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opium
extract of poppy plant
source of the opiate/opioid family
opiate
substance derived from the opium poppy
opioid
includes opiates, synthetic substances, and endogenous peptides that bind to opioid receptors
narcotic analgesics
reduce pain without producing unconsciousness
can produce euphoria, relaxation, and sleep
high doses can lead to coma/death (respiratory failure)
how can opioid drugs be used? (besides pain)
life saving treatment for diarrhea in cases of severe bacterial and parasitic disease
constipation is common side effect of opioid use
morphine
active ingredient in opium
contains codeine, thebaine, narcotize
,what can morphine modifications do?
some modifications of morphine produce partial agonists which have less analgesic effects
which decreases the risk of dependence
neutral antagonist (opioids)
naloxone, nalorphine (entirely synthetic)
can prevent or reverse the effects of opioid overdose
K opioid receptors
found in striatum, amygdala, hypothalamus, and pituitary
associated with regulation of pain perception, gut motility, dysphoria, and homeostasis
NOP-R receptor (nociception/orphaning EQ receptor)
opioids don't bind to NOP-R and it doesn't bind to classical opioid receptors
widely distributed in the PNS and CNS
role in analgesia, feeding, motor function, learning, and neuroendocrine regulation
4 opioid receptors
are similar to proteins linked to g proteins
metabotropic
, mu opioid receptor
high affinity for morphine and other opioids
found in medial thalamus, periaqueductal gray, median raphe, spinal cord (morphine induced
analgesia)
nucleus accumbent (role in feeding and positive reinforcement)
delta opioid receptor
found in neocortex, striatum, olfactory areas, substantial nigra, and nucleus accumbent
role in olfaction, motor integration, reinforcement, and cognitive functioning
properties
endogenous opioids are formed from larger precursor peptides manufactured in the soma
cut by enzymes into smaller molecules, stored in vesicles, and transported down the axon
endorphins that stimulate mu and delta receptors
cleaved from POMC (concentrated in the pituitary gland)
enkephalins that stimulate delta receptors
cleaved from proenkephalin
dynorphins that stimulate k receptors
cleaved from prodynorphin
endorphins