Dogs and Rats Use Different Brain Peptides to Control Appetite
Pancreatic polypeptides and dynorphin A stimulated feeding in satiated dogs, while NPY and galanin (which work in rats) did not — showing species differ significantly in appetite regulation.
Quick Facts
What This Study Found
Pancreatic polypeptides and dynorphin A stimulated feeding in satiated dogs. NPY, galanin, norepinephrine, and GRH did not, despite working in rats.
Key Numbers
How They Did This
Satiated dogs received third ventricle injections of various neuropeptides through chronic cannulas. Food and water intake were measured over specified periods.
Why This Research Matters
Most feeding research is done in rats. This study shows that dogs use different brain peptide systems to control appetite. Since dogs are closer to humans in many ways, this matters for translating appetite research to people.
The Bigger Picture
This species difference challenges the assumption that rat appetite data translates to larger animals and humans. It suggests that weight loss drugs developed in rats may not work as expected in people.
What This Study Doesn't Tell Us
Animal study in dogs. Brain injections do not reflect normal physiology. Small number of peptides tested. The dog may still differ from humans in appetite regulation.
Questions This Raises
- ?Which appetite regulation system does the human brain use — the rat model or the dog model?
- ?Should appetite drug development prioritize dog or primate models over rodents?
Trust & Context
- Key Stat:
- NPY ineffective in dogs NPY, the most potent appetite stimulator in rats, had no feeding effect in dogs — highlighting critical species differences
- Evidence Grade:
- Preliminary animal study comparing species responses. Important for translational medicine but limited number of peptides tested.
- Study Age:
- Published in 1991. Species differences in appetite regulation remain a significant challenge in obesity drug development.
- Original Title:
- Neuropeptide regulation of feeding in dogs.
- Published In:
- The American journal of physiology, 261(3 Pt 2), R588-94 (1991)
- Authors:
- Inui, A(2), Okita, M, Nakajima, M, Inoue, T, Sakatani, N, Oya, M, Morioka, H, Okimura, Y, Chihara, K, Baba, S
- Database ID:
- RPEP-00196
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
Why are species differences in appetite important?
Billions of dollars are spent developing obesity drugs based on rat brain appetite research. If dogs (and potentially humans) use different peptide systems, many of these drugs may fail in clinical trials — as indeed many have.
Does this mean dynorphin controls human appetite?
It's possible. Dynorphin stimulated feeding in both rats and dogs, making it one of the more conserved appetite signals across species. This supports the known link between the opioid system and food craving in humans.
Read More on RethinkPeptides
Cite This Study
https://rethinkpeptides.com/research/RPEP-00196APA
Inui, A; Okita, M; Nakajima, M; Inoue, T; Sakatani, N; Oya, M; Morioka, H; Okimura, Y; Chihara, K; Baba, S. (1991). Neuropeptide regulation of feeding in dogs.. The American journal of physiology, 261(3 Pt 2), R588-94.
MLA
Inui, A, et al. "Neuropeptide regulation of feeding in dogs.." The American journal of physiology, 1991.
RethinkPeptides
RethinkPeptides Research Database. "Neuropeptide regulation of feeding in dogs." RPEP-00196. Retrieved from https://rethinkpeptides.com/research/inui-1991-neuropeptide-regulation-of-feeding
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.