NT Flashcards
Criteria to be a Neurotransmitter
Must be present within pre-synaptic neurons
Must be released in response to pre-synaptic depolarization (release is Ca+2 dependent)
Specific receptors for the transmitter must be present on the post-synaptic neuron
Types of NT
Small Molecule NTs -Other NTs -Amino Acid NTs -Monoamine (Biogenic Amine) NTs -Other Monoamine NTs -Catecholamine NTs Peptide NTs
Other NT
Acetylcholine
Acetylcholine
Type: small molecule Broken down in the synaptic cleft Nicotinic receptors Excitatory ionotropic receptors Muscarinic receptors Some excitatory and some inhibitory metabotropic receptors
Acetylcholine and Brain Function
Cognition
Attention
Learning
Memory
Implicated in aging
Acetylcholine neurons die in Alzheimer’s disease
Amino Acid NTs
Glutamate
γ-aminobutyric acid (GABA)
Glutamate
Type: Small molecule
Broken down within the pre-synaptic terminals
NMDA receptors (N-methyl-D-aspartate) Excitatory ionotropic receptors AMPA receptors (α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate) Excitatory ionotropic receptors Kainate receptors Excitatory ionotropic receptors mGluRs Some excitatory and some inhibitory metabotropic receptors
Glutamate and Brain Function
Most widely used excitatory NT in the brain
At most excitatory synapses
γ-aminobutyric acid (GABA)
Type: Small molecule Broken down in mitochondria in presynaptic terminal GABAA receptors Inhibitory ionotropic receptors GABAC receptors Inhibitory ionotropic receptors GABAB receptors Inhibitory metabotropic receptors
GABA and Brain Function
Commonly found in local circuit interneurons
GABA fine-tunes other systems in the brain
Monoamine NT
Serotonin
Histamine
Serotonin and Brain Function
Important for eating behavior
Involved in mood regulation and mood/anxiety disorders
Histamine
Type: Small molecule
Broken down within the pre-synaptic neuron
Metabotropic receptors
Some excitatory and some inhibitory metabotropic receptors
Histamine and Brain Function
Sleep/wake cycles
Diffuse projections around the brain promote wake
Catecholamine NT:
Dopamine
Norepinephrine
Dopamine
Type: small molecule
Transporter: dopamine transporter (DAT), takes dopamine up from the synaptic cleft into the pre-synaptic neuron
Degraded in the pre-synaptic neuron by monoamine oxidase (MAO)
Metabotropic receptors
Some excitatory and some inhibitory metabotropic receptors
Dopamine and Brain Function
Movement
Parkinson’s disease
Motivation and reward
Motivated behavior
Drug abuse
Psychiatric disorders
Schizophrenia
Norepinephrine
Type: small molecule
Precursor: dopamine
Transporter: norepinepherine transporter (NET), takes norepinephrine up from the synaptic cleft into the pre-synaptic neuron
Degraded in the pre-synaptic neuron by monoamine oxidase (MAO)
Metabotropic receptors
Some excitatory and some inhibitory metabotropic receptors
Norepinephrine and Brain Function
Sleep/wake patterns
Feeding behavior
Anxiety and affective disorders
Increases during stress and anxiety
Causes peripheral feelings of stress and anxiety
Peptide NT: Opioids
Type: peptide Three classes of opioid NTs: Endorphins Enkephalins Dynorphins Metabotropic receptors All inhibitory metabotropic receptors
Opioids and Brain Function
Body’s “natural drug”
Implicated in drug abuse
Morphine and heroin bind the μ-opioid receptor with high affinity
Many drugs other than opiates activate the opioid system through downstream mechanisms
