Acupuncture Sciatic Nerve Neuroprotective Mechanism Found
Acupuncture Sciatic Nerve Neuroprotective Mechanism Found
Liaoning University of Traditional Chinese Medicine researchers conclude that acupuncture inhibits nerve cell death due to sciatic nerve impairment. A controlled laboratory investigation identified the neuroprotective role of two acupuncture techniques for impaired sciatic nerves. Shallow acupuncture and deep acupuncture at Huantiao (GB30) successfully promoted motor functional recovery, improved nerve conduction velocity, and boosted regeneration of sciatic nerve cells.
The results are confirmed by multiple parameters (e.g., sciatic nerve function index, motor nerve conduction velocity, microscopic observation). In addition, shallow acupuncture and deep acupuncture resulted in reduced nerve cell death while upregulating the level of phosphatidylinositol 3-kinase (PI3K) and protein kinase B (PKB) in the dorsal root ganglion. The researchers note, “shallow and deep acupuncture techniques play a neuroprotective role by activating the PI3K-PKB signaling pathway and up-regulating PI3K and PKB levels.” 
Forty-eight SD rats were randomly divided into four groups: a control group, a model group, a deep acupuncture group, and a shallow acupuncture group (n=12 in each group). The sciatic nerve injury model in this investigation was established by suturing a silicone tube around the sciatic nerve. After 14 days of modeling, the sciatic nerve function index and motor nerve conduction velocity significantly decreased compared with the control group. The acupuncture group had less nerve cell death numbers and levels of PI3K and PKB significantly increased.
The researchers provide a brief synopsis of the Traditional Chinese Medicine (TCM) understanding of sciatic nerve impairment. In Traditional Chinese Medicine, sciatic nerve impairment falls under the Bi Zheng (impediment) or Wei Zheng (wilting) class of disorders. According to TCM theory, either shallow or deep acupuncture applied to acupoint GB30 (Huantiao) is indicated for sciatic nerve impairment. Huantiao is located on the foot shaoyang gallbladder meridian. GB30 (Huantiao) is indicated for lower back pain, lower limb pain, and impediment of the lower limbs. Deep anatomical structures of Huantiao include the gluteus maximus, piriformis, and sciatic nerve trunk.
Acupuncture successfully inhibited cell death in the impaired sciatic nerve by regulating PI3K and PKB levels. The researchers note, “Both shallow and deep acupuncture reversed pathological changes of impaired nerve cells and inhibited nerve cell death.” Microscopic observation shows that there were less Schwann cells, Wallerian degeneration, and axonal and myelin breakdown after receiving shallow or deep acupuncture.
Schwann cells promote phagocytosis of damaged nerves.  Wallerian degeneration is a process of degeneration that occurs when a nerve fiber is injured.  New growth of nerve cells was found in the shallow and deep acupuncture groups. The researchers also note that “shallow and deep acupuncture significantly increased PI3k and PKB protein levels compared with the model group.” In addition, “Although both acupuncture techniques produced positive outcomes, deep acupuncture had the most significant results.”
Yan et al. provide insight into the importance of their findings. They note that the PI3K-PKB signal transduction pathway plays an important role in inhibiting nerve cell death. Nerve cell injury or death can activate PI3K. Consequently, activated PI3K is able to activate other downstream effector molecules through phosphorylation, including PKB. PKB, in turn, inhibits nerve cell death by increasing the expression of antiapoptotic Bcl-1 and Bcl-2. The researchers conclude that the activation of the PI3K/PKB pathway exerts a neuroprotective role through inhibiting cell apoptosis in sciatic nerve impairment.
Treatment commenced on the 15th day of modeling. For the deep acupuncture group, an acupuncture needle was inserted into GB30, reaching as deep as 8mm. High-frequency ultrasound imaging technology was used to ensure that the needle was placed at the sciatic nerve trunk in the deep acupuncture group. For the shallow acupuncture group, an acupuncture needle was inserted into GB30, reaching a depth of 3–5 mm. The needle was inserted into the muscle level and did not reach the nerve level in the shallow acupuncture group (confirmed by high-frequency ultrasound imaging results). After needle insertion, an SDZ-II electroacupuncture device was connected to the needles for 20 minutes. The acupuncture session was conducted daily, for 14 consecutive days. The researchers note that in a human clinical setting, a 50 mm needle is often used. An appropriate depth of needle insertion results in a deqi sensation (soreness, numbness, fullness, tingling).
Evaluations were performed before and after acupuncture treatment. First, the sciatic function index (SFI) was calculated using the footprint parameters of the rats. SFI calculation uses a formula developed by Mackinnon et al.  SFI is used to evaluate the motor function recovery of the sciatic nerve. An SFI of 0 means normal nerve function whereas an SFI of -100 is complete impairment of the sciatic nerve.
The motor nerve conduction velocity (MNCV) was tested. MNCV is used to measure the electrical conduction ability of the motor nerves. In addition, pathological changes of the sciatic nerve as well as death cell numbers were obtained though microscopic observations. Protein levels of PI3K and PKB were also determined. PI3K is a family of lipid kinases, which plays key regulatory roles in modulating cell growth and survival.  PKB is a signaling protein kinase that plays a key role in regulation of metabolism, cell survival, and motility. 
Following acupuncture treatment, SFI, MNCV, and the number of living cells were increased in both deep and shallow acupuncture groups compared with the model group. PI3K and PKB levels were significantly upregulated in the deep and shallow acupuncture groups. The deep acupuncture group produced better outcomes that the shallow acupuncture group in downregulating cell death numbers and in upregulating SFI, MNCV, and PI3K and PKB protein levels on day 28 of modeling.
The results of the aforementioned research indicate that acupuncture is an effective treatment modality for sciatic nerve impairment. Researchers demonstrate that acupuncture improves motor function and conduction velocity of the sciatic nerve while inhibiting nerve cell death by regulating pathways responsible for providing neuroprotective effects.
 Yan HC, Ma TM, Tao X, Ma XD. Anti-apoptotic Mechanism of Deep Electroacupuncture at “Huantiao” (GB 30) in Repair of the Injured Sciatic Nerve in Rats [J]. Acupuncture Research, 2018(11):711-717.
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