Stress' Impact on Equine Gene Activation

Stress' Impact on Equine Gene Activation

Researchers found that chronic stress in horses could lead to an increased susceptibility to disease due to the activation of certain genes.

Photo: Erica Larson, News Editor

New research by French behavior scientists and geneticists reveals that chronic stress can actually affect horses at a genetic level—specifically, in the process of gene activation.

According to Aline Foury, MSc, researcher at the National Institute for Agricultural Research (INRA) in Bordeaux, long-term stressful situations can cause alterations in the activation of genes that would “express”—or create and release—certain molecules through a genetic process known as transcription. At the 2013 French Equine Research Day, held earlier this year in Paris, Foury said different genes express specific molecules known as “messenger RNA,” and each particular combination creates what is called a “regulatory pathway.”

Stress-induced alterations of the gene activation in these regulatory pathways appear to, in turn, affect biological processes such as inflammatory responses and cell survival. And when these are affected, the horse’s general health is affected, as well.

In a recent study on the topic, Foury and colleagues monitored 19 Welsh pony foals starting when at 10 months of age. The team separated the ponies into two experimental groups: impoverished conditions and enriched conditions. The team housed the impoverished ponies in small, individual stalls and granted them one hour of individual pasture time three days a week. They fed these ponies three times a day and mostly left the animals alone.

The team housed enriched ponies in much larger individual stalls for eight hours a day, five days a week, but allowed the animals access to pasture with pasturemates for the remainder of the time. These ponies consumed a variety of feeds three times daily and received regular attention, care, and stimuli from handlers.

After 12 weeks, the researchers analyzed the blood cells' transcriptome (all the messenger RNA molecules produced from the genes activated in blood cells) from samples they collected from all the ponies.

In the impoverished group, Foury and colleagues identified a marked difference in the activation of three transcription factors compared to the enriched group: CREB/ATF, GATA, and IRF1. CREB/ATF proteins are involved in many processes, including memory and learning; GATA and IRF1 factors—which were most affected by the stressful conditions in their study—are involved in regulating inflammatory responses and in cell growth and survival. Inflammation and cell death can cause a wide variety of health conditions involving the horse’s organs.

“The transcriptomic approach we have used shows that (a horse’s) living conditions can modify the activation of genes belonging to some molecular regulatory pathways,” Foury said, especially genes targeted by GATA and IRF1, which play important roles in immune function.

“The risk of disease associated with GATA and IRF1 activation is (related to) an increase of certain factors of inflammation, as seen in previous research,” she added.

Foury said further genomic research is necessary to better understand the links between the GATA and IRF pathways modifications and inflammation in the horse.

This study is part of a larger research program focusing on the effects of stress and isolation on horses, led by Lea Lansade, PhD, researcher at the French national stud and in the INRA behavior science department in Tours.

A. Foury, L. Lansade, M. Valenchon, C. Neveux, F. Lévy et M.P. Moisan. Evaluation génomique du stress chez le cheval. 39ème Journée de la Recherche Equine, Paris, 28/2/2013

About the Author

Christa Lesté-Lasserre, MA

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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