Morphine-induced dysbiosis and metabolic remodeling of the gut microbiota is transmissible via fecal microbiota transplantation in mice.

OBJECTIVE

Opioids such as morphine are widely used analgesics but are highly addictive. Emerging evidence implicates the gut microbiota in modulating opioid-associated pathophysiology. However, the global metabolic impact of morphine on gut microbial function and the causal transmissibility of morphine-induced dysbiosis remain to be fully elucidated.

METHODS

Adult C57BL/6 mice received repeated morphine administration for four consecutive days. Fecal metabolomic profiling was performed using integrated gas chromatography-mass spectrometry (GC/MS) and liquid chromatography-mass spectrometry (LC/MS) platforms. Gut microbial composition was analyzed by 16S rRNA gene sequencing and terminal restriction fragment length polymorphism (T-RFLP) profiling. To determine causality and transmissibility, fecal microbiota transplantation (FMT) was conducted from morphine-treated donor mice into antibiotic-depleted recipient mice.

RESULTS

Repeated morphine administration induced a profound global reprogramming of fecal metabolic profiles, with clear separation between morphine-treated and control mice. A total of 179 fecal metabolites were annotated. Morphine significantly increased diethylene glycol, N-acetyl-L-glutamic acid, and urea, while decreasing 3-aminoisobutyric acid, 2-aminobutyric acid, and pseudouridine. Pathway enrichment analysis revealed that amino acid-centered metabolic pathways, including branched-chain amino acid biosynthesis, arginine biosynthesis, and aminoacyl-tRNA biosynthesis, were the most prominently disrupted. Morphine exposure also induced a distinct dysbiotic microbial signature characterized by expansion of Enterococcus faecalis and Alistipes indistinctus, and depletion of Prevotella melaninogenica. Importantly, FMT from morphine-treated donors into microbiota-depleted recipients successfully transferred both the dysbiotic microbial structure and metabolic phenotype. Post-transplant recipient mice exhibited microbial profiles closely resembling morphine-treated donors, demonstrating that the morphine-induced dysbiosis is transmissible in the short term in the absence of direct drug exposure.

CONCLUSION

Repeated acute morphine exposure alters fecal amino acid and nitrogen metabolism and drives a transmissible dysbiotic state in the short term. These findings highlight a potential association between morphine exposure, metabolic remodeling, and gut dysbiosis, suggesting the gut microbiota may be a relevant factor in opioid-associated intestinal interactions.