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dextromethorphan overdose p. 711
heroin detoxification p. 600
for opioid toxicity p. 249, 572, 594
To understand how opioids work, let’s zoom into a region of the brain tissue that has opioid receptors.
Normally, in the absence of endorphins, inhibitory neurons secrete a neurotransmitter called gamma-aminobutyric acid, or GABA, that prevents nearby neurons from releasing neurotransmitters like dopamine, serotonin, and norepinephrine.
Now, let’s say someone goes to play a rigorous game of badminton. Exercise releases endorphins which activate the three major opioid receptors located on the inhibitory neurons, called the mu, kappa, and delta receptors.
As endorphins bind to these receptors, they block the inhibitory neuron from releasing GABA, allowing the dopamine, serotonin, and norepinephrine secreting neurons to freely unload their neurotransmitters, which then gets picked up by another neuron in the same area.
Opioid antagonists are drugs that strongly bind to opioid receptors and prevent their activation. They are used to treat opioid overdose and addiction, and can also help to reverse respiratory depression and other adverse effects of opioids. Examples include drugs like naloxone, naltrexone, methylnaltrexone, and alvimopan.
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