Figure 2. Knockdown of intestinal bacteria does not alter cocaine metabolism.

(a) Serum levels of the cocaine metabolite benzoylecygonine 30, 60, or 90 minutes after a single high-dose injection of cocaine did not differ between control (H₂O) and antibiotic-treated (Abx) mice (n = 4–5/group/timepoint). (b) Levels of benzoylecygonine 30 minutes after a 5 mg/kg injection of cocaine also did not differ between groups (n = 3 H₂O, 5 Abx). (c) Levels of serum corticosterone in animals treated with antibiotics via the drinking water did not differ between groups (n =  10 H₂O, 10 Abx).