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Pain control at brain level


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How pain is controlled at brain level ?

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Pain control at brain level

  1. 1. Pain control at brain level
  2. 2. Content – Our analegsic system – Opioids : a. Endrophin b. Enkaphlin – Receptors – Mechanism – Areas concerned
  3. 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
  4. 4. 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
  5. 5. • Drugs that mimic action of opioids.
  6. 6. • 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
  7. 7. • 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
  8. 8. • 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.
  9. 9. 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
  10. 10. • 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..
  11. 11. • 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.
  12. 12. • PGA area: enkephalin • Raphe magnus nucleus :serotonin • Periventricular nuclei in hypothalamus
  13. 13. • Referneces Guyton textbook of physiology