MSc Medical Biochemistry,
norepinephrine , epinephrine
dopamine , serotonin .
gamma amino butyric acid (GABA) ,
glycine , glutamate , aspartate.
carbonmonoxide ( co )
eg : - substance p , neurotensin , enkephalin , β – endorphin , histamine,
vasoactive intestinal polypeptide,
cholecystokinin , neuropeptide Y
2) metabotropic receptors ( interact with G proteins stimulating production of second messengers & activating protein kinases , which modulate the cellular events. )
This contributes to the potential for selective & finely modulated signaling by neurotransmitters
1)voltage gated ion channels
2) neurotransmitter activated ion channels.
4)second messenger system.
Voltage gated potassium channels contribute to repolarization ,this regulate repeated firing of action potential by prolonging after spike repolarization.
choline acetyl transferase
acetyl coA+ choline Ach + coA
nicotinic receptor (nicotine is an agonist for the receptor)
a membrane glycoprotein containing 5 subunits. ( 2αβγδ subunits).
only α subunit binds Ach with high affinity.
2 molecules of Ach binds receptor to open the ion channel which permits Na+ , K+ the receptor is thus transmitter gated ion channel.
autoantibodies to receptors are implicated in causation of myasthenia gravis
Formation of autoantibodies to Ach receptors in NMJ
damage to receptors by autoantibodies
reduction in number of receptors
Episodic weekness of muscles supplied by cranial nerves
acetyl choline esterase
Ach + H2O Acetate +choline
GABA from glutamate in nerve terminal .
1 ) site for transmitter binding glutamate
2 ) a regulatory site that binds glycine.
3 ) a voltage dependent Mg++ binding site
4 ) a site that binds phencyclidine
5 ) a site that binds Zn++.
1) increased intracellular Na+ activates Na+ - Ca++ transporters.]
2)voltage gated Ca++ channels are activated by depolarozation.
3) ITP release Ca++ into cytosol from within endoplasmic reticulum.
Degradation of phospholipids
formation of platelet activating factor (PAF) & release of arachidonic acid
damage by oxygen free radicals
This is called glutamate cascade.
D 1 receptor family(D1 & D5)
D 2 receptor family(D2, D3, D4)
subthalamic nucleus .
( miners) leads to parkinson disease.
dopamine β hydroxylase
dopamine β hydroxylase is bound to inner membrane of synaptic vesicle & release norepinephrine in a tetrameric glycoprotein form.
2) relaxation of gastrointestinal smooth muscle,
3) salivary secretion ,
1) inhibition of transmitter release, (including NE & Ach from autonomic nerves)
2) platelet aggregation
3) contraction of vascular smooth muscle.
4) inhibition of insulin release.
1) increased cardiac rate & force
3) relaxation of visceral smooth muscle,
4) hepatic glycogenolysis,
5) muscle tremor.
1)hallucination & behavioural changes,
2)sleep, wakefulness & mood ,
3) feeding behaviour,
4)control of sensory pathway including nociception,
THANK YOU receptors as fast excitatory transmitter , via metabotropic receptors acts as neuro modulator.