In Fish, GIP Controls Appetite Rather Than Lowering Blood Sugar — Opposite of Mammals
Unlike its blood sugar-lowering role in mammals, GIP acts primarily as an appetite regulator in grass carp, actually raising blood glucose while modulating feeding behavior.
Quick Facts
What This Study Found
GIP functions as an appetite regulator rather than a hypoglycemic incretin in grass carp, raising blood glucose and modulating feeding behavior — opposite to its mammalian role.
Key Numbers
How They Did This
Intraperitoneal injection of synthetic grass carp GIP; 24-hour monitoring of blood glucose, hepatic gene expression (g6pase, pepck), and feeding behavior.
Why This Research Matters
Understanding how incretin hormones evolved different functions across species provides insights into metabolic regulation and could improve aquaculture feeding strategies.
The Bigger Picture
This challenges the assumption that incretin biology is universal — GIP's role in fish versus mammals shows how evolution repurposes the same peptide hormone for different metabolic needs across species.
What This Study Doesn't Tell Us
Single fish species studied; acute injection may not reflect chronic physiological role; grass carp are herbivorous, which may influence incretin function.
Questions This Raises
- ?When in evolution did GIP switch from appetite regulation to blood sugar lowering?
- ?Could GIP-based strategies optimize feed timing in aquaculture?
Trust & Context
- Key Stat:
- Opposite function in fish vs mammals GIP raises blood glucose and regulates appetite in grass carp instead of lowering blood sugar
- Evidence Grade:
- Controlled fish study with gene expression analysis — strong evidence in aquaculture model.
- Study Age:
- Published in 2026, contributing to comparative incretin biology.
- Original Title:
- Glucose-dependent insulinotropic polypeptide (GIP) acts as an appetite regulator rather than as a hypoglycemic incretin in grass carp.
- Published In:
- Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology, 283, 111192 (2026)
- Authors:
- Cheng, Danhong, Sun, Manjie, Huang, Jinqian, Luo, Shan, Chen, Haotian, Jin, Shengzhen, Zhang, Yanpeng, Yuan, Xiaochen
- Database ID:
- RPEP-15016
Evidence Hierarchy
Frequently Asked Questions
What is GIP?
GIP (glucose-dependent insulinotropic polypeptide) is a gut hormone. In humans, it helps lower blood sugar after meals. In fish, this study found it does the opposite — raising blood sugar while controlling appetite.
Why does GIP work differently in fish?
Fish and mammals evolved under very different metabolic pressures. Fish may need GIP to maintain blood sugar during fasting and regulate feeding patterns, while mammals evolved to use it for insulin release after meals.
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Cite This Study
https://rethinkpeptides.com/research/RPEP-15016APA
Cheng, Danhong; Sun, Manjie; Huang, Jinqian; Luo, Shan; Chen, Haotian; Jin, Shengzhen; Zhang, Yanpeng; Yuan, Xiaochen. (2026). Glucose-dependent insulinotropic polypeptide (GIP) acts as an appetite regulator rather than as a hypoglycemic incretin in grass carp.. Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology, 283, 111192. https://doi.org/10.1016/j.cbpb.2025.111192
MLA
Cheng, Danhong, et al. "Glucose-dependent insulinotropic polypeptide (GIP) acts as an appetite regulator rather than as a hypoglycemic incretin in grass carp.." Comparative biochemistry and physiology. Part B, 2026. https://doi.org/10.1016/j.cbpb.2025.111192
RethinkPeptides
RethinkPeptides Research Database. "Glucose-dependent insulinotropic polypeptide (GIP) acts as a..." RPEP-15016. Retrieved from https://rethinkpeptides.com/research/cheng-2026-glucosedependent-insulinotropic-polypeptide-gip
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkPeptides research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.