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[69.67.186.35]) by mx.google.com with ESMTPS id d75a77b69052e-5100da47e0bsi5416161cf.35.2026.04.27.15.03.47 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Apr 2026 15:03:48 -0700 (PDT) Received-SPF: pass (google.com: domain of bounces+tjphuhs=gmail.com@bh.mail.beehiiv.com designates 69.67.186.35 as permitted sender) client-ip=69.67.186.35; Authentication-Results: mx.google.com; dkim=pass header.i=@bhmta.beehiiv.com header.s=bh header.b=l9WnDcTc; dkim=pass header.i=@mail.beehiiv.com header.s=bh header.b=y1kV8gQ1; spf=pass (google.com: domain of bounces+tjphuhs=gmail.com@bh.mail.beehiiv.com designates 69.67.186.35 as permitted sender) smtp.mailfrom="bounces+tjphuhs=gmail.com@bh.mail.beehiiv.com"; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=beehiiv.com X-BmtaRef: eyJfQF8iOiJcXF8vIiwicmVjaXBpZW50IjoidGpwaHVoc0BnbWFpbC5jb20iLCJ4X2xpc3RfaWQiOiJmZDQxNjMwZS1lOTFmLTQ2ZDktYTI3NC1iNzQwZGFiNzU2ZDIiLCJ4X3N1YnNjcmliZXJfaWQiOiI5YzQwZDYzOS02ZTFkLTQyOTItYTlkNy0wZTRjYmJiNWQ1ZGIifQ== DKIM-Signature: v=1; a=rsa-sha256; d=bhmta.beehiiv.com; s=bh; c=relaxed/relaxed; bh=0n5cYczAubsePjnhNQBmhsQRF/UJMHKx78wJ52xpzAo=; h=from:subject:mime-version:content-type:content-transfer-encoding: list-unsubcribe:feedback-id:list-unsubscribe-post:reply-to:to:cc: content-type:feedback-id:from:subject:to; t=1777327427; b=l9WnDcTcFyFkHSvJ90TyntMKzqy77on6V6auFCCprlfnuZ1Ap36nvTDTZ9kV0TShJ92UL9rxk qBIjOCzGD6vZSmejV0PWfC5MIu1rjHbLRvIKsqQaejCNk9OXI7O7Ko+24ko/+kR4Q4q+vBo4peo E29bs9C73asPAF1SnhCa6GFYInmSXpEofMQdUB48xweBkARgfoGtDxO8g25jeDFNaMYfvoho5Tk 8CxMzmJYn7nzWwQvwC4rzjL3dU4QZ2M8DOO3WMzzdaPSn24TV60e1hy0M5JJI79ixiAteaqfQye vMq+FznHBGzPJuFGykqevI5uCP9RcSG1GpTcao4Awfig==; DKIM-Signature: v=1; a=rsa-sha256; d=mail.beehiiv.com; s=bh; c=relaxed/relaxed; bh=0n5cYczAubsePjnhNQBmhsQRF/UJMHKx78wJ52xpzAo=; h=from:subject:mime-version:content-type:content-transfer-encoding: list-unsubcribe:feedback-id:list-unsubscribe-post:reply-to:to:cc: content-type:feedback-id:from:subject:to; t=1777327427; b=y1kV8gQ1lPJWtZfdH2L3J0QrqErV6I+wy46hIKGBhSZGsV0T94XI5emptYE6Go+pohvVWetNn aIAf4Ibc9jglQwvDSGTTbbYekevgBNAI24fbGMM7/nk/CD8O0//zprTIhse69PikI2UUOrp4pXJ eSXDVzo5rmBNT3c7l1xJMvj7Tr9uvEfxbio4ChQ3522GKUN+Te8LN6vZaq9L5GZ3fzDg94lqECE X/ryEoa1fTxDmAGiFeLRFfRjZ22ZYuZmtKZdn0ABp0V5ZV3TcVhkaY6Bu0KKV391X9uK6EQ9Or6 kqf3zNVE+a2/IZNN+FoGtpR8ZjdEfe4S5669LOAgXhPw==; Received: from mail.beehiiv.com by bhmta(mta31) with HTTP id for ; Mon, 27 Apr 2026 22:03:47 +0000 Content-Type: multipart/alternative; boundary="KeBlNxJ3SKWeBuktUEA8HA" To: "tjphuhs@gmail.com" Feedback-ID: 82821342-b4b2-4973-bf03-1b193373f834:newsletter:fd41630e-e91f-46d9-a274-b740dab756d2:c8f61fda6a60803 From: Hunter Williams List-Unsubscribe: , List-Unsubscribe-Post: List-Unsubscribe=One-Click Reply-To: =?utf-8?Q?Hunter=27s_Health_Hacks?= Subject: GHK-Cu Beyond Beauty X-Batch-Id: 5d582daf-53b9-4dc5-b293-a16e1928dcd2 X-Subscriber-ID: 9c40d639-6e1d-4292-a9d7-0e4cbbb5d5db X-Subscription-ID: 663283104 sId: fd41630e-e91f-46d9-a274-b740dab756d2 x-beehiiv-ids: {"account_name":"https://huntershealthhacks.beehiiv.com/","campaign_id":"82821342-b4b2-4973-bf03-1b193373f834","category":"newsletter","email_generated_at":1777327426,"user_id":"fd41630e-e91f-46d9-a274-b740dab756d2"} x-beehiiv-type: newsletter x-list-id: fd41630e-e91f-46d9-a274-b740dab756d2 x-list-owner: x-newsletter: https://huntershealthhacks.beehiiv.com/p/ghk-cu-beyond-beauty x-newsletter-id: https://huntershealthhacks.beehiiv.com/ x-newsletter-signup: https://huntershealthhacks.beehiiv.com/subscribe Mime-Version: 1.0 Date: Mon, 27 Apr 2026 22:03:47 +0000 Message-ID: <20260427.220347.a7d2675b@mta31> --KeBlNxJ3SKWeBuktUEA8HA Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Happy Monday!=0A=0AMost people in the peptide world know GHK-Cu as a skin a= nd hair peptide. =0A=0ABut what if I told you that same peptide might be do= ing something far more interesting inside your brain?=0A=0AA new study just= dropped looking at GHK-Cu in aged mice. =0A=0AAnd the results are pushing = GHK-Cu out of the "beauty peptide" category and into something much bigger.