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Any of various compounds that bind to specific receptors in the central nervous system and have analgesic and narcotic effects, including naturally occurring substances such as morphine; synthetic and semisynthetic drugs such as methadone and oxycodone; and certain peptides produced by the body, such as endorphins. Also called opiate.

o′pi·oid′ adj.


a. any of a group of substances that resemble morphine in their physiological or pharmacological effects, esp in their pain-relieving properties
b. (modifier) of or relating to such substances: opioid receptor; opioid analgesic.


(ˈoʊ piˌɔɪd)

1. any opiumlike substance, as the endorphins produced by the body or the synthetic compound methadone.
2. pertaining to such a substance.


adj & n opioide m
References in periodicals archive ?
Evidence that intermittent, excessive sugar intake causes endogenous opioid dependence.
Similarly, activating the endogenous opioid system after exercise in the present study has demonstrated a reduced desire of using morphine (Figure 2).
Researchers have explored the involvement of the endogenous opioid system in the antinociceptive effect of medicinal herbs (Calixto et al.
Central endogenous opioid inhibition of supraoptic oxytocin neurons in pregnant rats.
Researchers hypothesize either the number of MOP receptors is reduced or the endogenous opioid production pathways are altered; either way, the body becomes less capable of modulating pain impulses (Briggs, 2010; Rodriguez 2015).
The endogenous opioid system is involved in a variety of physiological processes such as analgesia, stress, reward or adaptive homeostatic functions (temperature control, water and food intake).
In particular, nicotine enhances the endorphinic mu receptor mRNA and protein expression in brain regions important for drug reward in rodents [4,5] and stimulates endogenous opioid release [6], resulting in mu receptor activation.
One limitation of our study is that it did not directly measure endogenous opioid levels in the participants.
14] When a subject anticipates that pain will be relieved, the endogenous opioid system is activated, causing a powerful analgesic effect.
Opioid drugs are agonists that bind to endogenous opioid receptors and mimic the actions of natural morphine-like ligands.
The long-lasting nature of the phenomenon suggests that endogenous opioid analgesia silently continues long after an injury has healed.
These areas partake in the modulation of chronic pain in a fashion similar to the endogenous opioid system (Hohmann & Suplita 2006; Mackie 2010).