Recceptors Flashcards
GPCR’s
G-protein coupled receptors
Gs and Gq are excitatory recepetors
Gi is an inhibitatory receptor
Ionotropic
Ligand gated ion channels
Multi-subunit and heterogenous
Rapid cellular effects
Affects pharmacology and pharmacology
Metabotropic
GPCR's Can be homo/heterodimers Slower and more diffuse response involved in neromodulation Can activate 2nd messenger systems Can also act as auto-receptors
Autoreceptors
A form of negative feedback where the neurotransmitter the receptor released can bind to that receptor and deactivate it preventing synaptic levels of that neurotransmitter getting too high.
GABAa receptors
Iontropic: Cl- channel
Fast acting and inhibitory
Can be targeted by agonist muscimole and antagonist biculline
GABA binds to orthosteric site
GABAb receptors
Metabotropic: heterodimer
Made up of R1 which has a venus fly trap GABA binding site while R2 traffics the receptor up to the surface
Closes Ca2+ channels presynaptically to reduce neurotransmitter release
Open K+ channels postsynaptically resulting in a slow hyperpolarisation
Targeted by GABAb agonist Baclofen
GABAc receptors
Ionotropic: Cl- channel
Fast inhibitory action
Targeted by agonist GABA/muscimol and antagonist TPMPA
NMDA recepetors
Ionotropic: Voltage gated Ca2+ ion channel
Usually blocked by Mg2+ but this block disappears when the cell is depolarised
Activation requires both glutamate and glycine
Antagonised by Ketamine/phenylcyclidine
Increases Glu release presynaptically via increasing Ca2+ influx
mGlu receptors
Metabotropic
Slow neuromodulatory role
Gp1 receptors found presynaptically, Gp2/3 are found post synaptically
Reduces glutamate release presynaptically by decreasing Ca2+ influx
VMAT
Vesicular mono amine transporter
Only present on vesicle membranes
Transports monoamines into vesicles for storage
COMT
Catechol O methyl transferase
Inactivates NA/DA
Overexpression of COMT is a phenotype for schizophrenia
MAO
Monoamine oxidase
Inactivates NA/DA/5HT
DAT
Dopamine transporter
Present on cell surface membrane for uptake of DA from synaptic cleft
NAT
Noradrenaline transporter
Present on cell surface membrane for uptake of NA from synaptic cleft
SERT
Serotonin transporter
Present on cell surface membrane for uptake of 5HT from synaptic cleft
5HT receptors
5HT1-7
5HT3 is ionotropic, rest are metabotropic
NA receptors
Alpha 1/2 and Beta 1/2
DA recepetors
D1-Gs coupled
D2-Gi-coupled
All are metabotropic
ACh receptors
ACh acts on nicotinic (ionotropic) and muscarinic (metabotropic) receptors
AChesterase
Acetylcholinesterase is the enzyme that inactivates ACh in the synpatic cleft to free choline and acetyl groups
Histamine receptors
H1-4 are all GPCR’s
H1 receptors on C-fibres sensitise VR-1 nociceptors and respomds to histamine released by mast cells
ASIC receptor
Acid sensing ion channel
Nociceptive receptor
Allows influx of Na+
Detects H+ ions at free nerve endings
Purinergic receptors
Nociceptive receptor that detects ATP and high threshold mechanical stimulation (really hard hits)
Allows influx of Na+
Can also detect the ATP released by damaged cells
Voltage gated Na+ channel (VGNa) (C-fibre associated)
Detects mechanical stimuli
Allows influx of Na+
VR-1/TRPV-1/Vanilloid/Capsacin recepetor
Responds to H+ ions and heat
Also activated by capsacin
Opens to allow entry of Na+/Ca2+ and form graded potentials
TrKA receptor
Responds to NGA (nerve growth factor)
Involved in nociceptor sensitisation via sensitising VGNa and VR-1 receptors
Prostanoid receptors
Responds to prostaglandins
Involved in nociceptor sensitisation via sensitising BK1 and VGNa receptors
BK2 receptors
Bradykinin receptor
Involved in nociceptor sensitisation via sensitising VR-1 receptors
Mu opioid receptor
The only opioid receptor in the brain but also found along spine and periphery
Involved in analgesia, euphoria, respiratory depression and constipation
Delta opioid receptor
Only found along the spine
Involved in analgesia, dysphoria and diuresis
Kappa opioid receptor
Found along the spine and periphery
Invloved in analgesia and acts as a proconvulsant
Features found in all opioid receptors
Gi coupled receptor
Opens Ca2+/Closes K+
Decreases conversion of AMP to cAMP therefore there is less PKA
