Preclinical transcriptomic study

The identification of new roles for nicotinamide mononucleotide after spinal cord injury in mice: an RNA-seq and global gene expression study

Chunjia Zhang et al. · Frontiers in Cellular Neuroscience · 2023

Evidence type: Preclinical mechanistic study Interpretive weight: Mechanistic contextResearch area: Spinal cord injury and neuroinflammation
DesignPreclinical mouse contusion spinal-cord-injury study with 7-day NMN treatment, behavioral testing, tissue NAD+ measurement, RNA sequencing, pathway analysis, protein-interaction analysis, and qRT-PCR validation.
PopulationMice with moderate-to-severe contusion spinal cord injury; no human participants.
SampleMultiple mouse groups and molecular assays were used; sample sizes varied by experiment as reported in the publication.
InterventionNMN 500 mg/kg body weight per day by intraperitoneal injection, starting immediately after spinal cord injury and continuing for seven days; saline served as control.
EndpointsSpinal-cord NAD+ levels; Motor-function recovery; Pain-related behavior; RNA-seq global gene-expression changes; Inflammation-related pathways including IL-17, TNF, Toll-like receptor, NOD-like receptor, and chemokine signaling; qRT-PCR validation of inflammatory factors and chemokines

What the publication reported

This study tested NMN after a moderate-to-severe spinal cord contusion injury in mice. NMN was injected daily for seven days beginning immediately after injury.

The authors reported that spinal-cord NAD+ fell after injury and was restored by NMN. NMN-treated mice also showed better motor-function recovery and less pain-related behavior in the reported model.

RNA sequencing and qRT-PCR suggested broad suppression of inflammatory signaling, including IL-17, TNF, Toll-like receptor, NOD-like receptor, and chemokine pathways. These are preclinical trauma findings and do not establish treatment benefit in people with spinal cord injury.

Key findings

  • Spinal-cord NAD+ levels decreased after injury and were increased by NMN supplementation.
  • NMN-treated mice showed improved motor-function recovery in the reported injury model.
  • Pain-related behavior was reduced in NMN-treated mice.
  • RNA-seq identified inflammation-related pathways as major NMN-responsive signatures after injury.
  • Inflammatory factors including IL-1β, TNF-α, IL-17A, and IRF7 and chemokines including CCL3 and CXCL10 were reduced in validation experiments.
  • The study identified Hmox1 and SIRT2 among NAD+-linked genes altered after injury and treatment.

What it cannot establish

  • The study used an acute mouse contusion model, not human spinal cord injury.
  • NMN was administered intraperitoneally at 500 mg/kg/day, which is not comparable to routine oral supplementation.
  • Treatment started immediately after injury, limiting relevance to delayed clinical treatment.
  • RNA-seq pathway associations do not by themselves prove which pathway causes the functional effect.
  • The seven-day treatment period does not establish long-term neurological safety or efficacy.
HealthspanX claim boundary: This study does not establish that NMN treats spinal cord injury, improves neurological recovery, or relieves pain in humans.

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