Effect Of Different Functions Of Sympathetic Nerve On Chronically Compressed Peripheral Nerve

Part I Effect of different functions of sympathetic nerve on chronically compressed peripheral nerveSympathetic nerve belongs to autonomic nerve system. Anatomically, the postganglionic fiber of sympathetic nerve is a component of peripheral nerve. Under a normal physiological condition, directly anatomical connection seldom exists between peripheral nerve and sympathetic nerve system, and peripheral afferent nerves and their terminal receptors are also seldom affected by sympathetic nerve (Janig & Koltzenburg, 1991). However, under pathologic conditions, such as peripheral chronic compressive injury, sympathetic nerve is involved in the development and maintenance of neuropathologic pain via insulting the blood supply of peripheral nerve or developing sympathetic-sensory coupling by sympathetic sprouting due to nerve growth factor or neurotrophic factor which are produced by Wallarian degeneration. Recent experiment research showed that sympathetic nerve blockage promoted regeneration of peripheral nerve when acutely transected, while excision of sympathetic nerve was harmful to peripheral nerve regeneration, which indicates that the effect of sympathetic nerve on the regeneration of acutely injuried peripheral nerve may have something to do with the different functions of sympathetic nerve. Recently, studies on the relationship between sympathetic nerve and peripheral nerve focus on chronic pain and regeneration of peripheral nerve acutely injuried. Then, whether the effect of sympathetic nerve on the injury degree of chronically compressed peripheral nerve and on the function recovery of the peripheral nerve after decompression? And is the effect related to the function state of sympathetic nerve? There still is no literature concerned these issues.The experiments are performed to investigate the effects of different functions of sympathetic nerve on the lesion degree of chronically compressed peripheral nerve and on the recovery of peripheral nerve functions after decompression.Experiment I Effect of different functions of sympathetic nerve on the lesion degree of peripheral nerve chronically compressed Materials1. experimental animals:thirty-two Sprague-Dawley male rats weighted 200g were offered by experimental animal department of Fudan university.2. Main reagents:Trizol reagent(invitrogen), RevertAid First Strand cDNA Kit(Fermentas), FastStart Universal SYBR Green Master(ROX)(Roche), Primers of substance P, S100b and GAPDH were synthesized by Shanghai Sangon Biological Engineering Technology & Services Co.3. laboratory apparatus:portable tissue tearor(biospec),4℃centrifuge, ultraviolet spectrometer, Opticon-2 PCR instrument, Leica FW4000 image analysis system, Medtronic electromyography.MethodsThirty-two rats were divided into three experimental groups (A1, B1,C1) and a normal control group(D group), each group had 8 rats. A mid-anterocervical approach was applied to expose the lower trunk of left brachial plexus which was experimental side. A model of the lower trunk chronic compression was made according to the rat model of sciatic nerve compression designed by Mackinnon. The left middle cervical ganglions of rats in group C1 were resected when the compression models were made. The middle cervical ganglions of the rats in group B1 were blocked once a day for one month with 0.5ml of 0.25% bupivacaine, starting from two months after surgery for model. The lower trunk nerves were decompressed three months after making models. And then, CMAP of the first interosseus was tested by electrograph to record latency and amplitude. Myelinated nerve fibers of the distal part of the compressed lower trunk were analyzed. The expression level of S100b mRNA of the distal part of the compressed nerve and that of substance P mRNA of C8T1 dorsal root ganglion were detected by RT-PCR.Results1. The mean latencies of CMAP of first interosseus (A1>B1>C1>D) were (4.8±0.9)ms,(4.3±0.6)ms,(3.9±0.5)ms,(2.8±0.2)ms, respectively. The difference of latencies among group A1, B1 and C1 was significant (P P=0.047). The mean amplitudes of CMAP(A1B1>C1) was (8.05±3.47)×10-3,(5.95±2.51)×10-3,(2.69±0.92)×10-3, respectively, with a significant difference among them. The expression levels of S100b mRNA of group A,, B, and C, were distinctively higher than that of control group D, the level of which was (0.52±0.15)×10-3.4. The relative expression levels(A1>B1>C1) of SP mRNA of C8T1DRG were (3.62±0.83)×10-2, (2.95±0.72)×10-2, (2.24±0.73)×10-2, respectively, among which the difference was significant (P=0.006). All of them were more than that of normal control group D, which was (1.21±0.28)×10-2。