Δ-opioid
n/a
The δ-opioid receptor, also known as delta opioid receptor or simply delta receptor, abbreviated DOR, is a 7-transmembrane G-protein coupled receptor, that has enkephalins as its endogenous ligands. The regions of the brain where the δ-opioid receptor is largely expressed vary from species model to species model. In humans, the δ-opioid receptor is most heavily expressed in the basal ganglia and neocortical regions of the brain; the basal ganglia, which is heavily GABA populated, has been linked to major depressive disorder, suggesting a possible role for the δ-opioid receptor in mood modulation.
The endogenous system of opioid receptors (μ MOR,κ KOR, and, δ DOR) is well known for its analgesic potential; however, the exact role of δ-opioid receptor activation in pain modulation is largely up for debate. Largely this also depends on the model at hand since receptor activity is known to change from species to species. Activation of δ receptors produces analgesia, perhaps as significant potentiators of mu-opioid agonists. However, it seems like delta agonism provides heavy potentiation to any MOR agonism. Therefore, even selective mu agonists can cause analgesia under the right conditions, whereas others can cause none whatsoever. It is also suggested however that the pain modulated by the mu-opioid receptor and that modulated by the δ-opioid receptor are distinct types, with the assertion that DOR modulates the nociception of chronic pain, while MOR modulates acute pain.
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