Opioid Modulation of the Gut-Brain Axis in Opioid-Associated Comorbidities.

Growing evidence from animal and human studies show that opioids have a major impact on the composition and function of gut microbiota. This leads to disruption in gut permeability and altered microbial metabolites, driving both systemic and neuroinflammation, which in turn impacts central nervous system (CNS) homeostasis. Tolerance and dependence are the major comorbidities associated with prolonged opioid use. Inflammatory mediators and signaling pathways have been implicated in both opioid tolerance and dependence. We provide evidence that targeting the gut microbiome during opioid use through prebiotics, probiotics, antibiotics, and fecal microbial transplantation holds the greatest promise for novel treatments for opioid abuse. Basic research and clinical trials are required to examine what is more efficacious to yield new insights into the role of the gut-brain axis in opioid abuse.