10a. Nervous System - Intro Flashcards
What is the nervous system made up of?
Central
Peripheral
What are the key factors affecting NS health?
Lifestyle
Nerve cell structure and function
Hormonal and immune
Energy
GI health
What can affect nerve cell structure and function?
Cell membrane integrity via EFAs
Myelin
AOs
Minerals
Removal of toxins
How can hormonal and immune affect NS health?
Oestrogen
Testosterone
Thyroxine
Cortisol
Adrenaline
Cytokines
Neurotrophic factors
What is the gut brain axis?
Bidirectional communication between the central and enteric NS
What connects the gut and brain in the NS?
Vagus nerve
What is the Vagus nerve made up of?
80% afferent fibres
20% efferent fibres
How do gut microbes interact with the GBA?
Modulates NT production e.g. serotonin
Bacterial metabolites e.g. SCFAs support intestinal barrier
Modulation of afferent sensory nerves
BDNF production
How can gut barrier function influence the GBA?
Compromised mucosal layer
Activation of pathogens and commensals
Increased permeability of the tight junction
Resulting in metabolic endotoxaemia
What can high levels of LPS be lead to?
Neuroinflammation
Depression
What are the key factors influencing general nervous function?
Inflammation
Oxidative stress
Toxic load
Decreased expression of neurotrophic factors e.g. BDNF due to stress, ageing, lack of physical activity
Mitochondrial changes e.g. inflammation, ageing, nutritional deficits
What are neurotransmitters?
Chemical messengers released from a pre-synaptic terminal
Can cause either an inhibitory or excitatory effect on the post-synaptic cell
What can NT imbalances be the result of?
Inadequate nutrition
High stress
Poor digestion health
Toxicity
Drug use
SNPs
What substances does NT synthesis require?
Amino acids
Co-factors - B6
Why is methylation important for NTs?
Methylfolate for biopterin (BH4 - co-factor for serotonin/dopamine)
SAMe for melatonin/adrenaline
How do we get NT balance?
Support reuptake mechanisms
Inactivate and remove used NTs
(enzyme breakdown, diffusion, reabsorption)
What are the key enzymes needed for NT breakdown?
Monoamine oxidase (MAO) - breaks down serotonin, adrenaline, noradrenaline, dopamine
COMT - breaks down adrenaline, noradrenaline, dopamine using a methyl group from SAMe
What is serotonin?
A monoamine NT produced from tryptophan
What is serotonin produced by?
Enterochromaffin cells and bacteria in gut
CNS
What are the functions of serotonin?
GI signalling - motility patterns, epithelial secretions
Mood
Appetite
Sleep (melatonin synthesis)
Blood clotting
What is an indicator of serotonin levels on an OAT test?
5-HIAA
(metabolite of serotonin)
Sequence of tryptophan to melatonin synthesis
Tryptophan - 5HTP - Serotonin - N-Acetylserotonin - Melatonin
Food sources for tryptophan
Bananas
Turkey/chicken
Legumes
Pulses
Fish
Oats
Pumpkin seeds
Rice
Co-factors for conversion of tryptophan to 5HTP
B3, B6
Vit C
Ca
Fe
Zn
D3
5-MTHF
Enzyme for the conversion of tryptophan to 5HTP
Tryptophan hydroxylase
Co-factors for conversion of 5HTP to serotonin
B6
Mg
Vit C
Zn
Enzyme for the conversion of 5HTP to serotonin
Aromatic acid decarboxylase
Co-factor for conversion of serotonin to N-Acetylserotonin
Acetyl-CoA
(B5)
Co-factor for conversion of N-Acetylserotonin to melatonin
SAMe
(5-MTHF, B12)
Causes and risk factors for low serotonin
Insufficient nutrient status
Chronic stress
GI dysbiosis
Poor digestive health
Lack of sunlight
Caffeine
Long-term alcohol use
Being sedentary
Statin use
Heavy metals
Sex hormone imbalances
Deficiency in which nutrients can lead to low serotonin
Tryptophan
Zn
Fe
Mg
B6
B9
What is the mechanism for chronic stress lowering serotonin?
Hyper-secretion of ACTH and cortisol may alter chaperone proteins which maintain 5HT receptor integrity and uptake
What is the mechanism for GI dysbiosis lowering serotonin?
Dysbiosis can impact tryptophan metabolism and gut serotonin which in turn can impact brain serotonin metabolism
How can lack of sunlight lower serotonin levels?
In periods of darkness, more serotonin is used to synthesise melatonin
How does caffeine lower serotonin levels?
Inhibits tryptophan hydroxylase
How does being sedentary lower serotonin levels?
Exercise increases serotonin
How does statin use lower serotonin levels?
Chronic cholesterol depletion using statins impairs the function and dynamics of serotonin 1A receptors
How can heavy metals lower serotonin levels?
Arsenic disrupts serotonin metabolism and can induce neuronal death
Mercury inhibits serotonin receptor binding
How can sex hormone imbalances lower serotonin levels?
Low oestrogen can lower the activity of tryptophan hydroxylase
What is the tryptophan steal?
Enzymes shunt tryptophan to make NAD+ and ATP at the expense of serotonin
Which pathway is used to make tryptophan?
Kynurenine
What can upregulate the tryptophan steal?
Stress
Inflammation
What is the by-product of the conversion of tryptophan to NAD+ via the kynurenine pathway?
