Omneity® Pellets
All-In-One Vitamin & Mineral Pellet
Evidence for dopamine production and distribution of dopamine D2 receptors in the equine gastrointestinal mucosa and pancreas.
Abstract: Insulin dysregulation in horses is characterised by hyperinsulinaemia and/or tissue insulin resistance and is associated with increased risk of laminitis. There is growing evidence in other species that dopamine attenuates insulin release from the pancreas; however, this has yet to be examined in horses. The present study aimed to identify whether there are cells capable of producing or responding to dopamine within the equine gastrointestinal mucosa and pancreas. Tissue samples were collected from the stomach, small and large intestines, and pancreas of six mature horses following euthanasia. Samples of stomach contents and faeces were also collected. Immunohistochemistry was performed to identify tyrosine hydroxylase (TH), the rate-limiting enzyme for dopamine production, and dopamine D2 receptors in tissue sections. Additional immunostaining for glucagon, insulin and chromogranin A was performed to identify α cells, β cells and enteroendocrine cells, respectively. Gastric parietal cells expressed both TH and D2 receptors, indicating that they are capable of both producing and responding to dopamine. Dopamine was quantified in stomach contents and faeces by high-performance liquid chromatography with electrochemical detection, with similar concentrations found at both sites. Dopamine D2 receptors were expressed in duodenal epithelial cells but not more distally. A subset of enteroendocrine cells, located sporadically along the gastrointestinal tract, were found to be immunopositive for the D2 receptor. In pancreatic islets, TH was present in α cells, while D2 receptors were strongly expressed in β cells and variably expressed in α cells. These findings are consistent with studies of other species; however, dynamic studies are required to further elucidate the role of dopamine in the modulation of insulin and glucagon secretion in horses. This descriptive study provides preliminary evidence for a potential role of dopamine to act as a paracrine messenger in the gastrointestinal mucosa and endocrine pancreas of horses.
Copyright: © 2024 Galinelli et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Publication Date: 2024-02-27 PubMed ID: 38412155DOI: 10.1371/journal.pone.0298660Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
The study investigates and provides evidence for the presence of cells that respond to or produce dopamine within the gastrointestinal mucosa and pancreas of horses. This research aims to shed light on the potential influence of dopamine in modulating insulin release, given its association in other species.
Research Methodology
- The researchers collected tissue samples from the stomach, small and large intestines, and pancreas of six mature horses after euthanasia.
- Immunohistochemistry was used to identify tyrosine hydroxylase (TH), the rate-limiting enzyme for dopamine production, and dopamine D2 receptors in the tissue sections.
- The researchers also performed additional immunostaining to identify alpha cells, beta cells, and enteroendocrine cells.
- The concentration of dopamine in stomach contents and faeces was identified using high-performance liquid chromatography with electrochemical detection.
Research Findings
- The study found that gastric parietal cells expressed both TH and D2 receptors, suggesting they have the capability to produce and respond to dopamine.
- Similar concentrations of dopamine were found in the stomach contents and faeces.
- Dopamine D2 receptors were present in duodenal epithelial cells, and a subset of enteroendocrine cells across the gastrointestinal tract were found to be positive for the D2 receptor.
- In pancreatic islets, TH was present in alpha cells, whereas D2 receptors were strongly expressed in beta cells and variably expressed in alpha cells.
Research Implications
- The study’s findings are in line with previous studies from other species and suggest a potential role of dopamine as a paracrine messenger in the gastrointestinal mucosa and endocrine pancreas of horses.
- The evidence of dopamine influence on insulin release from the pancreas in horses may provide important insights into the treatment of insulin dysregulation in these animals.
- Though the research provides preliminary evidence, further dynamic studies are required to better understand the role of dopamine in the secretion of insulin and glucagon in horses.
Cite This Article
APA
Galinelli NC, Bamford NJ, de Laat MA, Sillence MN, Harris PA, Bailey SR.
(2024).
Evidence for dopamine production and distribution of dopamine D2 receptors in the equine gastrointestinal mucosa and pancreas.
PLoS One, 19(2), e0298660.
https://doi.org/10.1371/journal.pone.0298660 Publication
Researcher Affiliations
- Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Parkville, Victoria, Australia.
- Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Parkville, Victoria, Australia.
- School of Biology and Environmental Science, Faculty of Science, Queensland University of Technology, Brisbane, Queensland, Australia.
- School of Biology and Environmental Science, Faculty of Science, Queensland University of Technology, Brisbane, Queensland, Australia.
- Equine Studies Group, Waltham Petcare Science Institute, Melton Mowbray, United Kingdom.
- Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Parkville, Victoria, Australia.
Conflict of Interest Statement
The authors have declared that no competing interests exist.
Citations
This article has been cited 4 times.- Pasricha TS, Kulkarni S. Dopaminergic signalling in gastrointestinal health and disease. Nat Rev Gastroenterol Hepatol 2025 Oct;22(10):696-707.
- Hong J, Kang J, Zuo J, Fang Y, Liu C, Li J, Chen Z. Development of (18)F-Labeled Deuterated Tropane Derivatives with High Metabolic Stability for PET Imaging of the Dopamine Transporter. Mol Imaging Biol 2025 Jun;27(3):431-441.
- Su T, Zhou L, Peng B, Du W, Liu X, Li Z, Zhao Y, Han X, Liu C, Wang Z. The dopamine receptor agonist rotigotine attenuated indomethacin-induced enteropathy in the small intestinal mucosa of mice. Mol Biol Rep 2025 Mar 24;52(1):335.
- Galinelli NC, Bamford NJ, Erdody ML, Mackenzie SA, Warnken T, Harris PA, Sillence MN, Bailey SR. Effect of pergolide treatment on insulin dysregulation in horses and ponies with pituitary pars intermedia dysfunction. Equine Vet J 2025 Nov;57(6):1612-1622.
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