= =0A=0AWe're talking measurable cognitive improvements and a transcriptiona= l signature that looks a lot like the gold-standard longevity drugs.=0A=0AY= ou can read the full preprint here: [https://www.biorxiv.org/content/10.648= 98/2026.04.09.717524v1](https://www.biorxiv.org/content/10.64898/2026.04.09= .717524v1)=0A=0ALet=E2=80=99s dig into what they found! =0A=0A=E2=80=9CIn c= ase you missed it, I launched a giveaway last week to celebrate 100,000 act= ive newsletter readers. You can register to [win here](https://hunterwillia= mshealth.com/giveaway). =0A=0A[https://hunterwilliamshealth.com/giveaway](h= ttps://hunterwilliamshealth.com/giveaway)=E2=80=9C =E2=80=94 =0A=0A=E2=80= =94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94= =E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80= =94=E2=80=94=0A=0A**The Study and How They Ran It**=0A=0AResearchers at the= University of Washington took 100 aged C57BL/6J mice, 50 male and 50 femal= e, all aged 20 to 21 months. =0A=0AIn mouse years, that's roughly equivalen= t to a human in their late 60s.=0A=0AThey split the mice into two groups ba= sed on the delivery method of GHK-Cu.=0A=0AGroup one got GHK-Cu by intraper= itoneal injection (IP), which is an injection into the abdominal cavity. Fi= ve days, once daily, 15 mg/kg.=0A=0AGroup two got GHK-Cu intranasally (IN).= Same dose, but sprayed into the nose once daily for eight weeks.=0A=0AThen= they ran the mice through something called the Box Maze, which is a spatia= l learning test. =0A=0AThe mouse has to find an escape tunnel in a brightly= lit box. =0A=0AFaster escape times across trials mean the mouse is learnin= g. =0A=0ALearning depends on the hippocampus, which is exactly the brain re= gion that takes a beating as we age.=0A=0AAfter behavioral testing, they pu= lled the hippocampi and ran immunohistochemistry plus bulk RNA sequencing t= o see what was happening at the molecular level.=0A=0A=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80= =94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94= =E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=0A= =0A**What They Found**=0A=0ABoth delivery methods improved learning. But th= e _quality_ of the improvement was very different.=0A=0AThe intranasal grou= p showed sustained improvement across trials 2, 3, and 4. Both males and fe= males got faster at finding the escape. The effect held.=0A=0AThe intraperi= toneal group? Males got a quick bump on trial 2, and then it faded. Females= got nothing.=0A=0ANow here's where it gets interesting.=0A=0AWhen they exa= mined the hippocampal tissue itself, intranasal mice showed increased synap= tophysin levels in females, a marker of synapse health. =0A=0ABoth sexes sh= owed reduced GFAP, a marker of brain inflammation and astrocyte activation.= =0A=0AThe RNA sequencing told an even bigger story. =0A=0AIntranasal GHK-Cu= suppressed mTOR signaling, MYC target genes, and oxidative phosphorylation= . =0A=0AThose are the exact same pathways that are suppressed by rapamycin = and caloric restriction, two of the most validated anti-aging interventions= .=0A=0AThe injection group activated DNA repair and stress-response pathway= s instead. =0A=0A=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80= =94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94= =E2=80=94=E2=80=94=E2=80=94=E2=80=94=0A=0A**Why the Routes Behaved So Diffe= rently**=0A=0AThis is the part that surprised me.=0A=0AIt comes down to two= things. Pharmacokinetics and exposure duration.=0A=0AWhen you inject GHK-C= u into the abdominal cavity, it absorbs fast and clears fast. The body sees= a quick spike, mounts a stress response, runs some repair programs, and th= en it's done. =0A=0AIntranasal delivery is a totally different beast. The n= ose has a direct line to the brain through the olfactory and trigeminal ner= ves. =0A=0AIt bypasses the blood-brain barrier entirely. =0A=0ASo when you = spray GHK-Cu daily for eight weeks, you're getting steady, sustained exposu= re right where you want it.=0A=0AThat's why intranasal looked like a longev= ity intervention, and IP looked like a healing peptide.