(Or Time for a Halloween Post: How Microbes Shape Behavior)
A couple weeks ago I volunteered with the UBC Let’s Talk Science Team for a Zombie-Themed Science Day at Science World. I did not know about the Let’s Talk Science (LTS) Organization until I came to Canada. LTS STEM* volunteers create and share exciting science-focused learning programs. For more information about LTS check the link below. And if you are a student or teacher in a STEM program I encourage you to volunteer with LTS!
Our team discussed brain anatomy with young Science World visitors–we even got to decorate awesome brain-shaped cookies. Plus, we received complimentary zombie make-up for the day! Working at Science World reminded me about Amazonian zombie ants. When Cephalotes atratus ants get infected with the Cordyceps fungus, the insects begin displaying fatal, zombie behavior. Cordyceps spores infiltrate the ant brain and force the ant to climb nearby plants and stay put. The ant eventually dies and “a vigorous, silky, greyish-white mycelium* emerg[es] from the body joints and orifices” (Sampson and Evans, 1982). The Cordyceps are now in the perfect position to release ‘zombie’ spores, which drift down and infect more unsuspecting ants.
Did you know that microbiome communities can also shape behaviors? Researchers at the Karolinska Institutet in Sweden found that germ-free mice, which lack a gut microbiota (or any microbiota for that matter!) exhibited increased activity and less anxiety-like behavior compared with mice exposed to microbes. Moreover, researchers discovered that the germ-free mice showed elevated levels of important neurotransmitters, including serotonin and dopamine. Another research group at McMaster University in Canada found that antibiotic-treated mice displayed increased exploratory behavior. Very odd, considering that mice are neophobic (afraid of new things). The antibiotics had altered the gut microbiota composition. When mice were taken off antibiotics, the gut composition and strange behavior returned to normal. Researchers noted that the mice treated with antibiotics also displayed a decrease in brain-derived neurotropic factor, or BDNF. BDNF is a protein that promotes neuron growth and is important for memory and learning. Researchers think that shifts in microbial composition impacted BDNF levels, which changed mouse behavior. Complicated, right?
Lastly (for this post), a recent Bioessays review article discussed whether our gut microbiota manipulates dietary cravings in order for us to eat (unhealthy?!) foods that promote microbial fitness. But feeding gut microbes high-fat and high-sugar treats doesn’t help our waistline! Describing the study, one journalist asked “Are we food zombies controlled by our gut bacteria?” I’m not sure, but maybe that is why I’m craving some Halloween goodies…
Stay tuned for more gut-brain research!
*Science Technology Engineering and Mathematics
**a mass of filamentous-like structures (the vegetative fungal growth)
Sources + Additional Information
Zombie Ants, Anyone? http://www.sciencedirect.com/science/article/pii/S0007153682800375
Germ-free mice: http://www.pnas.org/content/108/7/3047.long
Antibiotics and Microbes: http://www.ncbi.nlm.nih.gov/pubmed/21683077
(Thanks EY for the cookies!)