Kappa-type opioid receptor and Delta-type opioid receptor

Kappa opioid receptor and delta opioid receptor are two distinct members of the opioid receptor family, functioning as G protein-coupled receptors predominantly expressed in the nervous system and peripheral tissues. Kappa opioid receptor (KOR) is primarily activated by the endogenous peptide dynorphin and mediates analgesia, diuresis, and dysphoria, while delta opioid receptor (DOR) is activated by enkephalins and is involved in analgesia, modulation of emotional states, and inhibition of gastrointestinal motility. Both receptors have been investigated as alternative therapeutic targets to mu opioid receptors for pain and neuropsychiatric disorders due to their potentially favorable side effect profiles, although each presents unique pharmacologic and safety challenges. Drugs targeting these receptors include both selective agonists and antagonists, and research continues to identify clinical uses that can minimize side effects such as dysphoria (for KOR) or convulsions (for DOR)

Other names

KOROpioid receptor kappa-1OPRK1DOROpioid receptor delta-1OPRD1

Agonists mimic endogenous ligands, activating receptor and Gi/o proteins, inhibiting adenylate cyclase, reducing cAMP, and leading to inhibitory effects at synapses. Antagonists bind to the receptor without activating it, blocking agonist effects. Partial agonists and biased agonists can show selective activation of signaling pathways or tissue selectivity