=0A=0AThe route of a= dministration actually changed what GHK-Cu _did_.=0A=0ASame molecule, same = dose, two completely different outcomes depending on how you use it.=0A=0A= =E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80= =94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94= =E2=80=94=E2=80=94=0A=0A**What This Means **=0A=0AMost people in the biohac= king space are running GHK-Cu subcutaneously for skin, hair, and connective= tissue benefits. =0A=0ANothing wrong with that. It works. Taylor and I use= it all the time. =0A=0ABut this study suggests we might be leaving a massi= ve amount on the table.=0A=0AIf you're injecting GHK-Cu and hoping for cogn= itive or longevity benefits, you might not be getting them in any meaningfu= l way. =0A=0AThe injection route hits the body fast and clears fast. =0A=0A= Good for skin and tissue repair, but probably not much for your brain over = the long haul.=0A=0AIf brain health and cognitive aging are on your radar, = intranasal looks like the move. =0A=0AThe data here is mouse data, but the = mechanism makes sense. Direct nose to brain delivery. Sustained exposure. S= uppression of the same pathways that rapamycin hits.=0A=0AThis also reframe= s how we should think about GHK-Cu in general. =0A=0AIt's an endogenous tri= peptide that declines with age. It modulates inflammation, senescence pathw= ays, and, apparently, mitochondrial and growth signaling in the brain.=0A= =0A=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94= =E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80= =94=E2=80=94=E2=80=94=0A=0A**The Limitations**=0A=0AI'd be doing you a diss= ervice if I didn't flag the caveats.=0A=0AThis is a preprint. It hasn't bee= n peer reviewed yet. That doesn't mean it's wrong, but it means the work ha= sn't been formally vetted by other scientists.=0A=0AIt's a mouse study. Mou= se aging models translate reasonably well to humans for these pathways, but= 'reasonably well' isn't the same as 'guaranteed'.=0A=0AThey didn't measure= actual GHK-Cu concentrations in the brain. So we can't say for sure how mu= ch got there or how long it stayed.=0A=0AAnd they didn't include a young co= ntrol group, so we don't know whether GHK-Cu is restoring a youthful brain = state or creating something entirely new.=0A=0A=E2=80=94=E2=80=94=E2=80=94= =E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80= =94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=0A=0A**F= inal Thoughts**=0A=0AWe are barely scratching the surface of what peptides = do.=0A=0AIt's easy to chase the next sexy peptide. I get it. I do it too! = =0A=0ABut studies like this remind me that some of the peptides we already = have access to, the ones we think we understand, are doing far more than we= give them credit for. =0A=0AGHK-Cu has been around for decades. =0A=0AWe'v= e been using it for skin and hair for years. =0A=0AAnd here we are in 2026,= finding out it might also be one of the more interesting cognitive aging t= ools we have.=0A=0ASometimes the basics aren=E2=80=99t so basic after all.= =0A=0AKeep an open mind about the peptides already in your stack. They migh= t be quietly doing more than you think!=0A=0ABest, =0A=0AHunter Williams=0A= =0A=0A=E2=80=94=E2=80=94=E2=80=94=0A=0AYou are reading a plain text version= of this post. For the best experience, copy and paste this link in your br= owser to view the post online:=0Ahttps://huntershealthhacks.beehiiv.com/p/g= hk-cu-beyond-beauty --KeBlNxJ3SKWeBuktUEA8HA Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable GHK-Cu Beyond Beauty<= style>
New study on GHK-cu and the brain  ‌ = 204; ‌ ‌ ‌ ‌ ‌ = ‌ ‌ ‌ ‌ ‌ ‌= 60;‌ ‌ ‌ ‌ ‌ ‌=  ‌ ‌ ‌ ‌ ‌ R= 04; ‌ ‌ ‌ ‌ ‌ &= #8204; ‌ ‌ ‌ ‌ ‌= 0;‌ ‌ ‌ ‌ ‌ ‌&= #160;‌ ‌ ‌ ‌ ‌ ̴= 4; ‌ ‌ ‌ ‌ ‌ &#= 8204; ‌ ‌ ‌ ‌ ‌ = ;‌ ‌ ‌ ‌ ‌ ‌&#= 160;‌ ‌ ‌ ‌ ‌ ‌= ; ‌ ‌ ‌ ‌ ‌ = 204; ‌ ‌ ‌ ‌ ‌ = ‌ ‌ ‌ ‌ ‌ ‌= 60;‌ ‌ ‌ ‌ ‌ ‌=  ‌ ‌ ‌ ‌ ‌ R= 04; ‌ ‌ ‌ ‌ ‌ &= #8204; ‌ ‌ ‌ ‌ ‌= 0;‌ ‌ ‌ ‌ ‌ ‌&= #160;‌ ‌ ‌ ‌ ‌ ̴= 4; ‌ ‌ ‌ ‌ ‌ &#= 8204; ‌ ‌ ‌ ‌ ‌ = ;‌ ‌ ‌ ‌ ‌ ‌&#= 160;‌ ‌ ‌ ‌ ‌ ‌= ; ‌ ‌ ‌ ‌ ‌ = 204; ‌ ‌ ‌ ‌ ‌ = ‌ ‌ ‌ ‌ ‌ ‌= 60;‌ ‌ ‌ ‌ ‌ ‌=  ‌ ‌ ‌ ‌ ‌ R= 04; ‌ ‌ ‌ ‌ ‌ &= #8204; ‌ ‌ ‌ ‌ ‌= 0;‌ ‌ ‌ ‌ ‌ ‌&= #160;‌ ‌ ‌ ‌ ‌ ̴= 4; ‌ ‌
=

