Hypothesis

Low-intensity nociceptive activity functions as a hormetic signal that preserves METTL3/14 expression and m6A RNA methylation in aging neurons; chronic pharmacological suppression of pain erodes this protective input, accelerating m6A decline and neuronal proteostasis collapse.

Mechanistic Rationale

Pain perception activates TRPV1-expressing sensory neurons, leading to calcium influx and activation of CaMKII. CaMKII can phosphorylate METTL3, enhancing its catalytic activity and stability (see [1] for METTL3 dependence in synaptic transcripts). Simultaneously, subthreshold nociceptive firing stimulates the p38 MAPK/MSK1 pathway, resulting in CREB phosphorylation and increased transcription of the METTL3/14 genes. Low‑level reactive oxygen species generated during nociceptive signaling activate NRF2, which binds antioxidant response elements in the METTL3 promoter, further boosting expression. These convergent pathways create a feed‑forward loop where basal pain signaling sustains the m6A machinery that, in turn, methylates transcripts encoding proteostasis regulators (e.g., HSP70, BAG3) and synaptic proteins, thereby maintaining folding capacity and reducing misfolded load.

When analgesics such as NSAIDs or opioids blunt this input, the downstream kinases are less activated, METTL3 phosphorylation drops, and its protein half‑life shortens. The resulting reduction in m6A methylation preferentially affects transcripts with low basal methylation, including many synaptic and stress‑response genes, reproducing the hypomethylation pattern observed in aged and AD brains ([1],[2]). Loss of m6A diminishes the efficiency of mRNA export and translation, weakening the compensatory upregulation of chaperones and autophagy components that normally counteract age‑related protein misfolding ([3],[4]). Thus, analgesic‑induced silence of nociceptive signaling removes a physiological cue that keeps the m6A‑proteostasis axis tuned for resilience.

Testable Predictions

• In 20‑month‑old mice, daily low‑dose capsaicin (0.1 mg/kg, i.p.) for 3 months will yield higher METTL3 protein levels and greater global m6A (measured by m6A‑ELISA) in hippocampal lysates compared with vehicle‑treated age‑matched controls.
• Chronic ibuprofen administration (50 mg/kg/day, chow) over the same period will reduce METTL3 phosphorylation (p‑METTL3) and decrease m6A enrichment on CAMK2A and GLUA1 transcripts (m6A‑RIP‑qPCR).
• These molecular shifts will correlate with increased insoluble tau and ubiquitinated protein aggregates, diminished LC3‑II conversion, and impaired performance on the Morris water maze.
• Neuron‑specific TRPV1 knockout mice will exhibit the same m6A loss and proteostatic decline seen with ibuprofen treatment, whereas viral overexpression of TRPV1 in the hippocampus will rescue METTL3 levels and m6A despite analgesic exposure.
• Survival analysis will show that capsaicin‑treated aged mice have a ~15 % increase in median lifespan and improved grip strength and frailty scores relative to ibuprofen‑treated cohorts.
• In human cerebrospinal fluid from older adults, self‑reported frequent NSAID use will associate with lower CSF m6A‑modified synaptic RNA signatures, after adjusting for age and neurodegeneration biomarkers.

Each prediction is falsifiable: a null result (no difference in METTL3/m6A between pain‑stimulated and analgesic‑treated groups) would refute the hypothesized causal link between nociceptive signaling and the m6A‑proteostasis maintenance axis.