Neurotransmitters and its
mechanism of action
Presented by
R.Parthasarathy
INTRODUCTION:
What is neurotransmitter
Criteria
General characteristics features
Classification
biochemical
physiological
Mechanism of action of individual chemical
ANATOMY OF NERVE:
Postsynaptic:
Muscle  Contraction
Neuron  Action potential
Glands  Secretion
DEFINITION:
Neurotransmitters are the
chemical substances
which are responsible for
transmission
of an impulse through a
synapse.
Schematic diagram of synapse
CRETIA:
50 substance are there
 Synthesized by pre-synaptic neurons with the help
of synthesizing enzyme and stored in vesicles at
axon terminal.
 Stimulation of nerve cause release of transmitters.
 Travels between pre to post-synpatic membrane.
 Associated with an enzyme system(inactivation).
 Mimic the effects of nerve stimulation
outside.
 Drugs which modifies nerve stimulation also
modifies transmitter action the similar way.
Neuromediators or neurohormones:
Neuromodulators:
Neuromodulators:
Eg: VIP,somatostatin,ckk,substance P etc
ACTION OF NEUROTRANSMITTERS
general characteristics
Neurotransmitter travels pre  post synaptic
Receptors associated with Ion channels and
enzyme(second messenger)
Acts in milliseconds
Activate both pre and post synaptic receptors.
More transmitter interact both pre and post
synaptically (Sp Rec & sp effects)
CLASSIFICATION:
BIOCHEMICALLY
PYSIOLOGICALLY
EXCITATORY
Eg:Acetylcholine
Aspartate
Dopamine
Histamine
Norepinephrine
Epinephrine
Glutamate
Serotonin
INHIBITORY
GABA
Glycine
Excitatory neurotransmitters:
Inhibitory neurotransmitters:
Acetycholine:
SYNTHESIS:
•
•
•
•
Vasodilation,
cardiac inhibition,
GI peristalsis;
control of thought, mood, sleep, muscles, bladder,
sweat glands
SYNTESIS
Catecholamines:
Dopamine:
Control of movements(parkinsonism)
Induction of vomiting
Inhibition of prolactin secretion
Stimulation of GnRH
Schizophrenia
Serotonin:
SYNTHESIS:
FUNCTIONS:
Regulation
Carbohydrate intake &
Hypthalamic releasing hormone
Pain inhibition
Hallucinations and 5HT
Depression of mood
Histamine:
SYNTHESIS:
Amino acid:
SYNTHESIS:
OVERVIEW
.
Neuropeptide transmitters:
General mechanism of action
Acetylcholine esterase
Thank you