Cocaine-administration in mice induced gut dysbiosis. Wild-type mice (C57BL/6) were administered cocaine (i.p, 20 mg/kg) or saline for seven consecutive days followed by euthanasia within 1 hr of the last injection. Fecal droppings and distal colon fecal matter were collected for 16S-rRNA sequencing. Several bacterial genus OTUs were altered in the presence of cocaine compared with controls as shown by the stacked bar (A) and the heat map (B) in pooled samples for each group. Cocaine administration affected microbial composition as shown by relative abundance of 16S rRNA transcripts in each individual animal at the genus level (C). UPGMA weighted unifrac and principal coordinates analysis (multidimensional scaling, MDS) show the clustering of microbiota from cocaine-administered mice (D,E respectively). S = Saline, C = cocaine, c = colon, d = droppings, col = colon, drop = droppings. n = 10/group.