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Evidence for the effect of serotonin receptor 1A gene (HTR1A) polymorphism on tractability in Thoroughbred horses.
Abstract: Tractability, or how easily animals can be trained and controlled, is an important behavioural trait for the management and training of domestic animals, but its genetic basis remains unclear. Polymorphisms in the serotonin receptor 1A gene (HTR1A) have been associated with individual variability in anxiety-related traits in several species. In this study, we examined the association between HTR1A polymorphisms and tractability in Thoroughbred horses. We assessed the tractability of 167 one-year-old horses reared at a training centre for racehorses using a questionnaire consisting of 17 items. A principal components analysis of answers contracted the data to five principal component (PC) scores. We genotyped two non-synonymous single nucleotide polymorphisms (SNPs) in the horse HTR1A coding region. We found that one of the two SNPs, c.709G>A, which causes an amino acid change at the intracellular region of the receptor, was significantly associated with scores of four of five PCs in fillies (all Ps < 0.05) and one PC in colts (P < 0.01). Horses carrying an A allele at c.709G>A showed lower tractability. This result provides the first evidence that a polymorphism in a serotonin-related gene may affect tractability in horses with the effect partially different depending on sex.
© 2015 Stichting International Foundation for Animal Genetics.
Publication Date: 2015-11-19 PubMed ID: 26763159DOI: 10.1111/age.12384Google 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
- Research Support
- Non-U.S. Gov't
Summary
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The study investigates the link between serotonin receptor 1A gene (HTR1A) polymorphisms and the ease of training and controlling, or tractability, in Thoroughbred horses. Researchers found that the A allele of a specific gene polymorphism (c.709G>A) in the HTR1A led to lower tractability in horses, and this effect varied slightly by sex.
Objective of the Research
- The aim of the research was to understand the genetic basis of tractability, a crucial behavioral trait in domestic animals. It specifically focused on Thoroughbred horses.
- The scientists hypothesized that polymorphisms (variations) in the HTR1A gene, which previously have been connected to anxiety-related traits in other species, could have an association with tractability in these horses.
Methodology
- This study involved an assessment of 167 one-year-old Thoroughbred horses from a training center. Tractability was evaluated through a questionnaire containing 17 items.
- The researchers utilized a statistical method, principal components analysis (PCA), to simplify the responses from the questionnaire into five principal component (PC) scores.
- They genotyped the horses for two non-synonymous single nucleotide polymorphisms (SNPs) in the HTR1A coding region. These type of SNPs result in a different amino acid, and consequently a change in the resultant protein.
Results
- The research found a specific SNP, c.709G>A, in the HTR1A gene to be significantly associated with tractability. This polymorphism leads to an amino acid change in the serotonin receptor.
- Horses carrying the A allele at this SNP showed reduced tractability.
- The SNP’s effect on tractability was found to vary by sex. It influenced four out of five PC scores in fillies, female horses, and a single PC score in colts, young male horses.
Conclusion
- This study is the first to provide evidence of a serotonin-related gene’s polymorphism influencing tractability in horses.
- It’s important to note that the effect of the HTR1A gene polymorphism on tractability is partially sex-dependent.
- These findings can potentially aid future genetics-based tractability development strategies in horse breeding practices.
Cite This Article
APA
Hori Y, Tozaki T, Nambo Y, Sato F, Ishimaru M, Inoue-Murayama M, Fujita K.
(2015).
Evidence for the effect of serotonin receptor 1A gene (HTR1A) polymorphism on tractability in Thoroughbred horses.
Anim Genet, 47(1), 62-67.
https://doi.org/10.1111/age.12384 Publication
Researcher Affiliations
- Department of Psychology, Graduate School of Letters, Kyoto University, Yoshida-honmachi Sakyo, Kyoto, 606-8501, Japan.
- Japan Society for the Promotion of Science, Kojimachi Business Center Building, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo, 102-0083, Japan.
- Genetic Analysis Department, Laboratory of Racing Chemistry, 1731-2 Tsurutamachi, Utsunomiya, Tochigi, 320-0851, Japan.
- Department of Clinical Veterinary Science, Obihiro University of Agriculture and Veterinary Medicine, 2-11 Inada-cho, Obihiro, Hokkaido, 080-8555, Japan.
- Hidaka Training and Research Center, Japan Racing Association, 535-13 Nishicha, Urakawa, Hokkaido, 057-0171, Japan.
- Hidaka Training and Research Center, Japan Racing Association, 535-13 Nishicha, Urakawa, Hokkaido, 057-0171, Japan.
- Wildlife Research Center, Kyoto University, 2-24 Tanaka-Sekiden-cho, Sakyo, Kyoto, 606-8203, Japan.
- Wildlife Genome Collaborative Research Group, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki, 305-8506, Japan.
- Department of Psychology, Graduate School of Letters, Kyoto University, Yoshida-honmachi Sakyo, Kyoto, 606-8501, Japan.
MeSH Terms
- Alleles
- Animals
- Behavior, Animal
- Female
- Genotype
- Horses / genetics
- Male
- Personality / genetics
- Polymorphism, Single Nucleotide
- Receptor, Serotonin, 5-HT1A / genetics
Citations
This article has been cited 8 times.- Todd ET, Fromentier A, Sutcliffe R, Running Horse Collin Y, Perdereau A, Aury JM, Èche C, Bouchez O, Donnadieu C, Wincker P, Kalbfleisch T, Petersen JL, Orlando L. Imputed genomes of historical horses provide insights into modern breeding. iScience 2023 Jul 21;26(7):107104.
- Holtby AR, McGivney BA, Browne JA, Katz LM, Murphy KJ, Hill EW. Variation in salivary cortisol responses in yearling Thoroughbred racehorses during their first year of training. PLoS One 2023;18(4):e0284102.
- Yokomori T, Ohnuma A, Tozaki T, Segawa T, Itou T. Identification of Personality-Related Candidate Genes in Thoroughbred Racehorses Using a Bioinformatics-Based Approach Involving Functionally Annotated Human Genes. Animals (Basel) 2023 Feb 20;13(4).
- Han H, McGivney BA, Farries G, Katz LM, MacHugh DE, Randhawa IAS, Hill EW. Selection in Australian Thoroughbred horses acts on a locus associated with early two-year old speed. PLoS One 2020;15(2):e0227212.
- Ramadan S, Nowier AM, Hori Y, Inoue-Murayama M. The association between glutamine repeats in the androgen receptor gene and personality traits in dromedary camel (Camelus dromedarius). PLoS One 2018;13(2):e0191119.
- Yokomori T, Tozaki T, Segawa T, Itou T. Genomic regions and candidate genes associated with forehead whorl positioning in Thoroughbred horses. J Equine Sci 2025;36(1):11-18.
- Yokomori T, Tozaki T, Ohnuma A, Ishimaru M, Sato F, Hori Y, Segawa T, Itou T. Non-Synonymous Substitutions in Cadherin 13, Solute Carrier Family 6 Member 4, and Monoamine Oxidase A Genes are Associated with Personality Traits in Thoroughbred Horses. Behav Genet 2024 Jul;54(4):333-341.
- Saito I, Nakamura K, Tozaki T, Hano K, Takasu M. Genetic characterization of Japanese native horse breeds by genotyping variants that are associated with phenotypic traits. J Equine Sci 2023 Dec;34(4):115-120.
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