In this talk we will discuss the following topics:
Opioid receptor structure.
Second messenger system overview.
Desensitization: an immediate effect of opioid use on the receptors and the second messenger system.
Tolerance: days to a week after opioid use disorder the mechanism for sensitization to kick in.
Dependence: a need for opioid use due to severe pains leading to dependence. (See DSM-4 for an exhaustive diagnostic criteria)
Addiction and withdrawal: an addictive state. (See DSM-4 and DSM-5 for an exhaustive diagnostic criteria.)
Opioid receptor disposition.
Adaptation of intracellular signaling mechanism.
System level counteradaptation.
Differential tolerance development.

References:

Effects of Acute and Chronic Opiate Receptor Activation
Brunton, Laurence; Knollman, Bjorn; Hilal-Dandan, Randa. Goodman and Gilman's The Pharmacological Basis of Therapeutics, 13th Edition (Goodman and Gilman's the Pharmacological Basis of Therapeutics) (p. 1362). McGraw Hill LLC. Kindle Edition.

Receptor specificity of endogenous opioids and effects of receptor activation on neurons.
Brunton, Laurence; Knollman, Bjorn; Hilal-Dandan, Randa. Goodman and Gilman's The Pharmacological Basis of Therapeutics, 13th Edition (Goodman and Gilman's the Pharmacological Basis of Therapeutics) (p. 1358). McGraw Hill LLC. Kindle Edition.


FDA's recommendations for OUD:
Information about Medication-Assisted Treatment (MAT) | FDA
https://www.fda.gov/drugs/information-drug-class/information-about-medication-assisted-treatment-mat

Diagnostic criteria for opioid use dependence and opioid use disorder
The ASAM National Practice Guideline for the Treatment of Opioid Use Disorder – 2020 Focused Update
https://www.asam.org/quality-care/clinical-guidelines/national-practice-guideline?gclid=CjwKCAiAg9urBhB_EiwAgw88mZm1lh6sE-rLtgkJP3w3ij1KSUJ4PkKqNrISFpagDzlQbRitsIJFBhoCQJIQAvD_BwE

npg-jam-supplement.pdf
https://sitefinitystorage.blob.core.windows.net/sitefinity-production-blobs/docs/default-source/guidelines/npg-jam-supplement.pdf?sfvrsn=a00a52c2_2

Psychiatry Online | DSM Legacy
https://dsm.psychiatryonline.org/dsmPreviousEditions

APA_DSM_Changes_from_DSM-IV-TR_-to_DSM-5.pdf
https://www.psychiatry.org/File%20Library/Psychiatrists/Practice/DSM/APA_DSM_Changes_from_DSM-IV-TR_-to_DSM-5.pdf