Spinal manipulative therapy promotes nucleus pulposus resorption and alleviates pain in a rat model of lumbar disc herniation via JNK-dependent regulation of inflammation and tissue remodeling.

Researchers investigated whether spinal manipulation therapy (a hands-on technique similar to chiropractic adjustment) could help the body naturally heal herniated discs in the lower back. When a disc herniates, the soft inner material (nucleus pulposus) can press on nerves, causing severe pain and sciatica. While the body can sometimes reabsorb this material on its own, scientists wanted to know if spinal manipulation could speed up this healing process.

Using a rat model of lumbar disc herniation, researchers compared three groups: animals receiving spinal manipulation every other day, those receiving steroid injections weekly, and untreated controls. They measured pain responses and examined the herniated tissue over 28 days, looking at inflammation markers, tissue breakdown, and nerve healing.

The spinal manipulation group showed remarkable results. Pain relief began by day 3 and continued improving throughout the study. By day 28, the herniated disc material was almost completely reabsorbed—better results than even the steroid group achieved. The key difference was how spinal manipulation worked: rather than simply suppressing all inflammation like steroids do, it maintained a balanced healing environment that allowed beneficial immune cells to clear away damaged tissue while protecting healthy cells and promoting new blood vessel growth.

The researchers identified a specific molecular pathway (JNK signaling) as essential for these benefits. When they blocked this pathway, spinal manipulation lost its effectiveness.

While this study used manual spinal manipulation rather than acupuncture, it provides important insights into how hands-on therapies may promote natural healing in disc problems. Patients considering treatment for herniated discs should consult qualified practitioners experienced in integrative approaches to spinal health.

This animal study examined spinal manipulative therapy (SMT) effects on nucleus pulposus resorption in lumbar disc herniation. Researchers used autologous NP implantation onto L5 nerve roots in rats, comparing SMT (every other day), epidural betamethasone (weekly), and sham treatment over 28 days (n values not specified).

SMT significantly reduced mechanical allodynia from day 3 and achieved near-complete NP resorption by day 28, outperforming corticosteroid treatment. Mechanistically, SMT selectively modulated inflammation rather than broadly suppressing it—moderately elevating TNF-α, IL-1β, VEGF, and MMP-3 to facilitate macrophage recruitment, neovascularization, and matrix remodeling while reducing apoptosis via Bax/Bcl-2 regulation. SMT inhibited NF-κB and MAPK (p38, ERK, JNK) phosphorylation pathways.

Crucially, all SMT benefits were abolished in JNK2-knockout mice, confirming JNK-dependent mechanisms. Clinical relevance: Manual therapy may promote disc resorption through balanced immunomodulation rather than simple anti-inflammatory suppression, suggesting potential advantages over corticosteroid monotherapy for LDH management.