Intracerebral hemorrhage is bleeding inside the brain tissue itself. Two rat studies from the same research group tested whether the GHK tripeptide, given by injection, could limit the damage that follows[1][2]. Both conclude that GHK may be a possible therapeutic strategy for the condition, so it is worth reading what each one did.
Three things frame everything below. The peptide was GHK without copper. The animals were rats. And the two studies differ on a point that is easy to miss: one gave GHK before the bleed, and the other gave it afterwards.
Key Takeaways
- Both studies used GHK without copper, injected into the abdominal cavity of male Wistar rats, in which a bleed was induced in the brain with the enzyme collagenase[1][2].
- The 2018 study gave GHK for three days before the injury. The 2020 study gave it for three days after, which is the more treatment-like design[1][2].
- In both, GHK-treated rats had less brain swelling, better scores on a neurological deficit scale and more surviving neurons than vehicle-treated rats[1][2].
- Follow-up ran to seven days, group sizes for each assay were 6 to 8 animals, and neither paper tested GHK-Cu, females, older animals or a human[1][2].
- We found no other study of GHK in brain hemorrhage, so the two papers are one group’s work and have not been independently repeated.
Why These Are Not GHK-Cu Studies
The titles and methods say GHK, glycine-histidine-lysine, and neither paper describes a copper complex[1][2]. This site is about GHK-Cu, and the difference is not trivial. The article on GHK without the copper explains why results for the bare peptide cannot be assumed to hold for the copper complex, or the reverse.
A cell or animal result on copper-free GHK says something about the tripeptide sequence. It does not say what a GHK-Cu serum, injection or supplement would do. When a product page cites these two papers for a copper peptide, that is a step the papers themselves did not take.
The 2018 Study: Treatment Before the Bleed
Seventy-two male Wistar rats weighing 250 to 280 g were divided into three groups of 24[1]. All three groups had a hemorrhage induced by stereotactic injection of bacterial collagenase type VII into the brain. One group received a vehicle injection, and the other two received GHK at 1 or 10 mg/kg into the abdominal cavity[1].
The GHK was given every 24 hours for three days, and the paper says it was given prior to the collagenase[1]. That is a pretreatment design. It asks whether having the peptide on board makes a bleed less damaging, which is a different question from whether the peptide helps after a bleed has happened.
In each group, eight rats were used for brain water content at 72 hours, eight for histology and eight for neurological deficit scoring at 4, 24, 72 and 168 hours[1]. There was no sham surgery group in the design described. The paper reports that GHK reduced brain water content, improved neurological deficit scores, reduced caspase-3 staining, increased the number of surviving neurons on Nissl staining and reduced cell death on a TUNEL assay[1].
The 2020 Study: Treatment After the Bleed
The 2020 study used 120 male Wistar rats in five groups of 24: a sham group, a vehicle-treated hemorrhage group and three GHK groups at 1, 5 and 10 µg/g[2]. A microgram per gram is the same as a milligram per kilogram. The GHK was injected into the abdominal cavity every 24 hours for three days after the collagenase was given[2].
The abstract does not say whether dosing came before or after the injury, but the methods do, and it is after[2]. The paper does not state how soon after the collagenase the first injection was given. Within each group, six rats went to each assay: brain water content, histology, neurological scoring through day seven, and biochemical analysis[2].
The abstract credits the 5 and 10 µg/g doses with better neurological recovery, less brain water and better neuron survival, and the figure legend places the neurological benefit at 3 and 7 days[2]. The 1 µg/g group is not credited with those effects. GHK also lowered TNF-alpha and IL-1 beta, two inflammatory signals, in tissue around the bleed[2].
What “Neurological Deficit” Meant
The behavioral measure in the 2020 study was a five-point scale based on circling. Rats were graded from 0, no circling, to 4, always circling, at 3 and 7 days[2]. The 2018 study used a five-point deficit scale at four time points between 4 hours and 168 hours[1].
These are coarse scores. They show that GHK-treated rats circled less or scored better, but they do not describe walking, grip, memory or anything resembling a human recovery scale. Survival is mentioned only in the 2018 methods, which list model mortality of 16.67% in the control group and lower figures in the GHK groups, though the dose labels in that sentence are inconsistent[1].
The Swelling and Enzyme Findings
Brain swelling, or edema, is a major cause of secondary injury after a bleed. In the 2020 study GHK reduced the water content of the brain at 72 hours[2]. It also shifted a balance between matrix metalloproteinases, enzymes that break down tissue scaffolding, and their inhibitor. MMP2 and MMP9 were reduced and TIMP1 was increased[2].
The proposed link was through astrocytes, support cells in the brain that help regulate fluid. GHK reduced the water channel aquaporin 4, which is abundant on astrocytes, in both the rat tissue and in cultured astrocytes[2].
