How pain is controlled at brain level ?

1. Pain control at brain
level

2. Content
– Our analegsic system
– Opioids :
a. Endrophin
b. Enkaphlin
– Receptors
– Mechanism
– Areas concerned

3. • pain has 2 components : perception &
reaction
• The degree to which a person reacts to
pain varies tremendously.
• This results partly from a capability of
the brain itself to suppress input of pain
signals to the nervous system by
activating a pain control system called
analgesia system

7. 1.Opioids are the main analgesic system in
brain
2.They are of 2 types: endorphins & enkephlins
3.Drugs that mimic their effect are called opiates
4. Although the opioids have a broad range of
effects, their primary use is to relieve intense
pain, whether that pain is from surgery or a
result of injury or disease such as cancer

8. • Drugs that mimic action of opioids.

9. • The general term endorphins refers to some
endogenous morphine-like substances
whose activity has been defined by their
ability to bind to opiate receptors in the
brain.
• Endorphins(brain polypeptides with actions
like opiates) may function as synaptic
transmitters or modulators. Endorphins
appear to modulate the transmission of pain
signals within sensory pathways.
• When injected into animals, endorphins can
be analgesic

10. • Two closely related polypeptides (pentapeptides)
found in the brain that also bind to opiate receptors
are
• Methionine enkephalin (met-enkephalin) and
leucine enkephalin (leuenkephalin).
• The amino acid sequence of met-enkephalin has
been found in alpha-endorphin and beta-endorphin,
and that of beta-endorphin has been found in betalipotropin, a polypeptide secreted by the anterior
pituitary gland

12. • The major effects of the opioids are
mediated by three major receptor
families.
• These are designated by the Greek
letters μ (mu), κ (kappa), and δ
(delta).
• Each receptor family exhibits a
different specificity for the drug(s) it
binds.

14. Receptors
• The analgesic properties of the opioids
are primarily mediated by theμ
receptors
• .The enkephalins interact more
selectively with the δ receptors in the
periphery
• All three opioid receptors are
members of the G protein–coupled
receptor family and inhibit adenylyl
cyclase

15. • block neurotransmitter release by
A. inhibiting Ca2+ influx into the
presynaptic terminal,
B . open potassium channels, which
hyperpolarizes neurons and inhibits
spike activity.
They act on various receptors in the
brain and spinal cord..

16. • So, activation of the analgesia system
by nervous signals entering the
periaqueductal gray and
periventricular areas, or inactivation
of pain pathways by morphine-like
drugs, can almost totally suppress
many pain signals entering through
the peripheral nerves.

17. • PGA area: enkephalin
• Raphe magnus nucleus :serotonin
• Periventricular nuclei in hypothalamus

19. • Referneces
Guyton textbook of physiology
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