The Effect of Fentanyl Abuse on the Gut Microbiota Pattern, Inflammation, and Metabolic Alterations in a Fentanyl...

Introduction: This study examines the effects of fentanyl misuse on gut microbiota, inflammation, and metabolic pathways using a rat model. As the opioid crisis, driven by synthetic opioids like fentanyl, escalates, identifying new biomarkers, and therapeutic strategies becomes crucial to mitigate its negative impacts and rising overdose cases. Methods: This study was done using species-specific 16S rRNA gene profiling through absolute real-time PCR techniques, alongside relative real-time PCR analysis for inflammatory and metabolic markers and liquid chromatography-mass spectrometry (LC-MS) for metabolite quantification. To visualize the correlations between microbial abundance and inflammatory/metabolic markers, Spearman/Pearson correlation analyses were performed. Results: Fentanyl treatment increased Clostridium sensu stricto (p=0.69) and Bacteroides fragilis (p=0.04), while Faecalibacterium prausnitzii (p=0.14) and Lacticaseibacillus rhamnosus (p=0.14) showed a tendency to decrease. Additionally, fentanyl-treated rats exhibited heightened levels of pro-inflammatory cytokines (IL-1β, p=0.01; TNF-α, p=0.083; IL-6, p=0.17) and increased expression of toll-like receptors (TLR-2, p=0.005; TLR-4, p=0.001), indicating intestinal inflammation. Metabolic pathway analysis revealed significant alterations, including increased BCoAT expression (p  < 0.001) and decreased tph1 expression (p  < 0.001) in fentanyl-treated rats. LC-MS analysis indicated a significant reduction in butyrate levels (45.49 ± 7.82; 73.52 ± 5.4 µM; p  < 0.001), suggesting impaired short-chain fatty acid production and potential gut barrier integrity issues. Tryptophan levels were also significantly lower (14.96 ± 1.3; 22.38 ± 2.1 µM; p  < 0.001), indicating possible disruptions in serotonin synthesis, while deoxycholic acid levels increased (106.1 ± 7.3; 77.35 ± 3.5 µM; p  < 0.001), suggesting altered bile acid metabolism contributing to gut inflammation. Leucine levels (31.8 ± 1.5; 30.67 ± 1.6 µM; p=0.15) remained comparable between groups. Conclusion: This study reveals complex relationships between fentanyl consumption, gut microbiota alterations, gut inflammation, and metabolic functions. The identified changes in specific bacterial species and inflammatory markers suggest a potential mechanism by which fentanyl may exacerbate gut inflammation and disrupt metabolic pathways, highlighting the importance of these dynamics in understanding the microbiota importance and opioid dependance.