Sex-specific longitudinal reversal of aging in old frail mice (Irina Conboy)

#1

Be aware that in the study below they are using the unusual approach to lifespan increase calculated on “remaining lifespan”, which is very different from the typical ITP approach of calculating it on total lifespan.

Male mice receiving a combination of OT + A5i experienced:

  • A 73% life extension from the point of treatment.
  • A 14% boost in overall median lifespan.

From: Irina M Conboy

Sent: Wednesday, August 27, 2025 2:30 PM
Subject: Living longer and in a healthier state even when starting as old and frail

Hello everybody,

Our very recent paper on life-span and health-span extension by defined pharmacology is linked for your perusal Sex-specific longitudinal reversal of aging in old frail mice | Aging

One of the most intriguing findings, in my view, is that it works excellently for males (better than anything published thus far) and not at all for females.

Cheers,

Irina Conboy, PhD

Sex-specific longitudinal reversal of aging in old frail mice

Important studies report acute rejuvenation of mammalian cells and tissues by blood heterochronicity, old plasma dilution, defined factors, and partial reprogramming. And extension of rodent lifespan via single-prong methods was tried in recent years. Here, we examined whether simultaneous calibration of pathways that change with aging in opposite directions would be more effective in increasing healthspan and lifespan. Moreover, we started with the challenging age group - frail 25-months-old mice that are equivalent to ~75-year-old people. We used an Alk5 inhibitor (A5i) of the age-elevated, pro-fibrotic transforming growth factor-beta (TGF-β) pathway that regulates inflammatory factors, including IL-11, and oxytocin (OT) that is diminished with age and controls tissue homeostasis via G-protein-coupled receptor and ERK signaling. Treatment of old frail male mice with OT+A5i resulted in a remarkable 73% life extension from that time, and a 14% increase in the overall median lifespan. Further, these animals had significantly increased healthspan, with improved physical performance, endurance, short term memory, and resilience to mortality. Intriguingly, these benefits manifested only in the male and not in the female mice, yet OT+A5i had positive effects on fertility of middle-aged female mice. Mechanistically, the bio-orthogonal metabolic proteomics on the blood serum demonstrated that the acute, 7-day, treatment of the old mice with OT+A5i youthfully restored systemic signaling determinants and reduced protein noise in old mice of both sexes. However, after 4 months of OT+A5i, only old male, but not female, mice remained responsive, showing the youthful normalization of systemic proteome. These findings establish the significant health-span extension capacity of OT+A5i and emphasize the differences in aging and in response to longevity therapeutics between the sexes.

Open access paper:

AI Summary:

Here’s a detailed and structured summary and analysis of the paper “Sex-specific longitudinal reversal of aging in old frail mice” published online on August 21, 2025 in Aging (Albany NY) (Aging-US).

Summary

Scope & Rationale

  • The study investigates whether combining interventions that move aging-related pathways in opposite directions yields superior results in promoting healthspan and lifespan, compared to single-pronged methods.
  • It focuses on frail mice aged 25 months, roughly equivalent to 75-year-old humans (Aging-US)—a particularly challenging and clinically relevant demographic.

Interventions Employed

  1. Alk5 inhibitor (A5i): Targets the elevated TGF-β (Transforming Growth Factor-beta) pathway, which is pro-fibrotic and linked to inflammation (e.g., IL-11 regulation).
  2. Oxytocin (OT): A hormone that declines with age, important for tissue homeostasis via G-protein-coupled receptor and ERK signaling pathways (Aging-US).

Key Findings

Lifespan & Healthspan (Males)

  • Male mice receiving a combination of OT + A5i experienced:
    • A 73% life extension from the point of treatment.
    • A 14% boost in overall median lifespan.
    • Notable improvements in physical performance, endurance, short-term memory, and mortality resilience(Aging-US).

Sex-Specific Effects

  • These pronounced benefits were absent in female mice.
  • However, in middle-aged female mice, OT + A5i enhanced fertility (Aging-US).

Systemic Proteomic Effects

  • A short, 7-day treatment in both sexes restored youthful systemic signaling and reduced “protein noise” in serum.
  • At the 4-month mark, only males maintained youthful normalization of the serum proteome; in females, responsiveness waned (Aging-US).

Mechanistic Insight

  • The combined treatment appears to recalibrate aging-related signaling pathways in the male systemic proteome, leading to functional rejuvenation.
  • Short-term gains were seen across both sexes, but sustained long-term benefits were male-specific (Aging-US).

Analysis & Perspective

Strengths

  • Clinically relevant model: Using frail, aged mice strengthens translational relevance.
  • Multi-pronged strategy: Targeting pathways that diverge with age (i.e., restoring diminished signals while inhibiting elevated ones) is strategic and innovative.
  • Measuring both lifespan and functional healthspan offers more holistic insight.
  • Sex-specific evaluation highlights crucial differences in therapeutic response—a valuable insight often overlooked.

