SUMMARY: This study looked at the effects of Lactobacillus rhamnosus on GABA receptors and the role of the vagus nerve in the gut-brain connection. Results showed that L. rhamnosus decreased cortisone levels in stressed out mice and also changed the expression of GABA receptors. Due to GABA having multiple functions, GABA receptors in different parts of the brain have different functions and effects on the mice. Researchers in this study looked at GABA receptor protein mRNA to determine whether or not they were being upregulated or downregulated. Finally, researchers observed that L. rhamnosus did not affect mice behavior when vagotomies were performed (cutting the vagus nerve). This implicates that the vagus nerve is partially responsible for sending messages from the gut to the brain. The animals used in this study were healthy animals, not germ-free or ones that had been treated with antibiotics.
LESSON COMMENTS: Topics that are covered in this article include: protein synthesis, neurotransmitters, action potential, neurotransmitter receptors, receptor and ligand, cortisone, hormones and homeostasis, and different parts of the brain. This is a good article for students to read (I would suggest teachers summarize the results for the students and highlight certain passages) after learning about the process of protein synthesis.
Bravo, J. A., Forsythe, P., Chew, M. V., Escaravage, E., Savignac, H. M., Dinan, T. G., . . . Cryan, J. F. (2011). Ingestion of Lactobacillus strain regulates emotional behavior and central GABA receptor expression in a mouse via the vagus nerve. Proceedings of the National Academy of Sciences,108(38), 16050-16055. doi:10.1073/pnas.1102999108