Allostatic Mechanisms of Opioid Tolerance Beyond Desensitization and Downregulation.
Level 5 - mechanism / opinion, no new human data
Narrative review and mechanistic framework without systematic search or primary human clinical data
PubMed 27670390 · doi:10.1016/j.tips.2016.08.002
What was done
This narrative review describes mechanisms of opioid tolerance extending beyond direct opioid receptor signalosome desensitization and downregulation. It outlines conceptual models of cellular allostasis, downstream circuit adaptation (termed pass-forward allostasis), agonist bias, differences between μ- and δ-opioid receptor signaling, and neuron-microglia interactions in tolerance development.
What was found
The abstract reports no quantitative measurements or numerical data. It provides a theoretical synthesis proposing that direct cellular adaptations to opioids propagate through interconnected brain circuitry and neuroimmune signaling to produce both analgesic and hedonic tolerance.
Why it matters
It broadens the framework for understanding opioid tolerance from isolated receptor desensitization to circuit-level neuroadaptations and neuroimmune interactions across the central nervous system.
Limits
This is a narrative review presenting mechanistic theory rather than primary empirical data. No sample sizes, quantitative outcomes, clinical populations, or systematic search methods are reported in the abstract.
Cited by
- contradicts When a drug is introduced to the body, the brain responds by upregulating the receptors for that drug.