This document outlines the microbiota-gut-brain axis and its influence on mental health conditions like anxiety and depression. It discusses how gut microbes communicate with the brain through pathways like the vagus nerve, immune system, and neurotransmitters. Certain microbes can produce neurotransmitters like GABA and serotonin that impact brain functions related to mood. Imbalances in the gut microbiome through factors like stress, antibiotics, and diet have been linked to mental health issues by disrupting this axis. Future research aims to better understand these relationships and develop microbiome-targeted treatments and preventions.

2. MICROBES &
MENTAL HEALTH
RANI SUMMEYA SEME 33

3. OUTLINE
• Introduction
• Gut Microbiota
• Microbiota Gut Brain Axis
• Communication pathways & Neurobiological Mechanism
• Neurotransmitter & Neuropeptide
• Influence of Microbioata GBA on Anxiety & Depression
• Gut Microbioata Treatment
• Conclusion & Future Direction

4. INTRODUCTION
• GI------100 trillion MO
Like bacteria, yeast, archea etc.
• Imp in development & functioning
Like digestion, growth etc.
• Role in diseases
Obesity, asthma, diabetes type 2
• Recent studies ----- GBA ---- CNS ----- Neuropsychiatric Disorder
Mechanism ----- not well understood
Research ----- bidirectional communication
b/w GMB & CNS
Anxiety & depression

5. THE GUT MICROBIOTA
• Estimated -----10^14 MO
<10 times somatic/ germ cells
• 3:1 MO to human cell
• 1/3rd GMB common
• 2/3rd individual specific ---- personal identity
• Microbes ---- host metabolic pathways
Fat distribution,
Nutrition absorption
• Host microbes ---- symbiosis
• Dysbiosis ----- mental health

6. Microbiota Gut Brain Axis
• Reciprocal Communication
• Overlapping pathways :-
Neuroendocrine System
Immune System
Autonomic System
Enteric Nervous System
• 2 way information exchange
• GI-----500 million nerve endings & immune cells
• Neuronal & biochemical processes-----GBA
• Dysfunction of GBA
Eating disorder
Stress
Inflammation

7. Communication pathways &
Neurobiological Mechanism
• VAGUS NERVE (X CRANIAL NERVE)
Link b/w GB
• CELL WALL COMPONENT & IMMUNE RESPONSES
Bacterial cell wall activate
Innate Response
Adaptive Response
• METABOLITES
Digestion & MB Fermentation
Imp mediator of GBA

8. CONTINUE…
FATTY ACIDS
• Brain is enriched
• Help on regulation
Neurotransmission
Cell survival
Neuroinflammation
• Production of Eicosanoid----Immune & Inflammatory response
• Regulate gene transcription
• Microbial derived SCFA---- anti inflammatory properties
• Primary metabolite of GB
• Spp. Eubacterium, Bifidobacterium, Enterobacter & Lactobacillus

9. CONTINUE…
• Produces acetate, butyrate, isobutyrtate, isopropionate
• N-butyrate & propionate------neuroactive properties
• Role in Enteroendocrine
TRYPTOPHAN
• Synthesis of serotonin---depression----gut
• Tryptophan & Tryptophan Hydroxylase
• Co-influence of tryptophan & immune system
• CNS function & Mood disorder
• Tryptophan metabolism---- Desregulation ---- Brain & GI disorders

10. NEUROTRANSMITER &
NEUROPEPTIDE
• Produced by bacteria
Lactobacillus
Bifidobacterium
Escherichia
Enterococcus etc.
Neurotransmitter
chemical messenger--- transmit signal---synapse
Neuropeptide
protein--- released in brain---activate receptors--- neuron to communicate
• Neuronal signaling messenger
• Imbalances effect Brain & Behavior

12. CONTINUE…
GABA
• Inhibitory neurotransmitter
• Produced by Glutamate metabolism
• Dysfunction----Chronic Disease
Anxiety
Depression
• Bifidobacterium & Lactobacillus----produces GABA from Glutamate
• L.rhamnosus---modulate expression of GABA in CNS
• Treatment of depression & anxiety
• Vagus Nerve-----necessary
• Behavioral & Molecular changes

13. CONTINUE…
SEROTONIN
• Monoamine Neurotransmitter
• Regulate all brain functions
• Modulate physiological processes
Mood
Sleep
Pain
Aggression,
• Dysregulation-----Neuropsychiatric Disorders
Anxiety & Depression
• 90% produced-----enterochromaffin cell in GI
• Spp. Of Escherichia & Enterococcus
Directly influence CNS function

14. CONTINUE…
BDNF
• Neurotrophin-----CNS
Survival of existing neuron
Encourages growth
Differentiation of Neurons & Synapses
• Decreased level----chronic depression
• mRNA & protein level associated with GBA
• Intestinal microbioata-----increases BDNF
• In mice infected with
Truchuris muris-----decreased level of BDNF
B. longum-----BDNF level normalized

15. INFLUENCE OF MICROBIOATA GBA ON
ANXIETY & DEPRESSION
Anxiety
‘‘ Psychological state characterized by apprehension or fear. ’’
Depression
‘‘Medical illness that negatively affects how you feel, the way you think and how you act.’’
More than 350 million suffer
Contribute to
Loss of productivity
Increase Annual health care cost
Economic burden to public health care system
• Etiology of disorders unknown

16. CONTINUE…
• Proposed Neurobiological Mechanisms
Chemical imbalance
Illness
Inflammation
Reduction in Neurotransmitters
Change in Neuroendocrinal Pathways & Hormones
Stress
Autonomic Nervous System (ANS)
Complex interaction with metabolism
Pro- & Anti-inflammatory components of immune system
• Gut MB role in treatment & prevention

17. CONTINUE…
Microbes & Stress
Research from Neurobiology & Microbiology
Natural barrier defenses----- disturbed by exposure to biological stressors
Eg study by Tannock & Savage 1974
Moving mice----- cage
Lacking bedding, food, water---reduced number of Lactobacilli
Potential cause----novel housing
Influence of Psychological stressor on Microbial Health
Infant rhesus monkey-----mother separation(stressor)
Lowered cultured Lactobacilli
Microbiome of organism exposed to stressor differed from non stressed organism

18. GUT MICROBIOATA TREATMENT
• Probiotics
‘‘Living MO that believed to provide health benefits when consumed.’’
Lactobacillus & Bifidobacterium
Alter composition & diversity of GMB
• Antibiotics
Antibacterials
Used in treatment & prevention of bacteria
Effect microbiota GBA
Eg mice---antibiotics---7 days
Reduced anxiety like & increase exploratory behavior
• Transplant
FMT---effective

19. CONCLUSION & FUTURE DIRECTION
• Early stage of understanding
• Microbe play imp role in
Immune function
Stress responding
Brain function and behavior
• Stress affect composition of GMB
• Various treatment alter GMB---behavior & health outcome
• These studies----innovative approach---prevention & treatment of disorders
• Future work---elucidate---interceptive connection
• Advancement in brain based disorders