Xenin
Also known as: Xenin-25, Xenin-8, xenin-25 amide, Xen, Xenin 18-25, xenin-8-Gln
Gastrointestinal peptide hormone; neurotensin-related peptide; 25-amino acid incretin-associated peptide secreted from intestinal K-cells
What it is
Researchers studying type 2 diabetes and postprandial insulin secretion have investigated xenin-25 as a potential therapeutic peptide. It is co-secreted from gut K-cells alongside GIP after meals, and interest centers on its ability to amplify insulin release, slow gastric emptying, and suppress appetite — effects that appear to diminish as diabetes progresses.
The scientific side
xenin-25 is a 25-amino acid peptide hormone secreted from the same enteroendocrine K-cells as the incretin hormone glucose-dependent insulinotropic polypeptide (GIP). Its biological actions are mediated at least in part through the neurotensin receptor subtype 1 (NTSR1), although some actions are independent of this receptor. The primary described mechanism in human studies involves xenin-25 amplifying GIP-mediated insulin secretion during and after nutrient ingestion; however, this amplification is blunted in people with type 2 diabetes, suggesting that failure of xenin signaling may be an early step in diabetes pathogenesis. In animal and in vitro models, xenin-25 promotes pancreatic beta-cell survival and proliferation, induces dose-dependent insulin release, and augments glucose-stimulated insulin secretion via neurotensin receptor subtypes in pancreatic islets without requiring NTR-2 activation. In the gastrointestinal tract, xenin-25 modulates intestinal anion secretion via a C-terminal pentapeptide domain containing an Arg residue at position 21, inhibits then stimulates colonic circular muscle contractions through NTSR1 and nitric oxide–dependent pathways, and stimulates pancreatic exocrine secretion through peripheral cholinergic nerves. Xenin-25 also delays gastric emptying and attenuates postprandial glucose excursions in humans. In the central nervous system, intracerebroventricular administration of xenin activates nesfatin-1 neurons in multiple hypothalamic and brainstem nuclei, and this pathway contributes to xenin-induced suppression of food intake in rodents. Native xenin-25 is subject to rapid proteolytic degradation in plasma, which limits its biological half-life to minutes; this has motivated the development of enzymatically stable analogues through C-terminal truncation, amino acid substitution, and lipidation strategies that extend plasma half-life and improve metabolic efficacy in preclinical models. Elevated circulating xenin-25 levels have been observed in gestational diabetes mellitus and in intrahepatic cholestasis of pregnancy, positioning xenin as a candidate biomarker in these conditions.
Class: Gastrointestinal peptide hormone; neurotensin-related peptide; 25-amino acid incretin-associated peptide secreted from intestinal K-cells
Administration & storage
- Administration
- Intravenous continuous infusion (human Phase 1 trialsprimed then constant rate)Subcutaneous injection (rat gastroprotection studiesPMID 42260116)Intraperitoneal injection (mouse metabolic and satiety studies)Intracerebroventricular injection (rat central nervous system studiesPMID 37844783)
- Storage
- No specific stability data for reconstituted xenin-25 were reported in the fetched abstracts. The peptide undergoes rapid proteolytic degradation in native plasma (half-life described as minutes), which is why stable analogues and albumin-buffered IV formulations were used in research. Long-term storage conditions for research-grade peptide are not described in the abstracts reviewed.
Legal & regulatory status
Not approved as a drug. Used exclusively as an investigational agent in NIH-funded Phase 1 clinical studies (NCT00798915, NCT00949663, NCT01951729, NCT02204813) at Washington University School of Medicine. No IND…
No mention of xenin or xenin-25 appearing on the WADA prohibited list was found in any fetched abstract or trial record.
No approval or regulatory designation found in the fetched abstracts or clinical trial records.
What it's studied for
- Amplification of GIP-mediated insulin secretion in type 2 diabetes and pre-diabetes Phase 1 human trials (completed, basic science)
- Delaying gastric emptying and reducing postprandial glucose Phase 1 human study (pilot, single-centre)
- Appetite suppression and satiety signaling Preclinical (rodent) and mechanistic human data
- Diabetes-obesity treatment via stable xenin analogues and hybrid peptides Preclinical (mouse models of high-fat feeding and ob/ob)
- Neuroprotection and Alzheimer's disease-related pathology Preclinical (APP/PS1 mouse model)
- Gastroprotection in acute gastric injury Preclinical (rat NSAID-induced ulcer model)
- Biomarker role in gestational diabetes mellitus and intrahepatic cholestasis of pregnancy Observational human studies (cross-sectional, small sample sizes)
Safety signals
- Diarrhea
- Blunted effect in type 2 diabetes — risk of underestimating insulinotropic response
- Positive correlation with perceived stress, anxiety, depressiveness, and eating disorder symptoms in obese women
- Elevated levels in gestational diabetes mellitus and intrahepatic cholestasis of pregnancy — uncertain causality
- Pancreatitis risk flagged as exclusion criterion in all clinical trials
- Potential for xenin antibody development with repeated IV administration
- Rapid native peptide degradation limits exposure and may cause unpredictable pharmacokinetics if analogues are used
All studies (2)
Frequently asked
Is xenin-25 approved for use in humans?
No. Based on the published research abstracts reviewed, xenin-25 has only been administered to humans in completed Phase 1 investigational studies conducted at Washington University School of Medicine, funded by the NIH. It has no FDA approval, Health Canada approval, or any other regulatory authorisation as a medical treatment. All human dosing was by intravenous infusion under strict clinical trial conditions.
Can xenin-25 help with type 2 diabetes?
Preclinical studies and Phase 1 human trials have shown that xenin-25 can amplify the insulin-releasing effects of GIP in people without diabetes or with pre-diabetes. However, this effect appears to be absent or significantly reduced in people who already have type 2 diabetes. No clinical trials have tested whether xenin-based therapies improve long-term outcomes in T2DM patients, and no approved xenin-based diabetes treatment currently exists.
What are the differences between xenin-25, xenin-8, and the various analogues?
Xenin-25 is the full 25-amino acid native peptide secreted from gut K-cells. Xenin-8 (and related forms like xenin-8-Gln) is a C-terminal octapeptide fragment that retains insulin-releasing and GIP-potentiating activity in preclinical studies. Stable analogues such as xenin-25(gln), Psi-xenin-6, and lipidated forms like Xenin-25[Lys(13)PAL] have been engineered to resist plasma degradation and extend biological half-life — all are research compounds not approved for human use.
Does xenin-25 suppress appetite?
In rodent studies, both central (intracerebroventricular) and peripheral xenin administration reduced food intake. Central administration activated nesfatin-1 neurons in brain regions associated with satiety. C-terminal fragment analogues also showed appetite-suppressive effects in fasted mice. No controlled human data on food intake suppression were found in the abstracts reviewed.
Is xenin on the WADA banned list?
No mention of xenin appearing on the World Anti-Doping Agency prohibited list was found in any of the research abstracts or clinical trial records reviewed. However, this information may change; athletes should consult current WADA documentation directly.