Lecture 6 Flashcards
What are believed to be the methods of communication between the brain and the microbiota?
Two way communication occurs efferent nerves such as the adrenergic nerve is activated by stress and communicates by releasing stress hormones like noradrenaline into the gut lumen which may change gene expression or inhibit/promote the growth of certain bacteria
The vagus nerve acts as an afferent nerve sending signals to the brain about the microbiome
There can be a leaky gut which allows bacteria and bacterial products to pass through to the blood
There can also be immune responses or enterocyte endocrine cell signalling
How does the microbial status of mice affect their behaviour and function?
Germ free mice exhibit an exaggerated stress response which could be remedied by inocculating the mice with Bifidobacterium longum but only if this inocculation occured before maturity
What influence on brain activity has bacteria been evidenced to have in healthy humans?
When several humans were given a diet which included 5 probiotics their results on an emotive stress test they had reduced emotion-evoked responses and attenuated responses to emotional tasks
What is a common feature among many people with autism spectrum disorder and the gut?
There is a high prevalence of gastrointestinal problems leading to suggestions of leaky gut and or gluten-casein intolerance
There are also clear differences in the microbiota of those with autism and those without autism but no clear pattern in the differences and this is still highly debated
What is the maternal immune activation model?
A mouse model of autism which is based on the correlation between autsim and viral infection in the first trimester of pregnancy, where there is a viral mimic injected into pregnant mice causing their offspring to display the autistic symptoms of increased anxiety and repetitive behaviour and reduced social interactions
What kind of gut do MIA mice exhibit?
They have an altered bacterial community and a reduced intestinal integrity as well as differences in blood serum metabolites
What was the advantage of inocculating MIA mice with Bacteroides fragilis?
It was found to reduce autistic behaviour in mice leading to decreased anxiety and gut permeability
Certain serum metabolites were reduced or increased following the addition of Bacteroides fragilis including one involved in tryptophan
