Small molecules transmitters PDF

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Summary

table of neurotransmitter and small molecular transmitters...

Description

Small molecules transmitters acetylcholine

effect Mostly excitatory, sometimes inhibitory

Origin   

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Norepinephrine

Mostly excitatory, sometimes inhibitory

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Site of action Large pyramidal cells Neurons of basal ganglia Preganglionic fibers of autonomic nervous system Post-ganglionic fiber of parasympathetic and sympathetic nervous system Cells bodies in brain stem and hypothalamus Nucleus locus ceruleus of pons Post-ganglionic nerve fibers of sympathetic nervous system Neurons of Substancia niagra

Dopamine (low in Parkinson’s disease) Glycine

Inhibitory



Inhibitory



Synapse of spinal cord

GABA (gammaaminobutyric acid)

Inhibition

Glutamate

Excitation

    

Serotonin

Inhibitor

 

Basal ganglia Spinal cord Cerebellum Cortex Pre-synaptic terminals of sensory pathway Cerebral cortex Nuclei of median raphe of brain stem

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Widespread areas of the brain

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Striatal region of basal ganglia

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Spinal cord Brain stem Hippocampus Synapse of spinal cord

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Neuronal cells Gilial cells

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Inhibitory pathways of spinal cord Higher regions of the nervous system

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Nitric oxide

Inhibitory

 

Cortex Endothelial cells

Periphery parasympathetic nerve endings Vagus nerve

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Small molecule neurotransmitter Rapid acting Synthesized in cytosol of soma

Absorbed into vesicles by active transport and stored Effect is to cause increase or decrease in conductance

Vesicles containing small transmitters are continually recycled Example:  Ach synthesized in the pre-synaptic terminal membrane Acetyl Coenzyme A + Choline → Ach (choline acetyl transferase  Ach recycled in the synaptic cleft Ach → Acetate + choline (cholinesterase

Nitric oxide Rapid acting small transmitter Synthesized at the presynatic membrane terminal as and when needed

Is not stored in vesicles and released instantly after synthesis Has inhibitory effect on nervous system Does not alter the membrane potential but changes intracellular metabolic function

Neuropeptides

Synthesized as integral part of large proteins by ribosomes and neuronal cell body → endoplasmic reticulum → golgi apparatus 1. Neuropeptides broken into smaller fragments 2. Packaged into vesicles Vesicle then moves to Vesicle is autolyzed and not reused Effect if more prolonged, as they are highly potent...