Early electroacupuncture intervention delays progression of disease in mice with amyotrophic lateral sclerosis by down-regulating TLR4/NF-κB signaling

Abstract

To observe the effect of early electroacupuncture (EA) intervention on Toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) signaling pathway in mice with amyotrophic lateral sclerosis (ALS), so as to explore its mechanisms underlying alleviation of ALS. Fifty-four ALS (ALS-SOD1G93A) mice with SOD1G93A gene mutation identified by PCR were randomly divided into model group, 60 day(d) EA group and 90 d EA group(n=18 mice in each group), and other 18 ALS-SOD1G93A negative mice were used as the control group. At the age of 60 and 90 days, mice of the two EA groups received EA (2 Hz, 1 mA) stimulation of bilateral "Jiaji" (EX-B2) of L1-L2 and L5-L6 for 20 min, twice a week for 4 weeks,respectively. When being 60 days old, the mice in the model and control groups were subjected to the same binding as that in the two EA groups but without EA intervention. The tail suspension test was used to judge the onset time of disease and the survival period, and rotary rod fatigue test was used to evaluate the hind limb motor function. Nissl staining method was used to observe the content of Nissl bodies in the anterior horn of the lumbar spinal cord. Immunohistochemical staining was used to observe the expression of ionized calcium binding adaptor molecule-1 (Iba-1) in the anterior horn of the lumbar spinal cord, and Western blot was used to detect the relative expression of TLR4, NF-κB and tumor necrosis factor-α (TNF-α) in the lumbar spinal cord. The disease onset time apparently delayed in the 60 d EA group than in the model group (P<0.01). The survival time was apparently shorter in the model group than in the control group (P<0.01), and obviously prolonged in the 60 d EA and 90 d EA groups than in the model group (P<0.01). The rotatory rod time was obviously shorter in the model group than in the control group (P<0.05), and apparently longer in the 60 d EA group than in the model group and 90 d EA group (P<0.05). Compared with the control group, the model group had a decrease in the number of Nissl bodies in the anterior horn of the lumbar spinal cord (P<0.01), and an increase in the expression levels of Iba-1, TLR4, NF-κB and TNF-α in the lumbar spinal cord (P<0.01). In contrast to the model group, both 60 d EA and 90 d EA groups had an apparent increase in the number of Nissl bodies and a marked decrease in the expression levels of Iba-1, TLR4, NF-κB and TNF-α in the lumbar spinal cord (P<0.05, P<0.01). The therapeutic effects of 60 d EA group were evidently superior to those of 90 d EA group in delaying the onset time of disease, prolonging the survival time and rotatory rod time, increasing the number of Nissl bodies, and in down-regulating the expression of Iba-1, TLR4, NF-κB and TNF-α (P<0.05, P<0.01). The early intervention of EX-B2 EA is more effective in delaying the progression of ALS than post-onset intervention in ALS-SOD1G93A mice, which may be related to its functions in inhibiting the excessive activation of microglia, and down-regulating TLR4/NF-κB signaling.