Helps transfer information in the form of

nerve impulse

Pre-synaptic to postsynaptic

Neurohormones ?

Must be synthesized by a neuron

Stored in pre-synatic endings

Released at the synapse

Has specific receptors on Post-synaptic

membrane

Suitable termination of action

Group Ex’s

Acetylcholine Ach

Catecholamines NE, Epinephrine, Dopamine,

Serotonin, Histamine

Amino Acids Excitatory – Glutamate, Aspartate

Inhibitory – GABA , Glycine

Polypeptides ADH, oxytocin , endorphines ,

enkephalines , somatostatin ,

sunstance p , CRH, TRH..etc

Purines Adenosine , ATP

Gases NO , CO

Distribution

› All preganglionic neurons

› Post-ganglionic parasymapthetic

› Neuromuscular junctions

› Many parts of brain

› Amacrine cells in retina

Nicotinic – ligand gated ion channel

› Two subtypes

Muscarnic – G protein coupled

› Five subtypes (M1 to M5 )

Post ganglionic sympathetic nerves

Adrenal medulla (NE)

Properties Adrenalin & Nor-

Adrenalin

Dopamine

Receptors Alpha – 1, 2

Beta – 1, 2, 3

D1-5

Termination MAO

COMT

Same

Major inhibitory neurotransmitter in brain

and retina

Produced by decarboxylation

glutamate by glutamate decarboxylase

GABA a Brain Ligand gated ion

channel

GABA b Brain G protein coupled

GABA c Retina Ligand gated ion

channel

Inhibitory neurotransmitter

Site of action for

Anaesthetics

Sedatives ( benzodiazepins )

Alcohol

Predominantly inhibitory neurotransmitter

Glutamate

› major excitatory neurotransmitter

› Derived from kreb cycle

› Termination – taken up by astrocytes

› Excitotoxic

Aka 5 – Hydroxy tryptamine

Found in CNS , ENS , retina

In brain Raphe nucleus contain serotonin

Derived from trptophan

Receptors are 5HT 1-7 ( 7 types with subtypes )

Acts as a mood elevator

Hallucinogen

Also secreted by enterochromaffin cells ,platelets , basophills

Smooth muscle contraction ,

Neurotransmitter and hormone

Hypothalamus , limbic system

H1, H2, H3

Smooth muscle contraction

Secretion of HCL

Increased capillary permeability

Its one of the major tachykinin

(polypeptide11AA)

Found in many parts of brain , GIT,

Nerves

NK 1 , 2, 3 are receptors

Neurotransmitter for pain in dorsal horn

of spinal cord

in hypothalamus for endocrinal

modulation

Axon reflex

Peristalsis in gut

Along with dopamine in basal ganglia

Aka endothelium derived relaxing factor

(EDRF)

Blood vessels , brain

Derived from arginine by NO synthase