How Microbes Influence the Brain.This presentation shows gut brain axis and neurological disorders caused by microbes in gut

1. Neuro-microbiology: How
Microbes Influence the Brain
Presented by – Antra Sood
Student –M.Sc in microbiology
D.A.V University ,Jalandhar

2. The Gut-Brain Connection
Have you ever had a gut
feeling or butterflies
in your stomach?
The gut microbiota
may play a key role
in many essential
processes in health
and disease via the
activity of the gut-
brain axis.
This possibly
contributing to
1-Alzheimer’s
disease,
2-Parkinson’s
disease,
3-depression,
and anxiety
disorder.

3. The composition of the
microbiota evolves over time,
which may have implications
in brain development.
The activity of
microorganisms present in
the intestinal microbiota also
influences the intestinal
immune system, which is
linked to the nervous system

4. The Vagus Nerve and the
Nervous System
Neurons are cells found in your
brain and central nervous system
that tell your body how to
behave. There are approximately
100 billion neurons in the human
brain .
The vagus nerve is one of the
biggest nerves connecting your gut
and brain. It sends signals in both
directions.
This suggests that the vagus nerve
is important in the gut-brain axis
and its role in stress.

5. Neurotransmitters
 Your gut and brain are also
connected through chemicals called
neurotransmitters.
 Neurotransmitters produced in the
brain control feelings and emotions
 Interestingly, many of these
neurotransmitters are also produced
by your gut cells and the trillions of
microbes living there. A large
proportion of serotonin is produced
in the gut .
 Your gut microbes also produce a
neurotransmitter called gamma-
aminobutyric acid (GABA), which
helps control feelings of fear and
anxiety .

6. The communication system between your gut and brain is
called the gut-brain axis.

7. What Foods Help the Gut-Brain Axis?
A few groups of foods
are specifically
beneficial for the
gut-brain axis.
•Here are some of the most important ones:
•Omega-3 fats: These fats are found in oily fish and also in high
quantities in the human brain. Studies in humans and animals show
that omega-3s can increase good bacteria in the gut and reduce risk
of brain disorders.
•Fermented foods: Yogurt, kefir, sauerkraut and cheese all contain
healthy microbes such as lactic acid bacteria. Fermented foods
have been shown to alter brain activity.
•High-fiber foods: Whole grains, nuts, seeds, fruits and vegetables all
contain prebiotic fibers that are good for your gut bacteria.
Prebiotics can reduce stress hormone in humans .
•Polyphenol-rich foods: Cocoa, green tea, olive oil and coffee all
contain polyphenols, which are plant chemicals that are digested by
your gut bacteria. Polyphenols increase healthy gut bacteria and
may improve cognition.

8. Neurological disorders

9. The microbiota can beneficially influence
neurological disorders through endocrine and
neural communication.
The microbiota
can beneficially
influence
neurological
disorders through
endocrine and
neural
communication.
An example of such
gut-brain interaction
and modulation of
cellular processes is
the ability of
bacteria to
synthesize and
release
neurotransmitters,
which may interact
with enteric and
endocrine cells.
The gut
microbiota also
appears to play
other roles, such
as modulating the
immune response
of the intestinal
mucosa during
infection,
inflammation, or
autoimmunity.

10. Alzheimer’s Disease

11. Alzheimer’s Disease
is a neurodegenerative
disorder with complex
aetiologies that are still
poorly understood.
The severe cognitive impairments
associated with AD correlate with
the accumulation of protein
aggregates composed of amyloid
plaques (amyloidosis) and tau
protein tangles in tissues of the CNS.

14. Another association study identified more inflammation-
associated bacteria, such as Escherichia and Shigella, in
faecal samples from AD patients compared to control
groups, which correlated with increased levels of pro-
inflammatory cytokines (e.g., IL-1β) in the blood.
Further supporting the link between AD and bacteria,
intestinal permeability increases with age, thereby allowing
bacteria to translocate from the lumen of the gut and
mediate neuro-inflammation.