April 27, 2026   |  

GHK-Cu Beyond Beauty

N= ew study on GHK-cu and the brain

<= td align=3D"left" valign=3D"middle" class=3D"mob-stack">
<= /table>
 
3D"share
 
3D"share
 
3D"share
3D""
=
<= /tr>

Happy Monday!

Most people in the peptide world know GHK-Cu as a = skin and hair peptide.

But = what if I told you that same peptide might be doing something far more inte= resting inside your brain?

A new study just dropped looking at GHK-Cu in aged mice.

And the results are pushing GHK-Cu out of th= e "beauty peptide" category and into something much bigger.

We're talking measurable cog= nitive improvements and a transcriptional signature that looks a lot like t= he gold-standard longevity drugs.

You can read the full preprint here: https://www.biorxiv.org/content/10.64898/2026.04.0= 9.717524v1

Let=E2= =80=99s dig into what they found!

In case you missed it, I launched a giveaway last week to celebrate 100,0= 00 active newsletter readers. You can register to win here.

https://hunterwilliamshealth.com/giveaway

=
<= td class=3D"dd" align=3D"left" style=3D"padding:0px 15px;text-align:left;wo= rd-break:break-word;">

Both sexes showed reduced GFAP, a marker of brain in= flammation and astrocyte activation.

Those are the exact same pathways that are suppressed b= y rapamycin and caloric restriction, two of the most validated anti-aging i= nterventions.

<= tr>

It's an endogenous tripeptide that declines with ag= e. It modulates inflammation, senescence pathways, and, apparently, mitocho= ndrial and growth signaling in the brain.

<= td class=3D"dd" align=3D"left" style=3D"padding:0px 15px;text-align:left;wo= rd-break:break-word;">

This is a preprint. It hasn't been peer reviewed= yet. That doesn't mean it's wrong, but it means the work hasn'= t been formally vetted by other scientists.

=
 

The Study and How They Ran It<= /span>

Researchers at the Universit= y of Washington took 100 aged C57BL/6J mice, 50 male and 50 female, all age= d 20 to 21 months.

