BIOGENIC AMINES - PowerPoint Presentation

Slide1

BIOGENIC AMINES

DR AMINA TARIQ

BIOCHEMISTRYSlide2

CATECHOLAMINES

Dopamine

Norepinephrine

Epinephrine

These

are biogenic amines and are called

catecholamines

.

Dopamine and

Norepinephrine

function as neurotransmitters in the brain and autonomic nervous system.Slide3

Norepinephrine

and Epinephrine are also synthesized in the adrenal medulla.Slide4

Synthesized from amino acid tyrosine.

Dopa

(3,4

dihydroxyphenyl

alanine

)

Enzyme – Tyrosine hydroxylase Coenzyme – TetrahydrobiopterinAbundant in CNS, Adrenal medulla, sympathetic ganglia.Slide5

Rate limiting step.

Step occurs in mitochondria. Slide6

Dopa

Dopamine + CO

2

Enzyme –

Dopa

decarboxylaseCoenzyme – pyridoxal PO4Slide7

Dopamine is also a neurotransmitter.

Step occurs in the cytoplasm.Slide8

Dopamine

Norepinephrine

Enzyme – Dopamine

hydroxylase

Copper containing enzyme

Dopamine enters the storage granules of

chromaffin cells.Slide9

Norepinephrine

Epinephrine

Enzyme- N-methyl

transferase

Methyl group donor is S-

adenosyl

methionine.CytoplasmSlide10

Source

Almost all adrenaline and half of dopamine comes from adrenal medulla.

Most of the

noradrenaline

and the remaining dopamine diffuse into the

blood stream

from nerve endings, released

as neurotransmitters.Slide11

FATE

The

catecholamines

are degraded by enzymes called:

Monoamine

oxidases

Catechol

-O-methyl transferases.Slide12

Epinephrine (

norepi

)

COMT

Metanephrine

(

normeta) MAO Vanillylmandelic acidSlide13

Epin

/

Norepin

MAO

Dihydroxy mandellic acid COMT Vanillylmandelic

acid

Slide14

MAO INHIBITORS

Prevent the degradation of NE, dopamine and serotonin.

Their levels in the pre synaptic vesicles increase, they leak out in the synaptic space.

And activate their receptors.

This is responsible for the anti depressant effect of MAO inhibitors.(

Tricyclics

and selective

serotinin reuptake inhibitors).Slide15

DOPAMINE

DOPAMINE

is our main focus neurotransmitter.  When dopamine is either elevated or low – we can have focus issues such as not remembering where we put our keys, forgetting what a paragraph said when we just finished reading it or simply daydreaming and not being able to stay on task. 

Dopamine is also responsible for our drive or desire to get things done – or motivation.  Slide16

Common symptoms with

low dopamine

levels are loss of motor control, addictions, cravings, compulsions, and loss of satisfaction.

When dopamine levels are

elevated

symptoms may manifest in the form of anxiety or hyperactivity.Slide17

Drugs like cocaine, opium, heroin, and alcohol increase the levels of dopamine, as does nicotine.

The severe mental illness

schizophrenia

has been shown to involve

excessive amounts of dopamine

in the

frontal lobes

, and drugs that block dopamine are used to help schizophrenics.  On the other hand, too little dopamine in the motor areas of the brain are responsible for

Parkinson's disease,

which involves uncontrollable muscle tremors. 

  Slide18

Dopamine

is a derivative of the

amino acid

tyrosine

. Dopamine is produced by neurons located in a part of the brain called the

Substantia

Nigra (Black Substance), which is part of the Basal Ganglia (a group of structures in the midbrain).Slide19

Dopamine is also a

neurohormone

released by the hypothalamus. Its main function as a

hormone

is to inhibit the release of

Prolactin

from the anterior lobe of the Pituitary.

 Slide20

Dopamine is a

sympathomimetic

catecholamine which exhibits alpha adrenergic, beta adrenergic, and

dopaminergic

agonism

.Slide21

Dopamine can have either an excitatory or inhibitory effect on the postsynaptic potential. When dopamine leaves the

presynaptic

neuron and goes into the synapse, it can then bind to receptors on the postsynaptic neuron.Slide22

After dopamine is bound to the postsynaptic cell, it can either facilitate an action potential or inhibit it. A neuron that classically releases dopamine is called a

dopaminergic

neuron.Slide23

FUNCTIONS

Dopamine plays a significant role in the cardiovascular, renal, hormonal, and central nervous systems.

1. Dopamine is useful in the management of states of low cardiac output, associated with compromised renal function as with

cardiogenic

and

hypovolemic

shock.Slide24

2. Dopamine also causes the release of

norepinephrine

from nerve terminals, which contributes to its effects on the heart.Slide25

3. Dopamine usually increases the systolic and pulse pressure and either has no effect on the diastolic blood pressure or increases it slightly.Slide26

4. Dopamine produces positive

chronotropic

and

inotropic

effects on the myocardium, resulting in increased heart rate and cardiac contractility.Slide27

NOREPINEPHRINE

NOREPINEPHRINE

is an excitatory neurotransmitter that is responsible for stimulatory processes in the body. 

Norepinephrine

helps to make epinephrine as well.  This neurotransmitter can cause ANXIETY at elevated excretion levels as well as some “MOOD DAMPENING” effects. Slide28

Low levels of

norepinephrine

are associated with:

Low Energy,

Decreased Focus ability and

Sleep cycle problems.Slide29

EPINEPHRINE

EPINEPHRINE

is an excitatory neurotransmitter that is reflective of stress. 

This neurotransmitter will often be

elevated

when ADHD like symptoms are present. 

Long term STRESS or INSOMNIA can cause epinephrine levels to be

depleted.  Epinephrine also regulates HEART RATE and BLOOD PRESSURE.Slide30

Low

levels of epinephrine contribute to fatigue, weight gain and poor concentration.

Elevated

levels of epinephrine can be factors contributing to restlessness, anxiety, sleep problems, or acute stress.Slide31

FUNCTIONS

Regulators of carbohydrate and lipid metabolism.

Increase the degradation of glycogen and TG.

Increase blood pressure and output of heart.Slide32

Learning Resources

Lecture Notes

Lippincott biochemistry