Stresscopin (Urocortin III): stress-response peptide studied for heart failure
A natural brain-and-heart signaling peptide that widens blood vessels and protects the heart; being tested in clinical trials for heart failure; not yet an approved drug.
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Named peptide fragment — synthesized for research; ClinicalTrials.gov trials registered for parent compound or class
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Endogenous peptide fragment — receptor binding/activity established in published literature; CT.gov evidence
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What this is
Stresscopin is a 38–40 amino acid neuropeptide belonging to the corticotropin-releasing hormone (CRH) / urocortin family, encoded by the UCN3 gene. It was independently identified in 2001 under two names: "stresscopin" and "stresscopin-related peptide" by Hsu and Hsueh at Stanford (Nature Medicine), and as "urocortin III" (UCN3) by Lewis and colleagues at the Salk Institute (PNAS). The "stresscopin" nomenclature reflects its structural family membership and primary characterization context in hypothalamic stress circuitry; "urocortin III" reflects systematic naming of the third urocortin family member in mammals. Both names refer to the same peptide from the same UCN3 gene.
Stresscopin is the most CRF2-receptor-selective member of the CRH family. CRH itself preferentially binds CRF1; urocortin 1 binds both CRF1 and CRF2; stresscopin (UCN3) is highly selective for CRF2 receptors with negligible CRF1 affinity. This receptor selectivity profile makes stresscopin a useful pharmacological tool for dissecting CRF1 vs. CRF2 biology and a candidate for CRF2-mediated therapeutic applications including heart failure, where vasodilatory and cardioprotective CRF2 signaling is of clinical interest. Stresscopin has been tested in human clinical trials for cardiovascular effects. The stored sequence (TKFTLSLDVPTNIMNLLFNIAKAKNLRAQAAANAHLMAQI, 40 aa) includes a 2-residue N-terminal extension relative to the 38-aa canonical form described in the primary 2001 discovery papers; this may reflect a processing variant or a different cleavage-site annotation, but the CRH-family consensus and CRF2 receptor-binding domain are fully contained in both forms.
History
The CRH family was established when CRH (corticotropin-releasing hormone) was characterized by Vale and colleagues in 1981. Urocortin 1 was added to the family in 1995 (Vaughan et al., Nature). In 2001, two independent groups simultaneously extended the family with a third member.
Hsu and Hsueh at Stanford (Hsu and Hsueh 2001) used computational analysis of genomic databases to identify two novel CRH-related sequences. They named the 38-aa human peptide "stresscopin" and a related shorter peptide "stresscopin-related peptide" (later called UCN2). Importantly, they demonstrated pharmacologically that stresscopin was a selective CRF2 receptor ligand in heterologous expression systems, distinguishing it from CRH and urocortin 1 which had mixed CRF1/CRF2 profiles.
In the same month, Lewis and colleagues at the Salk Institute published a complementary PNAS paper describing the same peptide as "urocortin III" (UCN3), identified through genomic database searching (Lewis and colleagues 2001). Their paper confirmed the CRF2-selective binding profile and characterized UCN3 mRNA expression in hypothalamic, brain stem, and peripheral tissue regions relevant to stress and energy homeostasis.
The subsequent cardiovascular biology of stresscopin/UCN3 was established by Chanalaris and colleagues (2003), who demonstrated that stresscopin protected cardiomyocytes against ischemia-reperfusion injury in a CRF2-receptor-dependent manner, providing the mechanistic basis for subsequent heart failure clinical trials. Edinburgh clinical groups then conducted the first human trials of urocortin peptides including UCN3/stresscopin in forearm blood flow models and heart failure patients in the 2010s.
What it does
Selective CRF2 receptor agonism: Stresscopin binds CRF2 receptors with high affinity and activates Gs-coupled adenylyl cyclase, raising intracellular cAMP. Its selectivity for CRF2 over CRF1 is orders of magnitude greater than CRH or urocortin 1, making stresscopin the prototypic selective CRF2 agonist. CRF2 receptors are expressed in cardiac muscle, vascular smooth muscle, skeletal muscle, brain, and pituitary. This receptor expression profile informs stresscopin's range of physiological effects.
Vasodilation and positive inotropic cardiac effects: CRF2 activation in the cardiovascular system produces vasodilation and increases myocardial contractility. In human forearm brachial artery infusion studies, intra-arterial urocortin 3 (stresscopin) produced vasodilation in healthy volunteers, comparable to but mechanistically distinct from prostacyclin-mediated vasodilation. The positive inotropic and vasodilatory profile is the rationale for testing stresscopin in heart failure.
