Neurotransmitters and Receptors Flashcards
Define neurotransmitters
Chemical messengers that enable neurons to send signals to other neurons
4 criteria for classifying neurotransmitters
- Must be synthesized in presynaptic neurons
- Must be stored in vesicles in presynaptic neurons
- Must be released from presynaptic neuron axon terminal when an action potential is fired
- Must affect the postsynaptic neuron the same way, whether it’s released from presynaptic neuron or applied experimentally
3 examples of amino acid neurotransmitters
Glutamate, glycine, GABA
5 examples of monoamine neurotransmitters
Serotonin
Histamine
Dopamine, norepinephrine, epinephrine (catecholamine)
4 types of endogenous neuroactive substances that are not considered neurotransmitters
Neuromodulators (e.g. adenosine)
Neurotrophic factors
Neurohormones
Gasotransmitters
Which of the classes mediates most of the fast inhibitory/excitatory functions in the brain?
Amino acids
Which of the classes consists of the largest neurotransmitters?
Neuropeptides (endorphins, orexins, substance P)
Which 2 of the small molecule neurotransmitter classes have rings in their structures?
Monoamines and catecholamine
Major excitatory and inhibitory amino acid neurotransmitters
Glutamate: excitatory
GABA: inhibitory
2 key roles of Astrocytes when it comes to GABA and glutamate
- Supplying GABA and glutamate neurons with glutamine, which is a precursor for both neurotransmitters
- Absorbing glutamate and GABA from the synapse; both roles are accomplished via the GABA-glutamine or glutamine-glutamine cycle
Glutamate: key roles in the brain
Plays key roles in fast excitatory signaling, sleep/wake and learning
GABA: key roles in the brain
Inhibitory signals, motor control, vision and anxiety
Histamine: key roles in the brain
Sleep, circadian rhythms
Histamine: key roles outside of the brain
WBCs, involved in immune responses, itching/allergies
Dopamine: key roles in the brain
Movement, motivation, reward/addiction, hormones
Dopamine: key roles outside of the brain
chemical messenger in kidney, GI tract, pancreas, blood vessels
Serotonin: key roles in the brain
Mood, appetite, sexuality, sleep
Serotonin: key roles outside of the brain
GI tract (intestinal motility), platelets, vasoconstrictor
Norepinephrine: key roles in the brain
alertness, memory, attention
Norepinephrine: key roles outside of the brain
Adrenal glands, fight or flight response
Neurotransmitters only bind to and activate 2 types of receptors:
ionotropic receptors and G-protein couple receptors (GPCRs)
Glutamate receptors
NMDA: Excitatory
AMPA, kainate: Excitatory
mGluR (1-8): Most are excitatory
GABA receptors
GABAa: inhibitory
GABAb: inhibitory
Serotonin receptors
5-HT 1,5: inhibitory
5-HT 3: excitatory
5-HT 2, 4, 6, 7: excitatory
Histamine receptors
H1, H2: Excitatory
H3: Inhibitory
Dopamine receptors
D1, D5: excitatory
D2, D3, D4: inhibitory
Norepinephrine receptors
alpha1, beta1: excitatory
alpha2, beta2, beta3: inhibitory
Acetylcholine receptors
Muscarinic (M1): excitatory
Mescarinic (M2): inhibitory
Nicotinic (N): excitatory
Opiod peptides receptors
all inhibitory
Activated G-proteins can produce effects via either of 2 categories
- G-protein gated ion channels
- G-protein activated enzymes (activate a cascade of downstream signaling molecules)
G-protein gated ion channels
effectors that produce a faster, transcient, more localized effect which can be excitatory or inhibitory, depending on the ion channel (triggers EPSP or IPSP)
G-protein activated enzymes
effectors that produce a slower, more permanent and more widespread effect, and usually cause more complex changes that simple generation of an EPSP or IPSP
Ionotropic receptors
Nicotinic, 5-HT3, AMPA, kainate, NMDA
