Effect of electroacupuncture on expression of autophagy-related proteins in nucleus pulposus of cervical spondylosis rabbits.

Abstract

Objectives: To observe the effects of electroacupuncture (EA) on the morphological changes of intervertebral disc tissues, apoptosis of nucleus pulposus cells, and the protein expression of Unc-51 like autophagy-activated kinase 1 (ULK1), homologous series of yeast Atg6 (Beclin1), and light chain protease complication 3 type (LC3) in nucleus pulposus tissue of cervical spondylosis rabbits, so as to explore the role of cellular autophagy in EA treatment of cervical spondylosis.

Methods: A total of 24 New Zealand white rabbits were randomly divided into blank, model and EA groups, with 8 rabbits in each group. In the EA group, both sides of the cervical (C)3-C6 "Jiaji" (EX-B2) were stimulated by EA (2 Hz/100 Hz, 1 mA) for 25 min, once daily for 5 days in a course, with a 2-day interval between courses, totaling 4 treatment courses. X-ray was used to assess cervical spine radiographic changes and evaluate radiographic scores；transmission electron microscopy was used to observe ultrastructural changes in nucleus pulposus cells；HE staining was used to observe morphological changes of intervertebral disc tissues and conduct pathological scoring；TUNEL staining was used to observe apoptosis rate of nucleus pulposus cells；Western blot was performed to detect protein expression levels of ULK1, Beclin1, and LC3 in nucleus pulposus tissue.

Results: Compared with the blank group, rabbits in the model group showed significantly higher cervical spine radiographic scores (P<0.01), higher pathological scores of intervertebral disc tissues (P<0.05), increased apoptosis rate of nucleus pulposus cells (P<0.01), and decreased expression levels of ULK1, Beclin1, and LC3Ⅱ proteins in nucleus pulposus tissue (P<0.05). Compared with the model group, the EA group showed significantly lower pathological scores of intervertebral discs (P<0.05), lower apoptosis rate of nucleus pulposus cells (P<0.01), and higher protein expression levels of ULK1, Beclin1, and LC3Ⅱ in nucleus pulposus tissue (P<0.01). Rabbits in the blank control group exhibited generally normal organelle structures in nucleus pulposus tissues with few autophagic vacuoles, indicative of early stages of autophagy；while those in the model group showed disrupted organelle structures with cytoplasmic condensation and those in the EA group exhibited autophagosomes with double-membrane structures in nucleus pulposus tissues.

Conclusions: EA promotes the expression of ULK1, Beclin1, and LC3Ⅱ proteins in nucleus pulposus tissues, reduces apoptosis of nucleus pulposus cells, and improves intervertebral disc degeneration.