Abstract Drug addiction is an intractable psychiatric disorder exerting a deleterious impact on public health in the United States and beyond. Influences of the gastrointestinal tract (GI) on neuropsychiatric disorders are recognized, and several studies supported that the gut microbiome plays a massive role in brain-behavior function. A common variant in the gene that encodes brain-derived neurotrophic factor (BDNF) (Val66Met) is of considerable interest due to the extensive role of BDNF in neurodevelopment and opioid abuse. In particular, there is a gap in knowledge about the relationship between addiction and gut microbiome in adolescence. Therefore, it is still unclear how oxycodone affects the gut microbiome and metabolome in adolescents, one potential mechanism that may explain the link between brain-gut opioid-induced dysbiosis is BDNF. The goal of this proposal is to validate the role of BDNF in adolescent microbiome dysbiosis caused by chronic oxycodone use. The specific aims of this proposal will serve as a transitional career steppingstone and preliminary research for R01 proposals to determine 1) adolescent gut microbiome changes associated with oxycodone dependence and withdrawal in Val66met mice, 2) establish the therapeutic value of fecal microbiota transplants (FMT) on BDNF Val66Met mice on oxycodone-induced-dysbiosis, and 3) to analyze levels of SCFA and kynurenine metabolites in a non-invasive in vivo model of voluntary oral oxycodone-self administration (SA). The novelty and innovation of this proposal will cover gaps in knowledge about the effects of oxycodone-induced dysbiosis on adolescent microbiomes. It will also be the first study to evaluate the direct effect of BDNF deficiency and opioid-induced dysbiosis in context with the adolescent microbiome-gut-brain axis. This understanding is needed for the development of future interventions to prevent or treat substance abuse. Finally, the project will support the Research Project Leader’s future success in targeting extramural funding (e.g., NIH R25 or R01 funding) and establishing a new direction of research program.