The Cell Experiments
Both papers added cell work to explain the animal results. The 2018 paper used SH-SY5Y cells, a human neuron-like line, exposed to 100 µM hemin, a breakdown product of blood, to imitate the toxic environment of a hemorrhage. GHK improved cell survival and reduced the release of a cell-damage marker, lactate dehydrogenase, in a concentration-dependent way[1]. Related experiments in the paper used GHK at 1 and 10 µM[1].
The proposed route was that GHK lowered activation of the p38 stress pathway, which lowered a small regulatory RNA called miR-339-5p, which allowed the growth factor VEGFA to rise. When the authors forced miR-339-5p up, the protection was partly reversed[1]. In the 2020 paper, cultured astrocytes exposed to hemin survived better with GHK, the PI3K/Akt pathway rose, miR-146a-3p rose and aquaporin 4 fell. Blocking PI3K or Akt reversed the miR-146a-3p increase[2].
These are mechanism stories built from cell lines, each with three repeats per experiment. They are plausible, they are also how many early papers on many compounds read, and neither paper tested whether the same chain operates in the rat brain.
What Neither Study Included
Both studies used one species, one sex and one injury model. The authors of the 2020 paper state that collagenase cannot completely simulate the pathophysiology of human hemorrhage and that they studied astrocytes only, not their interaction with neurons[2]. The 2018 authors likewise say they examined neurons only[1].
Neither methods section describes measuring GHK in blood or brain tissue, so how much of an injected dose reached the injured area is unknown. Neither tested GHK-Cu, an older animal, a female animal, or a longer follow-up than seven days. Both injected the peptide into the abdominal cavity, so neither tested a topical, oral or nasal route.
The 2018 discussion argues that earlier work supports giving GHK orally for hemorrhage[1]. That is the authors’ speculation. Nothing in either paper tested an oral dose.
Funding, Authorship and Independence
Both papers share a first author and an ethics committee, and the 2018 paper describes its own findings as the first to show pretreatment effects of GHK in rats with this kind of hemorrhage[1]. The 2020 paper reports funding from the National Natural Science Foundation of China and other Chinese research grants, and states no commercial or financial conflicts[2]. The 2018 paper also declares no commercial or financial relationships[1].
That is a reassuring disclosure picture, but it is a single laboratory’s work. We found no study of GHK in brain hemorrhage from a different group. For comparison, the site’s page on brain and cognitive decline research covers the wider, thinner neurological literature, and the anxiety study is another example of a single behavioral test in rodents.
Reading It Fairly
Taken together, the studies show that injected GHK, given before or after a collagenase-induced bleed, was associated in male rats with less brain swelling, lower inflammatory signals and better scores on a coarse deficit scale[1][2]. The post-injury design in the second study makes it the more relevant of the two.
They do not show that GHK helps people with brain bleeds, that GHK-Cu does the same, or that any dose is safe or useful outside an experiment. Hemorrhagic stroke is an emergency managed by clinicians. Nothing in these rat studies is a basis for self-treatment with a peptide.
Frequently Asked Questions
Did GHK-Cu help rats with a brain hemorrhage?
The two studies used GHK without copper, not GHK-Cu. In male rats with a collagenase-induced brain bleed, injected GHK was associated with less brain swelling, better neurological deficit scores and more surviving neurons.
Was GHK given before or after the hemorrhage?
Both. The 2018 study gave it for three days before the injury. The 2020 study gave it for three days after the collagenase, though its abstract does not say so and the paper does not state how soon after the first dose was given.
What doses were used?
The 2018 study used 1 and 10 mg/kg. The 2020 study used 1, 5 and 10 micrograms per gram, the same as mg/kg, and credits 5 and 10 with the benefits. All were injected into the abdominal cavity of rats every 24 hours for three days. These are experimental doses, not guidance for any person.
How many animals were in each experiment?
In the 2018 study each assay used 8 rats per group. In the 2020 study each assay used 6 rats per group, and the cell experiments were repeated three times.
Has anyone else repeated these results?
We found no other study of GHK in brain hemorrhage. Both papers come from the same research group, so they have not been independently replicated.
Does this mean a GHK-Cu product protects the brain?
No. The peptide was copper-free and injected into the abdominal cavity of rats. Nothing in these studies tested a topical, oral or nasal product, or a human.
References
- Zhang H, et al. Glycine-Histidine-Lysine (GHK) Alleviates Neuronal Apoptosis Due to Intracerebral Hemorrhage via the miR-339-5p/VEGFA Pathway. Frontiers in Neuroscience (2018). PMID 30294253
- Zhang H, et al. Glycine-Histidine-Lysine (GHK) Alleviates Astrocytes Injury of Intracerebral Hemorrhage via the Akt/miR-146a-3p/AQP4 Pathway. Frontiers in Neuroscience (2020). PMID 33192260
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