3. Neurotransmitters Flashcards
Neurotransmitters
chemical substances that move messages across the synapse. More than 100 substances.
What are the functions of neurotransmitters?
excitatory or inhibitory depending on their receptor (there are many subtypes that may have very different responses)
what are small-molecule neurotransmitters?
amino acids
monoamines
acetylcholine
Unconventional neurotrasmitters
neuropeptides
pituitary peptdes hypothalamic peptides brain-gut peptides opioid peptides miscellaneous peptides
what are the most common amino acids?
amino acids
excitatory neurotransmitters that are amino acids
glutamate and asparate
inhibitory neurotransmitters that are amino acids
Gamma-aminoburytic acid (GABA) and glycine
how are amino acids distributed
widely through the CNS
Glutamate involved in…
especially involved in learning through a particular receptor-type (NMDA receptors). Involved in excitoticity - prolonged depolarisation of postsynaptic cell -> neuron death
two classes of monoamines
catecholamines and indolamines (based on structure)
Most of them diffusely released into extracellular fluid
catecholamines
dopamine, epinephrine, norepinephrine;
All derived from one amino acid - tyrosine
indolamines
Serotonin or 5-HT (melatonin)
derived from tryptophan
two pathways of dopamine
two pathways are mesostriatal and mesolimbocortical
functions of dopamine
reward (motivation) pleasure, euphoria motor function (fine tuning) compulsion Perservation
Mesostriatal pathway
Dopamine from the substantia nigra to the striatum
mesolimbocortical
from the VTA to the hippocampus, nucleus accumbens and frontal cortex
behavioural effects of serotonin
mood perception memory anger aggression fear stress responses appetite addiction sexuality sleep cognition
seratonin pathway
Raphe nucleus to the striatum, nucleus accumbens, frontal cortex, hippocampus,
what was the first neurotransmitter to be detected?
acetylcholine (ACh)
What is acetylcholine usually referred to as?
the cholinergic system (i.e. acetylcholine-containing)
what are ACh receptors usually?
either nicotinic or muscarinic
nicotinic
ionotropic; excitatory
muscarinic
metabolic; both excitatory and inhibitory
what is Acetylcholine implied in?
Alzheimer’s disease; learning and memory