Conclusions1. Besides mechanical compression, sympathetic nerve plays an important role in developing of diseases of peripheral nerve compression.2. The effect of sympathetic nerve on the development of peripheral nerve compression is related to the function state of sympathetic nerve, which means the higher excitation of sympathetic nerve, the more pain caused by compression and the more serious lesion of the nerve fibers. To inhibit or remove the effect of unhealthy sympathetic nerve can help to reduce lesion degree of peripheral nerve chronic compression.3. The overexpressed SP and S100b may be the mediators by which sympathetic nerve participate in the development of peripheral nerve chronic compressive diseases.ExperimentⅡEffect of different functions of sympathetic nerve on the function recovery of compressed peripheral nerve after decompression Materials1. experimental animals:Twenty-four Sprague-Dawley male rats weighted 200g were offered by experimental animal department of Fudan university.2. Main reagents:Trizol reagent(invitrogen), RevertAid First Strand cDNA Kit(Fermentas),FastStart Universal SYBR Green Master(ROX)(Roche), Primers of substance P, S100b and GAPDH were synthesized by Shanghai Sangon Biological Engineering Technology & Services Co.3. laboratory apparatus:portable tissue tearor(biospec),4℃centrifuge, ultraviolet spectrometer, Opticon-2 PCR instrument, Leica FW4000 image analysis system, Medtronic electromyography.MethodsTwenty-four rats were divided into three experimental groups of A2, B2, and C2. Each group had 8 rats. A mid-anterocervical approach was applied to expose the lower trunk of left brachial plexus which was experimental side. A model of the lower trunk chronic compression was made according to the rat model of sciatic nerve compression designed by Mackinnon. Three months after compression surgery, the rats of group A2 were decompressed without interfering the middle cervical ganglions and were bred for another month. The rats of group B2 were decompressed, then left middle cervical ganglions were blocked with 0.5ml of 0.25% bupicaine once a day for one month. The middle cervical ganglions of group C2 were resected when decompressed and continued to be breed for one month. One month after decompression, CMAP of the first interosseus was tested by electrograph to record latency and amplitude. Myelinated nerve fibers of the distal part of the compressed lower trunk were analyzed. The expression level of S100b mRNA of the distal part of the compressed nerve and that of substance P mRNA of C8T1 dorsal root ganglion were detected by RT-PCR.Results1. The mean latencies of CMAP of first interosseus (A2>B2>C2) were (3.8±0.6) ms,(3.6±0.4) ms,(3.2±0.3) ms, respectively. The difference of latencies among group A2, B2 and C2. The mean amplitudes of CMAP(A2 B2>C2) was (5.39±1.19)×10-3,(1.76±0.32)×10-3, (1.03±0.39)×10-3, respectively, with a significant difference(P=0.001) among them. The expression levels of S100b mRNA of group A2, B2 and C2 were still distinctively higher than normal level that was (0.52±0.15)×10-3.4. The relative expression levels (A2>B2>C2) of SP mRNA of C8T1 DRG were (3.16±1.03)×10-2,(2.36±0.68)×10-2,(1.49±0.80)×10-2, respectively, among which the difference was significant(P=0.003).Conclusions1. During the couse of treating compression diseases, besides removing mechanical compression, decreasing the excitation of abnormal sympathetic nerve does good to alleviating pain, regeneration and function recovery of compressed peripheral nerve when decompressed.2. The lower function of unhealthy sympathetic nerve, the better recovery of peripheral nerve.3. The effect of sympathetic nerve on the pain relieving,nerve regeneration and function recovery of peripheral nerve may via reducing substance P and S100b protein which mediate inflammatory response, so as to maintain a good physiological condition.PartⅡImproved clinical detection of sympathetic nerve functionSympathetic skin response(SSR) is a non-invasive, simple and reliable means of the clinical detection of sympathetic function. the most commonly used test site is palm, and