| Part I Histological Effects of High Intensity Focused Ultrasound on Rat Sciatic NerveObjective:The research aims at establishing the experimental base of the use of High Intensity Focused Ultrasound (HIFU) in the fields of peripheral nerve by observing the pathologic reactions of rat sciatic nerves after the exposure of HIFU.Methods:Forty eight healthy male SD rats were randomly divided into six groups (8 in each group)based on the exposure time:radiation of 10 seconds,30 seconds,1 minute,2 minutes,3 minutes and 4 minutes.The target area treated by HIFU radiation was the middle portion 0.5 cm behind the greater trochanter of left femur and the surrounding within 1 cm of the middle portion (Positioning is according to diagnostic ultrasound and direct vision). After the test, the 1 cm sciatic nerve in the target area were fixed and the changes in its histomorphology were observed (4 sciatic nerve of rats were randomly selected and stained by H&E and Masson's trichrome for light microscopy, the other 4 sciatic nerve of rats were observed by transmission electron microscope).The corresponding region of the right sciatic nerve served as the control.Results:Untreated section of right sciatic nerve showed normal morphology.10-s FU-treated nerve section had no obvious pathologic changes; 30-s and 1-min FU-treated nerve section showed minor lesion; 2-min FU-treated nerve section showed serious lesion; 3-min and 4-min FU-treated nerve section showed considerably serious lesion.Conclusions:The experiment shows that nervous tissue may suffer partial or total damage, or even irreversible necrosis under the exposure of HIFU with different doses.There fore, HIFU is expected to be a novel treatment for chronic neuropathic pain. Part II Alleviating effect on chronic neuropathic pain by HIFUObjective:This research aims to explore the therapeutic efficacy and mechanism of High Intensity Focused Ultrasound (HIFU) in alleviating chronic neuropathic pain so as to establish the experimental base of the use of HIFU alleviating chronic neuropathic pain.The research is conducted by investigating the expression of astrocyte glial fibrillary acidic protein(GFAP)in cornu dorsale medullae spinalis and the content of substance p (SP) andβ-endorphin (β-EP) in hematoplasma of rats with chronic sciatic nerve pain.Methods:Sixty healthy male SD rats were randomly divided into two groups:10 as sham operated group and the other 50 as CCI models induced by tying off sciatic nerve.10 days later, the rats in the CCI model group were again randomly divided into 5 subgroups (10 in each group):CCI model group,10-s HIFU-treated sciatic nerve group,30-s HIFU-treated sciatic nerve group,1-min HIFU-treated sciatic nerve group, and 2-min HIFU-treated sciatic nerve group. The target area treated by HIFU radiation was the proximal part of sciatic nerve ligation department (titanium clip positioning).4 days later, the rats were anesthetized,2 ml of blood was taken, pleuron was perfused, L4-L6 spinal cord was taken. Sham operation group and model group remained untreated. The content of sp and (3-EP in hematoplasma of rats was detected by ELISA method and changes in the content of GFAP in cornu dorsale medullae spinalis of rats were detected and analyzed by immumofluorescence method combined with graphic image analysis software.Results:(1) The expression of GFAP in L4-L6 cornu dorsale medullae spinalis was strong in the CCI model group.The content of SP in plasma decrease while that ofβ-EP increased; (2) Compared with sham operated group, The expression of GFAP (P<0.01) and the content of SP (P<0.05) were higher in the CCI model group.However, the content ofβ-EP decreased (P<0.01); (3) Compared with CCI model group, The expression of GFAP and the content of SP andβ-EP in 10-s HIFU-treated sciatic nerve group were not significantly different (P>0.05); (4) Compared with CCI model group, The expression of GFAP and the content of SP were lower in 30-s and 1-min HIFU-treated sciatic nerve groups (P<0.01) However, the content ofβ-EP increased (P<0.05); (5) Compared with CCI model group, The expression of GFAP and the content of SP andβ-EP in 2-min HIFU-treated sciatic nerve group were not significantly different (P>0.05)Conclusion:HIFU can alleviate neuropathic pain under appropriate intensity. The possible underlying mechanism of pain alleviation might be to block nerve conduction, obstruct the conduction of pain signals, inhibit chronic neuropathic pain in spinal cord astrocytes(the expression of GFAP decreased),and change the content of pain neurotransmitter in blood (the content of algesic substance SP decreased, analgesic substanceβ-EP increased)... |
PDF Full Text Request