the L5 intervertebral foramina of all the rabbits at a dose of 0.1 ml/kg, at the concentration of 0.1% for group 1, 0.33% for group2, 1% for group3, respectively. O.lml/kg saline was injected into the right LI intervertebral foramina as control. The rabbits were fixed as left side-lying position for at least 4 hours after surgery, then sent back to the animal center. Three days later, we take out the LI and L5 spinal, DRG and anterior nerve samples of the rabbits, make the cryo-slices immediately. Within the followed 12 hours we measured the fluorescence associated ADM on these different sites under fluorescence microscope. Described and evaluated the distinct expression within the three groups and different sites in each group, all the results and measurements are executed double-blinded.ResultsThe samples from DRG,AR and spinal are no big differencebetween the experiment and control groups under microscope. With the fluorescence microscope, we can find strong ADM associated fluorescence in all of the experiment groups, whereas the samples from control group almost nothing. Especially, the strong illumination was shown in the DRG but only on the membrane of the AR and spinal. Furthermore, although we can not find the site-difference among the different concentrations of ADM, the intensity of the signal does show dose-dependence: The strongest is in group 3, the signal in group 2 is stronger than that in group l.In addition, compared to the other groups, the spinal from group3 has shown scattering spot-like fluorescence.DiscussionThe stubborn nerve pain(SNP) is still a clinical dilemma till now, since the DRG can accept, convey and regulate all kinds of the insulted sense of the body, it plays a pivotal role in the therapy of SNP. Initially, peoples thought about the resection of the dorsal root and DRG. Although the latter is theoretical better than former, both of them are the invasive therapy with the severe complement. In addition,the damage of the motor nerve caused by neurolytic block with ethanol and phenol also limited the dissemination of this therapy in the pain clinic. Recently, Kato s executed the selective-, retrograde-, sense nerve ganglia chemi-resection with ADM successfully. This is one of the most effective and safety innovate therapy to the SNP till now, with the minimal invasive and high-selection to the sense nerve ganglia as well. The drug injected by PVB can enter the epidural through the intervertebral foramina, block the nerve root in the same side, rather than the bilateral block as EB. Thus root nerve pain can take advantage of the PVB due to the more concentrated drugs in the puncture sites. It is well-used to the clinical PHN and cancer pain by the cervical and thoracic PVB with ADM, but the basic mechanism is still unclear. With the present study, the strong illumination only can be found inside the DRG, on the membrane of AR and spinal as well, but not in the spinal and AR. It seems almost all of the drugs entered into the DRG through the PVB with ADM, thereby we conclude the ADM has a high, site-selective effection to DRG. But the exactly reason for this phenomenon remains further investigation. There are several explanations: the number of non-myelin sheath... |
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