Cardioprotection against ischemia-reperfusion injury: In isolated cardiomyocyte models, stresscopin reduces cell death following simulated ischemia-reperfusion injury in a CRF2-receptor-dependent, PKA/cAMP-dependent manner (Chanalaris and colleagues 2003). This cardioprotective effect parallels the well-established ischemic preconditioning mechanism, placing CRF2 signaling alongside adenosine, bradykinin, and opioid receptor pathways that confer cardioprotection. The magnitude and clinical relevance of this in vitro cardioprotection have not been confirmed in human myocardium.
Regulation of food intake and stress response: Stresscopin expression in the hypothalamus and brain stem supports roles in energy homeostasis and stress-adaptive behaviors. CRF2-selective agonism in hypothalamic circuits modulates food intake — a role consistent with CRF2's expression in the arcuate nucleus and regions connected to feeding control. Stresscopin differs from CRH in not producing the classic anxiogenic effects of CRF1 activation, though it can still modulate stress-related behavior through CRF2 circuits.
Distinction from urocortin 1 and CRH: The three CRH family members show an ordered selectivity shift from CRF1-preferential (CRH), to dual-receptor (urocortin 1), to CRF2-selective (stresscopin). This gradient means that physiological effects attributed to "CRF2" in blocking experiments may reflect stresscopin's specific contribution, while effects blocked by both CRF1 and CRF2 antagonists typically involve CRH or urocortin 1. Stresscopin's use as a selective CRF2 agonist in pharmacological studies is well established and arguably more informative than non-selective approaches.
Evidence
- Discovery and CRF2-selective receptor binding profile. Hsu and Hsueh (2001) used computational database analysis to identify two novel CRH-family peptides from human genomic sequences, named stresscopin (38 aa) and stresscopin-related peptide. Radioligand competition assays in HEK293 cells expressing cloned CRF1 or CRF2 receptors demonstrated that stresscopin displaced a CRF2-selective radioligand at low nanomolar concentrations while showing negligible affinity for CRF1 — the first demonstration of a naturally occurring CRF2-selective agonist in humans.
- Independent identification as urocortin III; genomic and expression analysis. Lewis and colleagues (2001) simultaneously and independently identified the same gene product as "urocortin III" (UCN3) through database screening and confirmed CRF2-selective binding. Their paper also characterized UCN3 mRNA expression by in situ hybridization in mouse brain, identifying expression in hypothalamic regions (ventromedial hypothalamic nucleus, Barrington's nucleus) distinct from CRH and urocortin 1 expression patterns — providing anatomical support for distinct physiological roles for each CRF family member.
- Cardioprotective effects in ischemia-reperfusion model. Chanalaris and colleagues (2003) tested stresscopin and stresscopin-related peptide (UCN2) on isolated ventricular cardiomyocytes subjected to simulated ischemia-reperfusion injury. Both peptides significantly reduced cell death compared to controls, and the protective effect was reversed by a selective CRF2 receptor antagonist, confirming receptor-mediated rather than non-specific protection. The mechanism involved cAMP elevation and PKA activation downstream of CRF2 signaling. This paper established the cardiac pharmacology of stresscopin and provided rationale for subsequent human trials in heart failure.
Myths and misconceptions
- "Stresscopin causes stress-like anxiety because it belongs to the CRH family." CRH's anxiogenic effects are mediated through CRF1 receptors. Stresscopin is CRF2-selective and does not appreciably activate CRF1. Rodent studies with selective CRF2 agonists consistently produce anxiolytic or anxiety-neutral effects rather than the anxiogenic behavioral profile of CRF1 activation. The name "stresscopin" reflects its gene family membership and hypothalamic expression context, not a pro-anxiety function.
- "Stresscopin and urocortin are the same peptide." The urocortin family has three members in mammals: urocortin 1 (UCN1), urocortin 2 (UCN2, also called stresscopin-related peptide), and urocortin 3 (UCN3, stresscopin). Urocortin 1 has dual CRF1/CRF2 affinity; UCN2 and UCN3/stresscopin are CRF2-selective. They have related but distinct sequences, different gene loci, non-overlapping brain expression patterns, and differ quantitatively in their cardiovascular effects. Clinical trials in Edinburgh tested multiple urocortins in separate protocol arms to characterize their distinct cardiovascular profiles.
