Stress Response

While plenty of research has been conducted on how maternal stress during pregnancy can affect offspring, little is known about the impact of stress during lactation. Researchers at the University of Idaho are using epigenetics — the study of how behaviors and environment can cause changes that affect the way genes work — to start the conversation.

Impacts of Stress

Emma Sells, a senior studying animal and veterinary science pre-vet option, is working with Amy Skibiel, assistant professor of lactation physiology, and Chloe Josefson, postdoctoral fellow, to investigate how maternal stress during lactation impacts the ability of offspring to mount a stress response when they are matured, and the long-term impacts on fitness.

“Nobody has really done research on the stress response during lactation,” Sells said. “All of the papers we’ve been able to find have been while the animal was pregnant. So, this is a different viewpoint because it allows that extended time in which the mother can impact her offspring.”

The project began in summer 2020 when lactating rats were exposed to unknown male rats. A male was put in a cage with a female and her offspring, or pup, for an hour each day for nearly two weeks to cause stress in the female.

Sells is now analyzing liver samples taken from the pups using bisulfite sequencing to determine patterns of DNA methylation. Methylation is a common mode for epigenetic modification, allowing gene expression to be changed without manipulating the actual genetic sequence.

“We want to see how methylation rates differ in offspring whose mothers were stressed during lactation and offspring whose mothers weren’t to see if they express stress-related genes differently,” Sells said.

Sells is focused on two main genes, MR (mineralocorticoid receptor) and GR (glucocorticoid receptor). MR is an intracellular steroid hormone receptor and GR regulates genes controlling development, metabolism and immune response.

“These are important in the stress response for vertebrates,” Sells said. “They regulate the ability of the animal to maintain a good stress level during their life, and also respond appropriately during a stressful situation. We want to see if these two genes are turned on or off as a result of maternal stress during lactation.”

Since little research exists on the topic, the team is focused on developing protocols that will support future research.

“It’s a very first-time experiment for us,” Sells said. “We’ve never done bisulfite sequencing in our lab so we’re really working on the protocol. If we can understand how stress early on in life can impact the animal in the future, we can predict how their physiology might change and where they might have problems.”

Future Veterinarian

Originally from Meridian, Sells decided to seek out undergraduate research opportunities to prepare her for veterinary school. She will begin the WIMU Regional Veterinary Program at Washington State University in fall 2022 while finishing her bachelor’s at U of I.

“I would encourage anyone to do undergraduate research,” Sells said. “I came into it very much wanting to build my resume, but I wouldn’t trade it for the world. It’s been an incredible experience to get those hands-on skills and discover what you’re really passionate about.”

Sells will continue working in Skibiel’s lab during summer 2022 as an Idaho INBRE Undergraduate Fellow. That project will focus on how maternal immune responses during lactation impacts the spread of antibodies to male offspring and subsequent effects on their reproductive performance.

Eventually, she hopes to become a large animal veterinarian with a focus on dairy cattle.

“Dairy is such an integrated part of agriculture and I think it’s more important than a lot of people realize,” Sells said. “I always wanted to do something in my career that allows me to promote agriculture. So, I thought being a veterinarian and being able to specifically work with dairies would be a great way to continue to promote that because there are so many misconceptions out there.”

The hands-on experiences she has gained at U of I through undergraduate research and classes helped affirm her future career goals.

“During spring my freshman year, I went to the dairy and helped with muscle and liver tissue biopsies,” Sells said. “That was a time when I was really thinking about vet school and not sure if that was a path I really wanted to do. Getting that hands-on experience with animals that I hadn’t had before was incredible. It really gave me clarity in my career path that this was what I wanted to do and those are the animals I want to work with.”

Article by Amy Calabretta, College of Agricultural and Life Sciences

Published in May 2022