To examine molecular changes associated with the changed behavioral sensitivity to cocaine, we assessed the transcriptional profile of a number of gene targets in the nucleus accumbens. In our antibiotic-treated animals given cocaine, we see alterations in the transcripts encoding both BDNF and its TrkB receptor (Fig. 6). BDNF signaling in the NAc has been repeatedly reported to alter behavioral responses to cocaine5051. Interestingly, numerous other studies examining the behavioral effects caused by alterations in the gut microbiome have also found changes in levels of BDNF in multiple brain structures4171827. While those studies were examining other brain regions and behavioral paradigms, the consistent finding that altered gut microbiota results in altered BDNF signaling lends credence to the idea that this is one of the ways in which changes in gut microbiota may be affecting behavior.
