SUMMARY: This paper reviews the studies looking at the connection between serotonin production, microbiome, and autism. The first two sections give some basic information on serotonin, its reuptake transporter, and the gut-brain connection. Sections three and four talk about changes in serotonin (either reuptake or production) and its connection to the gut microbiome. Section three talks mostly about a genetic component to autism. A variation of the gene that codes for serotonin reuptake transporters is correlated to some autistic behaviors. In section four, metabolites of the gut microbiota is suggested to change the production of serotonin in the intestines. At the end, the authors talk about the various environmental factors (such as maternal infections during pregnancy) that are associated with changes in gut microbiota.
LESSON COMMENTS: This paper covers a lot of topics. In section 2, page 3, the authors talk about why serotonin reuptake transporters are needed to move serotonin through the cell membrane (because serotonin is charged and can’t move across the membrane by itself). This is a good way to examine the molecular structure of serotonin to determine why it is charged and compare it the structure of a phospholipid. Teachers can then tie this to other examples in biology, such as why neurons have specific gates for K+ and Na+. I would introduce this concept after students have learned about ionic compounds.
The third section of the paper is a good way to show students the connection between genes and enzymes, mutations in genes, the effects of mutations on enzyme function, and larger body systems or functions (such as peristalsis) affected by mutations. Section four ties in microbiota metabolites to transcription. This section also addresses the connection between the mother’s immune system, her gut microbiota, and any inherited mutations that then affects the child’s gut microbiome.
Israelyan, N., & Margolis, K. G. (2018). Serotonin as a link between the gut-brain-microbiome axis in autism spectrum disorders. Pharmacological Research,132, 1-6. doi:10.1016/j.phrs.2018.12.023