Neurotransmitters and its mechanism of action

Presented byR.Parthasarathy

INTRODUCTION:

What is neurotransmitterCriteriaGeneral characteristics featuresClassification biochemical physiologicalMechanism of action of individual chemical

ANATOMY OF NERVE:

Postsynaptic:

Muscle ContractionNeuron Action potentialGlands 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:

Eg: VIP,somatostatin,ckk,substance P etc

Neuromodulators:

ACTION OF NEUROTRANSMITTERS general characteristics

Neurotransmitter travels pre post synapticReceptors associated with Ion channels and

enzyme(second messenger)Acts in millisecondsActivate both pre and post synaptic receptors.More transmitter interact both pre and post

synaptically (Sp Rec & sp effects)

CLASSIFICATION: BIOCHEMICALLY

PYSIOLOGICALLY

EXCITATORYEg:Acetylcholine

Aspartate

Dopamine

Histamine

Norepinephrine

Epinephrine

Glutamate

Serotonin

INHIBITORYGABA

Glycine

Excitatory neurotransmitters:

Inhibitory neurotransmitters:

Acetycholine:

SYNTHESIS:

• Vasodilation, • cardiac inhibition, • GI peristalsis; • control of thought, mood, sleep, muscles, bladder, sweat

glands

Catecholamines:

Dopamine:Control of movements(parkinsonism)Induction of vomitingInhibition of prolactin secretion Stimulation of GnRH Schizophrenia

SYNTESIS

Serotonin:

SYNTHESIS:

FUNCTIONS:Regulation Carbohydrate intake & Hypthalamic releasing hormonePain inhibitionHallucinations and 5HTDepression of mood

Histamine:

SYNTHESIS:

Amino acid:

SYNTHESIS:

OVERVIEW.

Neuropeptide transmitters:

General mechanism of action

Acetylcholine esterase

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