- "Because stresscopin is in clinical trials, it is a developed drug." The Edinburgh forearm blood flow trials and heart failure study are exploratory pharmacology studies establishing proof-of-concept in human subjects — not Phase 2/3 trials for regulatory approval. The trials used research-grade synthetic stresscopin administered by intravenous infusion under controlled conditions. No stresscopin formulation has been developed as a pharmaceutical product or submitted for regulatory review as of 2026.
Common questions
Q: How does stresscopin compare to urocortin 1 (Urocortin), and what does CRF2 selectivity mean therapeutically? A: Urocortin 1 binds both CRF1 and CRF2 with comparable affinity, while stresscopin is selective for CRF2 by at least 100-fold relative to CRF1. This selectivity matters therapeutically: CRF1 antagonism has been explored for anxiety and depression (with disappointing clinical trial results), while CRF2 agonism for heart failure represents a distinct and non-overlapping pharmacological approach. Stresscopin's pure CRF2 profile means its cardiovascular vasodilatory and cardioprotective effects are attributable specifically to CRF2, without CRF1-mediated HPA axis activation or anxiogenic side effects that would limit clinical use.
Q: Why is a stress-related peptide relevant to heart failure treatment? A: The connection is not intuitive but mechanistically consistent. CRF2 receptors are expressed in cardiomyocytes and vascular smooth muscle, where they mediate vasodilation and positive inotropy through cAMP/PKA signaling — a profile that mirrors the ideal pharmacological target in heart failure (reduce afterload, increase contractility). The "stress" connection is through the peptide's family membership and hypothalamic expression, not through its cardiac effects. The cardiac CRF2 receptor system is essentially independent of the classic hypothalamic-pituitary-adrenal (HPA) stress axis that CRH activates through CRF1. Stresscopin's cardiac biology can therefore be pursued therapeutically without the glucocorticoid-related side effects of CRF1 activation.
Related peptides
- Urocortin — Urocortin (urocortin 1): the founding CRH-family urocortin with dual CRF1/CRF2 affinity; stresscopin's CRF2 selectivity should be understood in contrast to urocortin 1's non-selective profile; both are vasodilatory but through partially overlapping receptor pharmacology
- Cortistatin-14 — Cortistatin-14: another research-stage neuropeptide with partial receptor overlap with an established family (somatostatin), analogous to stresscopin's relationship to CRH; both illustrate how later-discovered family members with more selective receptor profiles can reveal biology masked by non-selective earlier ligands
- Corticotropin — ACTH / Corticotropin: the adrenal output of the HPA axis that CRH initiates; stresscopin's CRF2-selective profile avoids activating the CRH→ACTH→cortisol cascade that limits CRF1-activating approaches to CNS disorders
Research directions for this peptide, selected from the current sources — hypotheses you can explore and model. None of it is proven yet; tap any one to see the full thinking.
Could stresscopin made locally in the gut act as a local stress signal that controls bowel motility during stressful events?
If stresscopin has a gut-specific role, it could lead to new treatments for conditions like irritable bowel syndrome where stress triggers painful cramps or diarrhea, helping millions of people who currently have no good options.
Does stresscopin help a failing heart by acting on the heart cells themselves, separate from its blood-vessel-relaxing effects?
If stresscopin protects heart muscle directly, it could be particularly valuable for patients whose heart failure stems from muscle damage rather than high blood pressure, potentially expanding who can benefit from this treatment.
Could stresscopin, by switching on the CRF2 receptor, quiet overactive immune cells in the brain that may contribute to depression or PTSD?
If this proves out, it could point to a new treatment direction for stress-related mental health conditions, since current antidepressants do not target brain inflammation. This is an early-stage idea that has not yet been tested for stresscopin.
▸full evidence table2 metrics
| metric | value | tool |
|---|---|---|
| ipTM | 0.7950857281684875 | boltz-2 |
| ranking score | 0.6741395592689514 | boltz-2 |
▸3-letter notation
▸recipeboltz-2 2.2.1
| parameter | value |
|---|---|
| model | boltz-2 2.2.1 |
| weights | — |
| hardware | vast_v100_32gb |
| mlx version | — |
| python | — |
| random seed | 1 |
| msa strategy | colabfold_local |
| runtime | — |
| predicted by | — |
| predicted at | 2026-05-22 |
▸citationbibtex
@peptide{pep10673,
sequence = {TKFTLSLDVPTNIMNLLFNIAKAKNLRAQAAANAHLMAQI},
target = {crhr2},
author = {peptidemodel},
year = {2026},
status = {bioassayed}
}