Electroacupuncture attenuates intervertebral disc degeneration by upregulating aquaporins via the cAMP/PKA pathway.

Abstract

Intervertebral disc degeneration (IVDD) is characterized by a decrease in extracellular matrix (ECM) and water loss, which is a major cause of low back pain (LBP). Electroacupuncture (EA) has long been used to relieve LBP in IVDD. To investigate whether EA can upregulate aquaporins (AQPs) in IVDD via the cAMP/PKA pathway in a rabbit model of disc degeneration. A homemade loading device was adapted to trigger a disc degeneration model. After 28 days, EA treatment was performed. Magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI), and diffusion tensor imaging (DTI) were performed to evaluate AQP content and water diffusion. AQP protein expression in the slices was observed by Western blot and immunofluorescence (IF) staining. The pathology of the intervertebral discs was determined by staining. cAMP and PKA levels were examined using ELISA, and the expression of AQP genes as well as the cAMP/PKA pathway and its related molecules were examined using quantitative reverse transcription-PCR (qRT-PCR) and Western blot analysis. The EA intervention reduced MRI Pfirrmann scores, fractional anisotropy (FA), and apparent diffusion coefficient (ADC) values. EA can upregulate the expression of AQP1 and AQP3, thereby improving the pathological morphology of the nucleus pulposus (NP) and the cartilage endplate of the intervertebral disc. cAMP and PKA levels were significantly increased after EA intervention in rabbits with IVDD. EA intervention can partially improve the expression of related molecules in the cAMP/PKA pathway, but H-89 reverses the effect of EA. EA can attenuate intervertebral disc degeneration by regulating AQP expression, a process that may be mediated by the cAMP/PKA pathway.