PHAR: Introduction to Neurotransmitters Flashcards
What are 6 neurotransmitters that were looked at as example?
- Acetylcholine
- Noradrenaline
- 5-hydroxytryptamine (serotonin)
- Dopamine
- Glutamate
- GABA (γ-aminobutyric acid)
What are the 2 main receptor types of neurotransmitters?
- G-protein-coupled receptors (GPCRs).
- Ligand-gated ion channels.
Is Glutamate excitatory or inhibitory?
Primary EXCITATORY neurotransmitter in the CNS.
Where is glutamate most abundant?
- Cortex.
- Basal ganglia.
- Sensory pathways.
- What are the 4 main glutamate receptor subtypes?
- Which are ligand-gated and which are GPCR?
- 3 ligand-gated Na+/Ca2+ channels:
- NMDA (GluN).
- AMPA (GluA).
- Kainate (GluK).
- 1 G-protein-coupled receptor:
- Metabotropic (mGluR).
Is γ-Aminobutyric Acid (GABA) an inhibitory or excitatory neurotransmitter?
GABA is the primary INHIBITORY neurotransmitter in the CNS.
- What are the 2 main GABA receptor subtypes?
- Ligand-gated or GPCR?
- 1 x Ligand-gated Cl- channel:
- GABAA receptor (Cl- channel opening → hyperpolarisation)
- 1 x G-protein-coupled receptor:
-
GABAB receptor (inhibits activity of adenylyl cyclase).
- Adenylyl cyclase plays a regulatory role for cells (converts ATP to cAMP)
-
GABAB receptor (inhibits activity of adenylyl cyclase).
Which 2 neurotransmitters are amino acids?
- Glutamate.
- GABA.
Is acetylcholine excitatory or inhibitory?
Mostly EXCITATORY neurotransmitter, can be INHIBITORY.
What are the 2 main acetylcholine receptor subtypes?
-
Nicotinic (nACh receptors) - all excitatory
- Ligand-gated Na+/Ca2+ channels.
-
Muscarinic (mACh receptors) - some excitatory, some inhibitory (don’t need to know which)
- G-protein coupled receptors.
What is the role of acetylcholine?
- Widespread in CNS.
- Main peripheral transmitter of parasympathetic system and motor neurons.
Which are the 3 main neurotransmitters from the monoamine group?
- Noradrenaline (norepinepherine).
- Dopamine.
- Serotonin/5-hydroxytrypatmine (5-HT).
Where are NA neurons mainly located?
-
Locus coeruleus. Sends axons to:
- Cortex
- Hippocampus
- Cerebellum
- Spinal cord
Main peripheral transmitter of sympathetic nervous system.
What does the locus coeruleus mediate?
- Arousal.
- Sleep.
- Anxiety.
- Mood.
What do α-adrenoceptors in the medulla regulate?
Blood pressure.
What are the 2 main noradrenaline receptor types?
- G-protein coupled receptors.
- α-adrenoceptors - excitatory.
- β-adrenoceptors - most are inhibitory.
What are the 3 main dopamine pathways in CNS and what do they control?
-
Nigrostriatal.
- Motor control (associated with Parkinson’s disease).
-
Mesolimbic/mesocortical.
- Emotion, reward, arousal (associated with addiction and psychosis).
- Tuberohypophyseal.
- Prolactin secretion (associated pituitary system).
What are the receptors of dopamine?
- G-protein coupled receptors
- D1, D5 - stimulate adenylyl cyclase.
- D2, D3, D4 - inhibit adenylyl cyclase.
What is the common name for 5-hydroxytryptamine (5-HT)?
Serotonin.
Where are 5-hydroxytyptamine neuron bodies mainly located?
Raphe nuclei (pons-medulla), project axons to:
- Cortex.
- Hippocampus.
- Basal ganglia.
- Limbic system.
- Hypothalamus.
What are the 5-hydroxytryptamine receptor subtypes?
- G-protein coupled receptors:
- 5-HT1 - inhibitory
- 5-HT2 - excitatory
- Ligand-gated cation channel:
- 5-HT3 - excitatory
What are the 5-Hydroxytryptamine (serotonin) receptors associated with?
- 5-HT1 - inhibitory - antidepressant, lowering appetite.
- 5-HT2 - excitatory - agitation, hallucinations.
- 5-HT3 - excitatory - nausea.
5-hydroxytryptamine also regulates:
- Nociception.
- Temperature.
- Blood pressure.
What are 3 mechanisms neurotransmitter related drugs are put into therapeutic practice?
- Regulating neurotransmitter abundance (e.g. SSRI antidepressants).
- Activating a receptor (e.g. beta-adreneoceptor agonists in asthma).
- Inhibiting a receptor (e.g. 5HT3 receptor antagonists for nausea).
Describe the process of glutamate being deactivated to glutamine.
- When glutamate has interacted with the receptor may be taken back up, or may be taken up to adjacent astrocytes where it undergoes deactivation by the process glutamate → glutamine.
- Astrocyte ejects it from the cell and can be used for other metabolic purposes.
- Neurone can reverse process to restore glutamate.
Why are Na+/Ca2+ channels excitatory?
- Rush of cations into cell.
- Increase of membrane polarity.
- Brings membrane potential closer to zero.
- Depolarisation occurs → excitatory response.