Quinolinic acid
What does quinolinic acid do?
Increases glutamate (excitatory)
Hinders neuronal function
Causes cell death
Which conditions is quinolinic acid linked to?
Neurodegenerative diseases
Mood disorders
Natural solutions to lowering quinolinic acid neurotoxicity
Catechins
EGCG
Curcumin
Garlic
Broccoli sprouts
Pomegranate
Saffron
Examples of SNPs associated with low serotonin
TPH1
TPH2
5-HTT
5-HT1
5-HT2A
MAO-A
VDR
What can a SNP on TPH1 result in?
Effects peripheral serotonin synthesis
Constipation (if slow)
What can a SNP on TPH2 result in?
Lower CNS serotonin synthesis
What can a SNP on 5-HTT effect?
SERT transporters
What can a SNP on 5-HT1 and 2A result in?
Reduction in the effects of serotonin
What can a SNP on MAO-A result in?
More enzymatic breakdown and lower serotonin
What can a SNP on VDR result in?
Lower sensitivity to vit D
Less support for serotonin synthesis
Which conditions/disorders is low serotonin associated with?
Mood/Anxiety/Panic disorders
Insomnia
Anger
Eating disorders
OCD
Addictions
IBS/constipation
Migraines
What is glutamate?
Excitatory NT that has a role in memory/learning
What is GABA?
An inhibitory NT
What are the functions of GABA?
Sleep
Relaxation
Co-factors for the production of GABA
B6
Zn
Mg
Vit C
Which conditions is excess glutamate associated with?
AZD
MS
Epilepsy
Signs and symptoms of GABA deficiency
Anxiety
Insomnia
Alcohol craving
Carb craving
Panic attacks
Palpitations
Seizures
Tinnitus
Cold or clammy hands
Which enzyme converts glutamate to GABA?
Glutamate decarboxylase (GAD)
Causes and risk factors for a GABA deficiency
Alcohol - inhibits GAD
Co-factor deficiencies - B6, Mg, Zn, vit C
Dysbiosis
Chronic stress
Limited exercise
Impaired digestion/absorption
How can dysbiosis cause a GABA deficiency?
Several strains of Lactobacillus and Bifidobacterium synthesise GABA and influence Vagus nerve activity
How can chronic stress reduce GABA activity?
Decreased expression of GAD and GABRA2 receptors
Key GABA SNPs
GABRA2
GAD
What does a SNP on GABRA2 do?
Lowers sensitivity to GABA - feels like you have less GABA
What are people with a GABRA2 SNP likely to do?
Misuse alcohol to get the GABA relaxation effect
What does a SNP on GAD1 and 2 do?
Impacts glutamate to GABA synthesis
What are the functions of dopamine?
Motor control
Reward seeking
Motivation
Which hormone does dopamine inhibit?
Prolactin
Which test is best for looking at dopamine levels?
OAT
What is the indicator on an OAT test for dopamine levels?
HVA
Stages to making dopamine/adrenaline/noradrenaline
Phenylalanine - tyrosine - L-dopa - dopamine/adrenaline/noradrenaline
Co-factors in the conversion of phenylalanine to dopamine
B1, B3, B6
Vit C
Fe
5-MTHF
Enzymes needed for the conversion of phenylalanine to dopamine
Phenylalanine hydroxylase
Tyrosine hydroxylase
Signs of dopamine depletion
Rigidity
Tremors
Bradykinesia
What is the drug for treating Parkinson’s?
Levodopa
Which vitamin is contraindicated for anyone on levodopa?
B6
(converts levodopa to dopamine but it doesn’t cross BBB, losing its effect)
Which food ingredient increases dopamine release?
Sugar
Which conditions are low levels of dopamine associated with?
Anxiety/depression
Low libido
Restless leg syndrome
Which conditions are high levels of dopamine associated with?
OCD
Hyperactivity
Causes and risk factors of dopamine imbalances
Insufficient dietary intake of phenylalanine/tyrosine/co-factors
Poor digestion/absorption
Chronic stress - increases adrenaline
Sleep deprivation - downregulates DA receptors
High sugar diets
High saturated fat diets
Recreational drug use
Poor gut health/dysbiosis
Why can poor gut health/dysbiosis lead to a dopamine imbalance?
50% of dopamine produced in GIT
(enteric neurons, epithelial cells, bacteria)
Key SNPs for a dopamine imbalance
TH
MTHFR
COMT
MAOB
What does a SNP on TH do?
Increases TH activity = increased DA
Good for cognition
Bad as could = excess DA
What does a SNP on MTHFR do for dopamine?
Reduces methylfolate which can impact dopamine synthesis
What does a SNP on COMT do for dopamine?
Breaks down DA
Fast COMT lowers DA
Slow COMT increases DA
What does a SNP on MAOB do for dopamine?
Breaks down DA more slowly
What is acetylcholine?
Major NT in the PSNS
Anti-inflammatory in brain
What are the main functions of acetylcholine?
Mood
Memory
Learning
What is acetylcholine formed from?
Acetyl-CoA
Choline (dietary)
What can downregulate acetylcholine?
Cortisol
(inhibits acetyltransferase)
Key food sources of choline
Eggs
Chickpeas
Oranges
Cauliflower
What are the amino acids needed to produce taurine?
Methionine
Cysteine
What are the functions of taurine?
GABA agonist
Glutamate antagonist
What is the co-factor needed to make taurine?
B6