neurotransmitters in depression Flashcards
areas of brain that are particularly affected?
basel ganglia
neocortex: prefrontal cortex
limbic system
deep brain stimulation of the subthalamus (limbic system) in depression (link with mood)
mood changes in positive direction, but lower mood also reported
main functions of limbic system
emotion
motivation
memory
neuro transmitters - where is information received?
dendrites –> axon –> terminal buttons
synapse at synaptic cleft
what are the types of neurotransmitters?
inhibitory
excitatory
ion channel
second messenger
what are the 2 main neurotransmitters for depressive disorders?
noradrenaline
serotonin
other neurotransmitters important in psychiatric conditions?
dopamine
acetylcholine
GABA (alcohol)
glutamate
NA function in the brain?
mood
suggests a role in behaviour (arousal and attention)
implicated in memory functions
where is NA made? transported to?
made in locus coeruleus in the brainstem and transported to several areas of the cortex
receptors for NA?
4 types: alpha 1 + 2, ß1, ß2
alpha receptors play role in arousal and mood
NA synthesis?
tyrosine – (tyrosine hydroxylase)–> dopa – (AA decarboxylase)–> dopamine – (dopamine ß-hydroxylase)–> NA –> adrenaline
evidence of NA being implicated in causation of depression?
AMPT inhibits tyrosine to L-DOPA:
increase sleep, anger, depressive symptoms
decrease calmness
anti-depressants?
NARI (NA reuptake inhibitor):
TCA (tricyclic anti-depressants)
SNRI’s
effects of other substances e.g. reserpine?
depletes the nerve ends of NA
role of serotonin in the brain?
sleep
impulse control
appetite
mood
where is serotonin produced? transported?
produced in brain stem (Raphe nuclei) and transported to cortical areas and limbic system
serotonin synthesis?
tryptophan (AA) –> 5-HTP –> serotonin –> N-acetyl serotonin –> melatonin
serotonin receptors?
complex, many different pre + post serotonergic receptors
reasons for implicating serotonin (5HT) in depression?
5HIAA depletion in CSF in patients with depression (metabolite of serotonin)
tryptophan depletion (precursor for serotonin) causes depression
PET + SPET studies
reserpine
anti-depressants?
SSRI (serotonin reuptake inhibitor)
TCA
SNRI’s
MAO-I
dopamine and depression?
3 main pathways
role in parkinson’s disease (40% PD pts have depression)
release gives pleasure feeling (cocaine + amphetamines)
HVA low in patients with depression
role in ‘drive’
ECT has effect on dopamine system
effects of anti-parkinson’s medication
main neurotransmitted implicated in schizophrenia
mono-amine hypothesis of depression focuses on the role of?
serotonin
NA
dopamine
neurotransmitter changes in mania?
NA increased in manic phrase in BPM patients
serotonin findings inconsistent
antipsychotics block dopamine and have anti-manic (and depressive) properties
dopamine agonists can cause main symptoms
mood stabilisers?
lithium: classical mood stabiliser
exact mechanism unknown
positive effect on BDNF transcription
possible positive effect on serotonin production
What is GABA?
most important inhibitory neurotransmitter in the brain
GABA (A) and GABA (B) receptors
several chemicals affect the chloride permeability of the membrane
affinity for alcohol, benzodiazepines and steroids
GABA (A) receptors?
ion channels:
if the receptor is activated, the membrane permeability for chloride increases and this has an inhibitory effect on the neuron
GABA (B) receptors?
second messenger receptors (e.g. GPCR)