the most commonly used stimulation method is electrical stimulation. However, SSR recorded on palm can reflect the sympathetic efferent function of a single neural pathway such as median nerve or ulnar nerve,therefore, the record site was changed appropriately. The absolutely dominated positions of ulnar and median nerves were taken for the detection sites. SSR characteristics of absolutely dominated area were analyzed and the normal reference values were established.Subjects and methods1. subjects1) 60 healthy volunteers, including 31 males and 29 females, aged 18 to 54 years old, mean age 32.4 years.30 were detected in the right side, the other 30 were detected in the left side.2) Ulnar nerve injury in 10 cases, including 6 males and 4 females, average age of 32.3 years. The right side in 7 cases, left in 3 cases, the injury time within 3 months.3) Complete median nerve injury in 10 cases,7 males and 3 females, average age of 35.1 years. The right side injury in 5 cases, left in 5 cases, the injury time within 3 months.4) Both median nerve and ulnar nerve injury in 3 cases,2 males and 1 female, average age 28 years, are part of the wrist injury, injury time 1 month or less.2. methods1) detection site:the palm, pulp of index finger and little finger.2) Conditions require:room temperature, light, quiet environment, participants relax, skin temperature keeps 32～36℃.3) Equipment:electromyograph.4) Detection methods:contralateral median nerve was stimulated by DC square wave 0.2ms with a current strength of 10-30Am. A surface electrode was used to record the latency and amplitude of SSR.Results1. SSR test results of right and left hands:The difference of the latency and amplitude of SSR tested on palms, index finger pulps and little finger pulps between right and left hands was not significant (P> 0.05).2. Gender and SSR test results:the average latency of SSR recorded on palms, index finger pulps and little finger pulps was longer in men than in women, but the difference was not statistically significant. The mean amplitude was higher in men than in women.3. SSR latencies recorded on palms, index finger and little finger pulps of healthy volunteers were (1.38±0.15) s,(1.54±0.22) s,(1.59±0.23) s, respectively, and the amplitudes of which were (3.78±2.37) mv (2.26±1.52) mv,(2.46±1.84) mv, respectively. The latencies of SSR recorded on index and little finger pulps were longer than on palm, and amplitudes of SSR were lower on index and little finger pulps than on palm. These difference were statistically significant (latency:P< 0.01, amplitude:P<0.01). But the difference of latency and amplitude of SSR between index finger and little finger pulps was not significant (P>0.05).4. when median nerve injuried, SSR of the absolutely dominated region (index finger pulp) disappeared, and the latency of SSR recorded on palm was slightly longer, compared with the normal, the difference was not statistically significant, but the amplitude became much lower (P=0.000), and SSR of the little finger pulp was not affected. while ulnar nerve injuried, SSR of the absolutely dominated region (small finger pulp)disappeared without significant effect on SSR of palm, and SSR of index finger pulp was not affected. when both median nerve and ulnar nerve were injuried, then SSR of any part of the palm disappeared.5. Normal reference value of SSR:SSR of palm:latency≤1.69s and amplitude:0～8.52mv;SSR of index and small finger pulps:latency≤2.00s and amplitude:0～5.73mv.Conclusions1. SSR on both palm and finger pulps can be detected. Compared with SSR of the palm site, the latency of the SSR of finger pulps is longer and the amplitude is lower. there is no statistical difference between SSR of right and left hand. The amplitude of SSR of female is lower than that of male.2. latency is a stable indicator for its stability, while amplitude serves as reference because of its large variability. Overlong latency is abnormal and disappeared amplitude is also abnormal. Whether a high amplitude is abnormal, the latency should be taken into account.3. Palm area innervated by sympathetic nerve which comes from both ulnar and mdian nerve pathways. however, the absolutely dominated region have no cross innervation. Therefore, SSR recorded from the absolutely dominated regions (index and little finger pulps) may reflect the function of sympathetic nerve from a single neural pathway (ulnar nerve or median nerve).