(-)-Epigallocatechin, Antioxidant activity

Supplementary information

This supplementary information is collated from multiple sources and compiled automatically.

The Delta Opioid Receptor Kappa Opioid Receptor and Mu Opioid Receptor also known as DOR KOR and MOR are part of the opioid receptor family. These receptors are G-protein coupled receptors (GPCRs) that respond to endogenous opioids like endorphins and enkephalins as well as synthetic opioids. Each receptor type has a mass of approximately 40 kDa. Opioid receptors are mainly expressed in the central and peripheral nervous systems where they modulate pain perception mood and stress. Distinctions arise in their distribution: Delta and Mu receptors are common in the brain whereas Kappa receptors can be found in larger numbers in the spinal cord.

Biological function summary

Opioid receptors are integral to the modulation of pain and reward systems. They exist as monomers or dimers and can form higher-order complexes with each other or with other GPCRs to influence signal transduction pathways. When activated by their ligands they inhibit cyclic adenosine monophosphate (cAMP) production which reduces neuronal excitability. By interacting with ligand molecules like herkinorin dermorphin and Mu agonists these receptors contribute to the analgesic and euphoric effects typical of opioid ligands.

Pathways

Delta Kappa and Mu receptors play key roles in the endogenous opioid signaling pathways and the dopaminergic reward pathway. These pathways influence neurotransmitter release and neuronal activity often associated with the sensation of pain relief and reward. The dopaminergic pathway also involves proteins like the dopamine transporter protein which works alongside these opioid receptors to regulate dopamine levels in synaptic clefts. Opioid antagonists like naloxone interact with these pathways by blocking the opioid receptors to reverse opioid-induced effects.

The dysregulation of Delta Kappa and Mu opioid receptors associates with chronic pain and addiction. Mu opioid receptors in particular are linked to the development of opioid use disorder due to their involvement in reward processing. Delta receptors have been associated with mood disorders influencing symptoms through their complex interactions with other nervous system proteins. Researchers use compounds like naloxone hydrochloride an opioid antagonist to mitigate conditions related to these receptors. It serves not just as a therapeutic agent but also as a research tool to understand the roles of these receptors in disease contexts.