Limitations and Considerations

  • Lack of long-term female benefit: The discrepancy between sexes raises questions about underlying biology and requires exploration.
  • Translational challenges: Whether these results can be replicated in humans remains unknown.
  • Safety: Long-term effects on other systems (e.g., cancer risk, fibrosis) need careful assessment.

Implications & Future Directions

  • Evidences that combination therapies might have enhanced potency in reversing aging markers.
  • Personalized gerotherapeutics may require sex-specific designs.
  • Encourages deeper exploration into why female physiology responds differently, which might involve hormonal cycles, receptor expression, or immune function.
  • Opens the door to testing similar combinatorial interventions in other aging models or possibly early phase human studies.

Contextual Integration

  • This study complements research showing that epigenetic rejuvenation—for example, via Yamanaka factors or chemical cocktails—can reverse aging signatures at the cellular level (Aging-US).
  • However, Kato et al. focus on systemic, organismal outcomes (lifespan, physical and cognitive performance), marking a significant leap toward translational aging therapeutics.

Conclusion

The paper presents compelling evidence that a dual-intervention with oxytocin and ALK5 inhibitor can substantially reverse aging and extend lifespan in frail aged male mice, with systemic rejuvenation confirmed via proteomic analysis. The sex-specific outcomes underscore the importance of tailoring anti-aging therapies to biological differences and signal a move toward more nuanced, effective geroscience treatments.

Let me know if you’d like to dive deeper into specific data—such as survival curves, behavioral assays, proteomic profiles—or explore comparisons with similar longevity interventions.

Citation for reference formatting:

Kato C, Zheng J, Quang C, Siopack S, Cruz J, Robinson ZR, Fong N, Zhang ZA, Young P, Conboy MJ, Conboy IM. Sex-specific longitudinal reversal of aging in old frail mice. Aging (Albany NY). 2025 Aug 21; [Epub ahead of print] (Aging-US).

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#2

Love my Oxytocin nasal spray :slight_smile:

I appears there are more than 1 Alk5 inhibitor (A5i)…

Advances in the discovery of activin receptor-like kinase 5 (ALK5) inhibitors

https://www.sciencedirect.com/science/article/abs/pii/S0045206824002372

Oxytocin_health_benefits.pdf (41.5 KB)

3 Likes
#3

I think I’ll give it a go. I’m finding Oxytocin Nasal Spray 100 units/ml, 10ml @ $168 available from US pharmacy. What dose are you using, Steve?

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#4

I take 4 to 6 sprays a day. Each spray delivers 25mcg = 17iu of Oxytocin. First 2 sprays in the morning before my shake. One or 2 more during the day and 2 just before bed.

Most spray bottles deliver approximately 12 units of volume per spray

Oxytocin is/should be dirt cheap if you buy it in bulk powder.

Here is my method.

Oxytocin is dosed in IU (international units). IU’s are not to be confused with the Units marked on an insulin syringe. 10 units = 0.10 mL liquid - this is NOT IU’s

10 IU of oxytocin is equivalent to 17 mcg or micrograms (μg) or 0.017 milligrams (mg) of Oxytocin. The desired “low dose” is 15 IU or approximately 25 mcg of Oxytocin

To produce a nasal spray with 25mcg (micro grams) or 15 IU per spray of Oxytocin, add 5mg of Oxytocin to 24mL of distilled water, each 0.12 ml of solution contains 0.25mg of Oxytocin. Each spray will deliver approximately 0.12 mL liquid (12 units of volume)

This will provide 200 doses. If you use 4 per day, it should last for 50 days. I would not pay more than $40 for that.

These are the spray bottles we use,

2 Likes
#5

Since the “standard” for nasal spray devices is about 0.12mL per spray,

EDIT TO CORRECT MY BAD MATH @Phillipe

1mL / 0.12mL per spray = 8.3 spray per 1mL
1mL = 100iu / 8.3 spray = 12i.u per spray = dose
1 bottle - 10ml x 8.3 sprays = 83 doses of 12 i.u. Oxytocin

So this is not a bad dose, just expensive at $168 / 83 = $2.00 per single dose. If you take 4 per day you get 20 days per bottle.

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#6

I wonder if they looked at ovariectimized female mice, ie mice that with their ovaries removed. Little known mouse biological fact : they don’t go through menopause. I don’t think they used any ovariectimized in this study, which is too bad. It’s entirely possible that we would see the same degree of reversal in male and ovariectimized female mice.

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#7

I see peptide suppliers listing lipholyzed oxytocin powdered form as “synthetic.” Is that what is commonly used?

#8

You only need lyophilized if you are going to inject it.

