Opioid Receptors
Opioid receptors are integral components of the endogenous opioid
system, which regulates pain perception and various physiological
functions. Receptors mu (MOR), delta (DOR), and kappa (KOR) mediate the
effects of endorphins, enkephalins, and dynorphins, which are endogenous
opioid peptides (S. S. Shenoy & Lui, 2023). While known for their role
in pain modulation, opioid receptors have also been implicated in the
regulation of immune responses and cancer progression (Boland &
Pockley, 2018). The interaction between opioid receptors and the immune
system is complex, with evidence suggesting both immunosuppressive and
stimulatory effects. The immunosuppressive potential of opioids,
particularly through MOR activation, has raised interests in blocking
the receptor to revive anti-tumor immune responses (Gondoh et
al. , 2022; Lennon, Moss, Singleton, & Riou, 2012).