Astroglia (brain support cells) from multiple brain regions carry both delta and kappa opioid receptors that inhibit cAMP signaling.
Co-localized on same cellBoth delta and kappa opioid receptors found together on individual astroglia across cortex, striatum, and brainstem
What the researchers found
Delta and kappa opioid receptors were co-localized on astroglia from cortex, striatum, and brainstem. Both inhibited adenylate cyclase and modulated beta-receptor-stimulated cAMP.
Why it matters
Brain support cells (astroglia) outnumber neurons. Finding functional opioid receptors on them means the opioid system affects brain function more broadly than just through neurons.
How the study worked
Primary astroglial cultures from neonatal rat cortex, striatum, and brainstem were treated with receptor-selective opioid ligands. cAMP accumulation was measured.
What this study cannot tell us
In vitro cell culture study using neonatal cells. Cultured astroglia may not behave the same as mature cells in the intact brain. Mu receptors were not detected.
How to read the evidence
Preliminary — in vitro study using neonatal rat astroglial cultures. Demonstrates the receptors exist and function but doesn't confirm behavior in mature, intact brain tissue.
When this study was published
Published in 1992 (34 years ago). Glial opioid signaling has since become a recognized field, validating these early findings.
The bigger picture
Astroglia outnumber neurons in the brain and play critical roles in supporting neural function. Discovering that opioids directly affect these cells expands our understanding of how the opioid system influences brain activity far beyond simple pain signaling.
Questions still open
- How do astroglial opioid receptors contribute to opioid drug effects and addiction?
- Could targeting astroglial opioid receptors provide new approaches to pain management with fewer side effects?
Common questions
What are astroglia?
Why does it matter that support cells have opioid receptors?
Read the original research
Delta and kappa opiate receptors in primary astroglial cultures. Part II: Receptor sets in cultures from various brain regions and interactions with beta-receptor activated cyclic AMP.
Neurochemical research, 17(6), 545-51
Citation
Eriksson, P S; Hansson, E; Rönnbäck, L. (1992). Delta and kappa opiate receptors in primary astroglial cultures. Part II: Receptor sets in cultures from various brain regions and interactions with beta-receptor activated cyclic AMP.. Neurochemical research, 17(6), 545-51.