Download Neurotransmission in the CNS

Neurotransmission and the CNS
BY
PROF. Azza El-Medany
Neurotransmitters
• Exert their effect by binding to specific
receptors on the neuronal postsynaptic
membranes.
• They can either excite the neurons → increase
their activity or inhibit the neurons →
suppressing their activity.
What is the importance of
understanding neurotransmitters
 To understand the etiology of diseases
To suggest the best drugs to be used
To understand the other clinical uses of any
particular drug
Examples of some neurotransmitters
& their relation to diseases
• Acetylc holine
• Type of receptors :
Muscarinic receptors
Nicotinic receptors
Role of Acetylcholine in the CNS
• Ach is thought to be involved in cognitive
functions such as : memory , arousal and
attention. It plays a role in the enhancement
of sensory perception when we wake up .
• Damage of cholinergic pathways is associated
with memory deficits associated with
Alzheimer,s disease.
Continue
• Treatment of Alzheimer,s disease involved the
use of directly & indirectly acting
cholinomimetic drugs.
• Increase brain level of Ach predispose to
parkinson,s disease.
Mood Disorders and
Neurotransmitters
• Norepinephrine ( NEF ) :
• Increase norepinephrine release tend to
increase excitatory activity within the brain →
Mania
• Treatment :
Drugs that decrease NEF e.g. neuroleptic
drugs
NEF ( continue )
• Decrease of NEF brain level→ Depression
• Treatment :
Drugs that increase NEF e.g. Tricyclic
antidepressant drugs
Serotonin
• Although the CNS contains less than 2% of the
total serotonin in the body, serotonin plays a
very important role in a range of brain
functions including :
• Mood control
• Regulation of sleep
• Pain perception
• Body temperature
Serotonin( continue )
• Blood pressure
• Hormonal activity
Diseases that influenced by serotonin
( 5-HT) level
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Affective Disorders or Bipolar disorders
Schizophrenia
Obsessive Compulsive Disorders
Generalized Anxiety
Depression
Premenstrual dysphoric disorder
Continue
• Outside the brain , serotonin exerts a number
of important effects , involving
gastrointestinal & cardiovascular systems
Dopamine
• Monoamine neurotransmitter, concentrated
in very specific groups of neurons called basal
ganglia.
• Three important pathways throughout the
brain :
• Nigrostriatal
• Mesolimbic
• Tuberoinfundibular
Continue
• ↑ of dopamine levels in brain has a role in the
development of schizophrenia
Treatment by blocking dopamine receptors
by neuroleptic drugs .
• ↓ of dopamine levels is a contributing factor
in parkinson,s disease .
Treatment by increasing dopamine content.
GABA & Glutamate Transmitters
• Decrease in GABA levels ( an inhibitory
neurotransmitters ) or increase in glutamate (
an excitatory neurotransmitters )
• Predispose to epilepsy
Treatment by antiepileptic drugs
Conclusion
• Understanding the numerous
neurotransmitters , their receptors , location
and interaction with one another has been
central to the design of medicines for mental
illness.
• This acquired knowledge has led to the
development of successful products for many
brain disorders including depression, anxiety,
sc hizophrenia, parkinson,s disease & epilepsy.
Continue
• Combinations of centrally acting drugs are
frequently given to therapeutic advantages
e.g. an anticholinergic drug & levodopa in
for parkinson,s disease