15. Risk factors
There are a number of characteristics and conditions that can increase one’s chances of
developing Alzheimer’s; however, It should be noted that the presence of one or more of
the following factors does not necessarily mean that the disease will manifest.
Age
The likelihood of developing AD doubles every 5 years after reaching the age of 65, a
point of major concern, as this age group is the fastest growing with the increase in
longevity and the shift of the Baby Boomer generation into older age.
Environmental
Exposure to high amounts of certain metals, air pollutants, nutrition, various pesticides,
and stress have been linked to AD.
Family history
Individuals with one or more relatives with AD are more likely to develop the disease, due
to heredity and/or environment.
Genetic
There are genes that increase one’s risk of developing Alzheimer’s by facilitating the
formation of longer- form amyloid beta peptide plaque clusters between nerve cells, the
presence of which is believed to result in neurodegeneration. The genes are as follows;
Apolipoprotein E 4 (ApoE-ε4), Amyloid precursor protein (APP), Presenilin-1 and 2 (PS-1
and PS-2).
Head Trauma
Those with a history of head trauma are 4.5 times more likely to suffer from AD than
those without. This has to do to with the chemical changes that may occur as a result of
brain injury.

17. Parkinson’s Disease

18. Parkinson’s Disease
is a neurodegenerative
motor disorder that
affects an estimated 1
million people and 1% of
the United States
population > 60 years of
age. PD is commonly
associated with impaired
gastric motility(58) and
elevated levels of alpha-
synuclein in the intestine.

20. What are Common Risk Factors for
Parkinson’s?
 Gender
 Age
 Ethnicity
 Family history and genetics
 Head Trauma
 Environmental pesticides

21. DEPRESSION
 Depression, the most common
mental disorder, is a
multifactorial disease that can
result from biological,
psychological, and social
factors
 A link between depression
and the microbiota has
been established by
research with mouse models.
GF mice, lacking a normal gut
microbiota, display less of the
behavioural impairment
associated with depression and
anxiety than mice having a
microbiota

22. Using clinical samples, It
was found that patients
with major depressive
disorder displayed
differences in the relative
abundance of Firmicutes,
Bacteroidetes,
and Actinobacteria when
compared with healthy
individuals.

23. Anxiety Disorder
 Anxiety disorder is characterized by behavioural
disturbances, phobia, and panic syndrome, as well as
fear.
 Anxiety can also be understood as social phobia,
which consists of fear in social situations that
interferes directly with social conviviality
 Because microorganisms can act within the autonomic
nervous system, as well as in the HPA axis, changes in
alimentary behavior may have consequences for anxiety
disorder.

24. Lactobacilli and Bifidobacteria have
shown therapeutic potential in the
context of neurological disorders,
including anxiety.
Lactobacillus can improve symptoms
associated with anxiety in patients
with chronic fatigue syndrome.

25. Conclusion
 The gut microbiome plays a significant role in the health and disease
states of the host, much of the research done to date on this topic has
only demonstrated associations between bacterial profiles and certain
clinical conditions.
 A great deal of the work so far has involved comparisons between GF
mice and mice having a microbiota. Such comparisons have been
useful to establish behavioural and neurological distinctions between
these populations but, nevertheless, represent an extreme “all or
nothing” scenario
 There is substantial evidence to suggest that probiotics may offer
approaches to improving the health of individuals with neurological
disorders.
 The molecular mechanisms regulating the relationships between
microbiota and the brain need to be understood in much greater
depth before probiotics can begin to be developed as targeted
therapeutics.

26. References and bibliography
 Neuromicrobiology: How Microbes Influence the Brain,Cesar de la Fuente-
Nunez, Beatriz Torres Meneguetti, Octávio Luiz Franco, and Timothy K. Lu
 Google images
 https://www.healthline.com/nutrition/gut-brain-connection#section3
 http://www.assignmentpoint.com/science/biology/about-
neurotransmitter.html

27. THANKYOU