Gut-Brain Axis Flashcards
Neuropsychiatric disorders include
mood thinking or behavioral disorders
Disorder vs disease
disorder - no lab test
disease - is a test
Clear examples of altered brain function by infections
The gut-brain axis
a bidirectional link between
the CNS and the gastrointestinal track, mediated by
endocrine,
immune,
and neural signaling
microbiota
all the microorganisms living in stable association with their host (i.e. the intestines)
- 10 times more than human cells - misconception actually 2 – 3 times more in a healthy individual - depends on nutritional status of person - hygiene hypothesis
Disruptions to composition associated with allergies and metabolic disorders
hygiene hypothesis
too clean - not being exposed to things anymore
microbiome
genetic content (DNA) - sequenced – can see everything present (inc. viruses, parasites, fungi)
many thing in gut cannot grow in-vitro
Gut – immune link
acquisition of microbiota during birth essential to train immune tolerance - microbial signature of baby
(twins - can predict disease development based on early changes in microbiota)
The vagus nerve
the 10th cranial nerve; longest nerve in the autonomic nervous system (PNS), connecting the GI tract to the brain stem
Bacterial mediators
produce precursors to (ex. tryptophan - GABA), or actual, neurotransmitters (serotonin)
The hypothalamic-pituitary-adrenal (HPA) circuit
the brain’s stress response system
response to external stress (ex. hunger)
response has efect on microbiota
Bacterial metabolites act upon all the different interfaces in the gut:
the epithelial
the immune
the neural
pathology of gut brain axis
pathology of gut brain axis before and after response from brain
Gut brain axis balanced state
Balance of pro- and anti-inflammatory cytokines
Balanced state: the epithelial and immune cells are “trained” in tolerance to “correct” microbiota AND microbiota is “adapted” to host’s biochemical “normal” response
Gut brain axis unbalanced state
Unbalanced state: small change in either microbiota composition or host’s biochemical response can lead to uncontrolled dysregulation (butterfly effect), leading to pathology
Gut brain axis in disease
autoimmune diseases
autism
depression and anxiety
obesity
Gut brain axis in autoimmune dieseases
hygiene hypothesis - destroy period of immune training (farm animals - antibiotics, hormones; homes - so clean)
Immune system training disrupted
Aberrant immune reactions (asthma, allergies, MS) [b/c immune response b/c changes in biota]
Gut brain axis in autism
Correlation between autism and dysbiosis of the gut
Picky eating habits, genetics, or environmental factors, not clear (controversial - cause vs consequence)
Gut brain axis in depression and anxiety
High correlation between intestinal disorders and mental illness
can use antidepressants to treat IBS - brain response - effect on body
Gut brain axis in obesity
Correlation between gut microbiota and misregulation in the CNS control of food intake
altered micobiota - blocks CNS response that makes feel full
ex. bactera change and brain disturbances
Ways the gut brain axis can affect health/disease
- Gut microbiota dysbiosis (many things can cause, hunger, fear etc.)
- Inflammation (infection can cause)→ leaky gut
- Leaky gut → (antigen from gram neg bacteria) LPS exposure → inflammation
- Chronic stress → High cortisol levels
- High cortisol → go back to (1) and (2)
Gut brain axis what causes what
PD and gut-brain axis
GI infection - protect by producing alfa -syn - can be prion like - go from gut to brain
alfa-syn found many places outside the brain
AD and gut-brain axis
brain microbiome project - sequence everything in brain - AD all sours of viruses etc. healthy brains not have
short term: infect - die - accumulation of placks - infect and not die - may be beneficial
Any protein with ability to aggregate and grow plaques can (in theory) be
antimicrobial
However, if over generated or for a long time still results in pathology - a type of dysregulated innate immune response
how aggregates can be protective / antimicrobial
the third brain
where is third brain coming from
___ highlights the connection between mental health and physical health!
MNS umbrella
NTs - fuel for brain - microbes in gut produce same brain fuel - connection - cause vs consequence question
