N-acetylcarnosine attenuates age-associated declines in multi-organ systems to improve survival (BioRxiv)

#1

https://www.biorxiv.org/content/10.1101/2025.08.19.671148v3

Histidine containing dipeptides (HCDs) such as N-acetylcarnosine are endogenous metabolites that are ergogenic and mitigate metabolic dysfunction. We previously demonstrated that short-term N-acetylcarnosine treatment is highly efficacious in protecting muscle atrophy induced by disuse. Here we demonstrate that a 6-months treatment of N-acetylcarnosine attenuates a broad spectrum of age-associated maladies and improved survival by ~50% in female mice. A comprehensive survey of organ systems revealed that N-acetylcarnosine prevents decline in adiposity, diastolic function, vasodilation, muscle strength, and bone density. Together, N-acetylcarnosine substantially delays the onset of system-wide end-stage pathology to prolong lifespan. As an endogenously present metabolite, treatment with N-acetylcarnosine may be a safe and promising intervention to promote healthy aging in humans.

CGPT Summary and analysis:

Here’s a concise, evidence-based read of the uploaded preprint, with links and inline citations to the PDF.

Paper at a glance

Title: N-acetylcarnosine attenuates age-associated declines in multi-organ systems to improve survival

Preprint: bioRxiv (posted Oct 30, 2025) — link

Model: Aged C57BL/6 mice, intervention from 18→24 months. Drinking water was supplemented with N-acetylcarnosine (NACAR) at 80 mM, pH-adjusted to 7.5, refreshed weekly; testing was blinded for repeated measures.

What they did

  • Ran a 6-month supplementation in late-life mice and phenotyped multiple systems (metabolic, neuro-endocrine, cardiovascular, renal, musculoskeletal), then tissue biochemistry/LC-MS.

Key findings

  • Survival: At ~24 months, female NACAR mice showed ~50% higher survival (≈75% vs ≈50% in vehicle); no survival effect in males by study end.
  • Body composition & metabolism (females): Fat mass preserved (greater gWAT), lower energy expenditure and reduced activity; RER fell (more fat oxidation). No group differences in glucose tolerance.
  • Vascular biology: Endothelium-dependent dilation (ACh) was similar between groups, but L-NMMA suppressed vasorelaxation more in NACAR, yielding higher calculated NO bioavailability (i.e., greater eNOS contribution).
  • Cardiac function: No change in cardiac output or EF; fractional shortening was lower in NACAR females (interpretation: similar forward flow with less forceful contraction; possible lower afterload). Diastolic indices largely unchanged in females; E/e’ improved in males.
  • Skeletal muscle: Ex vivo force increased (EDL & soleus) in females, without clear in-vivo functional gains (treadmill, rotarod, grip).
  • Bone: Distal femur trabecular number and bone volume fraction increased (both sexes). Tibial trabecular bone and knee OA scores unchanged.
  • Kidney: No differences in kidney weight, histology, urine output, creatinine clearance, or GFR.
  • Biochemistry: NACAR enriched in tissues (greater in females for muscle/heart/gWAT) and lower protein carbonyls in several tissues.
  • Mechanistic framing: Authors emphasize carbonyl scavenging (e.g., 4-HNE) and note human translatability because N-acetylcarnosine is resistant to human CN1 , unlike carnosine.

What’s novel

  1. Long-term HCD intervention in aging per se: Authors state no prior study has tested long-term histidine-containing dipeptide (HCD) supplementation during aging itself with multi-organ phenotyping.
  2. Sex-specific survival benefit with coordinated shifts in adiposity, muscle force, vascular NO bioavailability, and bone density (prominent in females).
  3. Mechanistic translatability rationale: Selecting NACAR (vs carnosine) because it’s not hydrolyzed by human CN1 .

Critique (strengths & limitations)

Strengths

  • Late-life start (18 → 24 mo) with broad systems profiling and blinded functional testing.
  • Biochemical confirmation of exposure (tissue NACAR levels) and reduced protein carbonyls .
  • Clear, sex-aware reporting (female-biased tissue enrichment and phenotypes).

Limitations / questions

  • Preprint (not peer-reviewed).
  • Survival analysis windowed: improvement is shown by ~24 months; not a full lifespan curve to death for all cohorts, so effects on median/maximum lifespan remain unresolved.
  • Dose & delivery: 80 mM in water is high; human PK/PD and tolerability at any equivalent exposure are unknown. (Authors position NACAR as more translatable than carnosine due to CN1, but no human dosing datahere.)
  • Cardiac results mixed: unchanged CO/EF, lower fractional shortening in females (interpretation offered, but blood pressure wasn’t measured to validate “lower afterload”).
  • In-vivo function: despite ex vivo muscle strength gains, treadmill/rotarod/grip were not improved — important for translational relevance.
  • Mechanism inference : Higher “NO bioavailability” is calculated indirectly from L-NMMA shifts; arterial dilation at baseline was unchanged , so systemic hemodynamic impact remains speculative without in-vivo BP.
  • Multiplicity/statistics: Many endpoints across systems raise false-positive risk; the paper reports standard tests (ANOVA/t-tests), but a pre-registered primary endpoint or FDR plan isn’t evident in the PDF excerpts.
  • External validity: Initiation at 18 months means earlier aging trajectories (e.g., earlier cardiac decline) may have been missed.

Takeaways for translation

  • Signal in females : coordinated preservation of fat reserves , muscle contractility , vascular NO contribution , and femur trabecular bone , with better survival by 24 mo . Mechanistic link to carbonyl scavenging is plausible but not proven causal here.
  • Human logic: NACAR’s resistance to human carnosinase (CN1) is the central translational argument; human PK, dosing, and safety will be the gating issues for trials.

Useful links

  • Preprint main page: bioRxiv
  • PDF (uploaded): methods/results and figures cited throughout (see inline citations above).

Bottom line

Promising female-specific late-life survival benefit with multi-organ functional signals after 6 months of N-acetylcarnosine in aged mice — mechanistically consistent with carbonyl stress mitigation and improved eNOS contribution, but with mixed cardiac and in-vivo functional readouts, no BP data, and no full lifespan curves. Human feasibility hinges on PK/PD and dosing; a small, sex-stratified Phase 1/2 focusing on vascular, muscle, and bone endpoints would be a logical next step.