In mouse= years, that's roughly equivalent to a human in their late 60s.<= /p>

They split the mice into two groups= based on the delivery method of GHK-Cu.

Group one got GHK-Cu by intraperitoneal injection (IP), which= is an injection into the abdominal cavity. Five days, once daily, 15 mg/kg= .

Group two got GHK-Cu intra= nasally (IN). Same dose, but sprayed into the nose once daily for eight wee= ks.

Then they ran the mice t= hrough something called the Box Maze, which is a spatial learning test.

The mouse has to find an escap= e tunnel in a brightly lit box.

Faster escape times across trials mean the mouse is learning. <= /p>

Learning depends on the hippocampus= , which is exactly the brain region that takes a beating as we age.<= /p>

After behavioral testing, they pull= ed the hippocampi and ran immunohistochemistry plus bulk RNA sequencing to = see what was happening at the molecular level.

=
 

What = They Found

Both delivery= methods improved learning. But the quality of the improvemen= t was very different.

The in= tranasal group showed sustained improvement across trials 2, 3, and 4. Both= males and females got faster at finding the escape. The effect held.

The intraperitoneal group? Males = got a quick bump on trial 2, and then it faded. Females got nothing.=

Now here's where it gets inter= esting.

When they examined t= he hippocampal tissue itself, intranasal mice showed increased synaptophysi= n levels in females, a marker of synapse health.

The RNA sequencing told an even bigger story.

Intranasal GHK-Cu suppressed mTOR signaling, MY= C target genes, and oxidative phosphorylation.

The injection = group activated DNA repair and stress-response pathways instead.

 

Why the Routes Behaved So Differently

This is the part that surprised me.

<= /td>

It comes down to two things. Pharmacoki= netics and exposure duration.

When you inject GHK-Cu into the abdominal cavity, it absorbs fast and cle= ars fast. The body sees a quick spike, mounts a stress response, runs some = repair programs, and then it's done.

Intranasal delivery is a totally different beast. The nose ha= s a direct line to the brain through the olfactory and trigeminal nerves. <= /span>

It bypasses the blood-brain = barrier entirely.

So when = you spray GHK-Cu daily for eight weeks, you're getting steady, sustaine= d exposure right where you want it.

That's why intranasal looked like a longevity intervention, and= IP looked like a healing peptide.

The route of administration actually changed what GHK-Cu did.

Same molecule, same = dose, two completely different outcomes depending on how you use it.=

 

What This Means

Most people in the biohacking space are running GHK-Cu subcutaneo= usly for skin, hair, and connective tissue benefits.

Nothing wrong with that. It works. Taylor and I u= se it all the time.

But thi= s study suggests we might be leaving a massive amount on the table.<= /p>

If you're injecting GHK-Cu and = hoping for cognitive or longevity benefits, you might not be getting them i= n any meaningful way.

The i= njection route hits the body fast and clears fast.

Good for skin and tissue repair, but probably not m= uch for your brain over the long haul.

If brain health and cognitive aging are on your radar, intranasa= l looks like the move.

The = data here is mouse data, but the mechanism makes sense. Direct nose to brai= n delivery. Sustained exposure. Suppression of the same pathways that rapam= ycin hits.

This also reframe= s how we should think about GHK-Cu in general.

=  

The Limita= tions

I'd be doing y= ou a disservice if I didn't flag the caveats.

It's a mouse study. Mouse aging models translate reason= ably well to humans for these pathways, but 'reasonably well' isn&#= 39;t the same as 'guaranteed'.

They didn't measure actual GHK-Cu concentrations in the brai= n. So we can't say for sure how much got there or how long it stayed.

And they didn't include a= young control group, so we don't know whether GHK-Cu is restoring a yo= uthful brain state or creating something entirely new.

 

Final Thoughts

We ar= e barely scratching the surface of what peptides do.

It's easy to chase the next sexy peptide. I ge= t it. I do it too!

But stud= ies like this remind me that some of the peptides we already have access to= , the ones we think we understand, are doing far more than we give them cre= dit for.

GHK-Cu has been ar= ound for decades.

We'v= e been using it for skin and hair for years.

And here we are in 2026, finding out it might also be one= of the more interesting cognitive aging tools we have.

Sometimes the basics aren=E2=80=99t so basic af= ter all.

Keep an open mind a= bout the peptides already in your stack. They might be quietly doing more t= han you think!

Best, =

Hunter Williams

= = =
3D"ig"3D"yt"
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