For nasal sprays and sublingual use that is not necessary,

Pretty much all hormones are synthetic. All that means is that it doesn’t come from a “natural” source like your hypothalamus and released by the pituitary gland.

#9

Is oxytocin the big target here, or is it TGF beta? Or perhaps IL 11? This intervention in a signaling pathway changed a bunch of things, but only produced good results in males. We have several drugs that affect TGF beta favorably such as Telmisartan.

1 Like
#10

Matt Kaeberlein on X:

Some of you may have seen the new study titled “Sex-specific longitudinal reversal of aging in old frail mice” that reports oxytocin + Alk5 inhibitor, started at 25 months of age, increased lifespan and healthspan metrics in mice.

I think this is an interesting study with some valuable insights. That said, it also highlights how spin and hype can undermine credibility in the aging field.

Before the hype gets too far ahead of the data, here’s some context:

•Aging was not reversed. This is an unfortunate overreach in the title. Improving late-life health is important, but that is not the same thing as reversing aging. IMHO, there is really no excuse for allowing these kinds of claims in the peer-reviewed literature at this point. It just makes the field appear unserious and not rigorous.

•The mice were not frail. The title and abstract imply that the study was performed on frail mice, but that is not the case. They were standard 25-month-old C57BL/6 animals, which corresponds very roughly to 70-year-old humans. We wouldn’t refer to a generic population of 70-year-olds as “frail”. Some individuals at that age are frail, most are not.

•Healthspan was not shown to be significantly increased. Claims of “significantly increased healthspan” in the abstract are not valid. There is no consensus single metric for measuring healthspan, and it is impossible to detect a “significant increase” in something for which there is no quantitative method for measurement.

The authors attempted to make up their own definition of healthspan and measure it, but in science one group does not get to arbitrarily make up definitions for established terms. This again makes the field appear unserious and not rigorous.

A few healthspan metrics were shown to be statistically significantly improved. The vast majority of healthspan metrics were not measured in this study.

•Other interventions have shown greater and broader effects on both lifespan and healthspan metrics when started at similar or later ages. That doesn’t mean this paper isn’t important or valuable, or that this therapy couldn’t achieve better results if applied differently, but it does reduce broader impact.

For perspective, the median lifespan benefit reported here is roughly 2/3 what’s been observed for just 3 months of rapamycin treatment starting at 20 months (see graphic). It’s much less than that for maximum lifespan. It’s less than half the effect of 50-60% caloric restriction. The claimed “73% extension” is an artifact of late life onset and short-lived controls.

Some things I liked:

•Combinatorial approach: Combined oxytocin (age-declining factor) with Alk5 inhibitor (blocking age-elevated TGF-β signaling) is novel and makes sense. Both are very interesting targets from a translational (human biology) perspective

•Partial molecular rejuvenation: Acute treatment restored some of the systemic youthful proteomic signatures and reduced protein noise (a proposed biomarker of aging). This is an interesting angle to be explored further with additional multi-omic approaches.

•Clinically relevant agents: Oxytocin is already FDA-approved; Alk5 inhibitors (like Vactosertib) are in human trials. Suggests a plausible path toward translation

Overall, a valuable addition to the literature that extends prior work from the same group, but precision in language and careful communication are essential if the field is to advance responsibly and gain credibility among the broader scientific community. Authors, reviewers, and editors need to to better.

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Source: https://x.com/mkaeberlein/status/1962897969851854978

5 Likes
#11

AND! Oxytocin (available at Walmart) “contributes to fidelity in men by enhancing their female partner’s attractiveness.” Who knew? :joy:

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#12

This is really interesting. I did a bit of digging. There’s a talk with Irina and Michael Conboy where they discuss Oxytocin, but they also mention that taking it intranasally wouldn’t have a strong enough effect systemically.

But, there was a really interesting study in mice where they feed them L. reuteri and they saw a marked increase in Oxytocin production and saw improved wound healing.

It might be easier and cheaper to order a probiotic - though, it’s hard to test.

There’s a link to a brand which is the same strain.

2 Likes
#13

I saw Irina Conway at the Vitalist bay conference the other month. I sat down with her to learn more about what she’s up to these days. As part of her company she said that they are working on some new compounds targeting aging. I get the feeling it’s likely related closely with her research so it seems likely it may be targeting these same pathways. She said they were going into clinical trials soon, if I recall.

2 Likes
#14

Very cool. Their lab is doing some really interesting work. I’ll try and make it up to next one if happens. Do they have a disease indication?

#15

Good question, on disease identification. She was in the middle of eating lunch when I sat down beside her so I didn’t ask as many questions as I wanted. We’ll have to wait and see. Or ask her the next time someone sees her. She’s a regular attendant in Bay Area longevity science meetings.

1 Like