Trusting Your Gut: Lessons in molecular neuroscience and mental health

The bacteria in your gut can talk to your brain.

No, really.

It might sound like science fiction, but you’ve probably heard the phrase ‘gut-brain axis’ used in recent years to describe this phenomenon. What we call the “gut” actually refers to the small and large intestines, where a collection of microorganisms known as the gut microbiome reside. In addition to the microbes that inhabit it, your gut contains around 500 million neurons, which connect to your brain through bidirectional nerves – the biggest of which is the vagus nerve. Bacteria might be able to interact with specialized sensory cells within the gut lining and trigger neuronal firing from the gut to the brain.

Our guest this week is Caroline Hernández, a PhD student in the Maude David Lab in the Department of Microbiology, and she is studying exactly this phenomenon. While the idea that the gut and the brain are connected is not exactly new (ever heard the phrase “a gut feeling” or felt “butterflies” in your gut when you’re nervous?), there still isn’t much known about how exactly this works on a molecular level. This is what Caroline’s work aims to untangle, using an in vitro  (which means outside of a living organism – in this case, cells in a petri dish) approach: if you could grow both the sensory gut cells and neurons in the same petri dish, and then expose them to gut bacteria, what could you observe about their interactions?

Caroline Hernández in her lab at Oregon State, using a stereo microscope to identify anatomical structures in a mouse before dissecting out a nerve bundle

The answer to this question could tell us a lot about how the gut-brain axis works on a molecular level, and could help researchers understand the mechanisms by which the gut microbiome can possibly modulate behavior, mood, learning, and cognition. This could have important implications down the line for how we conceptualize and potentially treat mood and behavioral disorders. Some mouse studies have already shown that mice treated with the probiotic Lactobacillus rhamnosus display reduced anxiety-like and depressive behaviors, for example – but exactly how this works isn’t really clear.

The challenges of in vitro research

Before these mechanisms can really be untangled, there are several challenges that Caroline is working on solving. The biggest one is just getting the cells to grow at all: Caroline and her team must first carefully extract specific gut sensory tissue and a specific ganglion (which is a blob of neurons) from mice, a delicate process that requires the use of specialized tools and equipment. Once they’ve verified that they have the correct anatomy, the tissues are moved into media, a liquid that contains specialized nutrients to help provide the cells with the growth factors they need to stay alive. Because this is very cutting-edge research, Caroline’s team is among the first in the world to attempt this technique – meaning there is a lot of trial and error and not a great amount of resources out there to help. There have been a number of hurdles along the way, but Caroline is no stranger to meeting challenges head-on and overcoming them with incredible resilience.

From art interactions to microbial interactions

Her journey into science started in a somewhat unexpected way: Caroline began her undergraduate career as a studio art major in community college. Her art was focused on interactivity and she was especially interested in how the person perceiving the art could interact with and explore it. Eventually she decided that while she was quite skilled at it, art was not the career path she wanted to pursue, so she switched into science, where she began her Bachelors of Science in molecular and cellular biology at the University of Illinois in Urbana Champaign.

During her undergraduate degree, a mental health crisis prompted Caroline to file for a medical withdrawal from her program. The break was much needed and allowed her to focus on taking care of herself and her health before returning to the rigorous and intense program three years later. Caroline is now a strong supporter of mental health resource awareness – in this episode of Inspiration Dissemination she will describe some of the challenges and barriers she faced when returning to finish her degree, and some of the pushback she faced when deciding to pursue a PhD.

“Not everyone was supportive,” she says. “I didn’t receive great encouragement from some of my advisors.”

Where she did find support and community was in her undergraduate research lab. Her work in this lab on the effects of diet and the microbiome on human health gave her the confidence to pursue graduate school, demonstrating that she was more than capable of engaging in independent research. In particular Caroline recalls her mentor Leila Shinn, a PhD student at the time in that lab, who had a profound impact on her decision to apply to graduate programs.

Tune in on Feb 27th to hear the rest of Caroline’s story and what brought her to Oregon State in particular. You can listen live at 7 PM PST on 88.7 FM Corvallis, online at https://kbvrfm.orangemedianetwork.com, or you can catch the episode after the show airs wherever you get your podcasts.

If you are an undergraduate student or graduate student at Oregon State University and are experiencing mental health struggles, you’re not alone and there are resources to help. CAPS offers crisis counseling services as well as individual therapy and support and skill-building groups.