Objective

2

To explore the effects of electroacupuncture (EA) on microglial activation in the lumbar spinal cord and the ultrastructure of intervertebral disc nucleus pulposus cells in rabbits with lumbar intervertebral disc degeneration (LIDD).

Methods

2

Twenty-four SPF-grade healthy male New Zealand rabbits were randomly divided into a control group

a sham operation group

a degeneration group

and an EA group

with 6 rabbits in each group. The degeneration group and the EA group were treated with annulus fibrosus injury method to establish LIDD models. The EA group was treated with EA intervention at bilateral L

4

and

L

5

Jiaji (EX-B2) points

with disperse-dense wave

frequency in 2 Hz/15 Hz

20 min each time

once daily

with 6 consecutive days followed by 1 day of rest

for 4 weeks. Gait function and Pfirrmann grading scores were compared among groups. Immunohistochemistry was used to detect positive expression of the microglial markers Oxford 42 (OX42) and cyclooxygenase-2 (COX2) in the dorsal horn of the lumbar spinal cord. ELISA was used to detect the levels of inflammatory factors (tumor necrosis factor-α [TNF-α

]

interleukin [IL

]

-1β

IL-6

and IL-10) in the lumbar spinal cord. Transmission electron microscopy was used to observe the ultrastructure of nucleus pulposus cells of lumbar intervertebral discs. Western blot was used to detect protein expression of aggrecan and collagen Ⅱ in the nucleus pulposus of lumbar intervertebral discs in each group.

Results

2

Compared with the control group

there were no statistically significant differences in gait function score

Pfirrmann grading score

mean optical density values of OX42 and COX2 in the dorsal horn of the lumbar spinal cord

levels of TNF-α

IL-1β

IL-6

and IL-10 in the lumbar spinal cord

and protein expression of aggrecan and collagen Ⅱ in the nucleus pulposus of lumbar intervertebral discs in the sham operation group(

P

>

0.05). Compared with the sham operation group

the degeneration group showed decreased gait function score (

P

<

0.05)and increased Pfirrmann grading score (

P

<

0.05); the mean optical density values of OX42 and COX2 in the dorsal horn of the lumbar spinal cord were increased (

P

<

0.05); the levels of TNF-α

IL-1β

and IL-6 in the lumbar spinal cord were increased (

P

<

0.05)

while the level of IL-10 was decreased (

P

<

0.05); nucleus pulposus cells of lumbar intervertebral discs showed irregular cell membranes

nuclear pyknosis

cytoplasmic condensation

decreased organelles in the cytoplasm

and mi

tochondrial swelling or vacuolization; protein expression of aggrecan and collagen Ⅱ in the nucleus pulposus of lumbar intervertebral discs was decreased (

P

<

0.05). Compared with the degeneration group

the EA group showed increased gait function score (

P

<

0.05) and decreased Pfirrmann grading score (

P

<

0.05); the mean optical density values of OX42 and COX2 in the dorsal horn of the lumbar spinal cord were decreased (

P

<

0.05); the levels of TNF-α

IL-1β

and IL-6 in the lumbar spinal cord were decreased (

P

<

0.05)

while the level of IL-10 was increased (

P

<

0.05); irregular cell membranes

nuclear pyknosis

and cytoplasmic condensation of nucleus pulposus cells of lumbar intervertebral discs were obviously improved

cytoplasmic organelles were relatively complete

and mitochondria showed mild swelling;protein expression of aggrecan and collagen Ⅱ in the nucleus pulposus of lumbar intervertebral discs was increased(

P

<

0.05).

Conclusion

2

EA may alleviate intervertebral disc degeneration by inhibiting microglial activation and its inflammatory response in the lumbar spinal cord of LIDD model rabbits

and improving the ultrastructure of intervertebral disc nucleus pulposus cells.