DNA damage induced in hamster brains (cortex and medulla) by PA or clindamycin-induced bacterial overgrowth together with the protective effects of carnosine and L-carnitine. Neurotoxic effects of PA, bacterial overgrowth and ameliorating effects of both the supplements could be seen as significant changes in tail length (μm) and tail moments (Arbitrary units) (A &B respectively) and percentage changes in both (C &D). All figures are presented as mean±SE bars in the 8 studied groups compared to a control group. It is clear that orally administered PA was more neurotoxic than induced bacterial overgrowth. Carnosine was more protective than carnitine.