Figure 4. Effect of menadione pretreatment on Plasmodium berghei ANKA infections in mice.

(a) C57BL/6 mice were pretreated with intraperitoneal injections of 150 mg kg⁻¹ menadione (MD) or PBS (mock) on days −3, −2 and −1. On day 0 mice were intravenously infected with 10⁶ P. berghei-infected erythrocytes (iRBC). One group of mice received only MD pretreatment and was not infected with parasites (control). The number of mice per treatment group is indicted in parenthesis. (b) Time course of parasitaemia in MD-pretreated and untreated mice. The mean±s.e.m. of 15 mice per treatment group is shown. An F-test revealed no statistically significant differences between the two time courses. (c) Representative T2*-weighted magnetic resonance images of an MD-pretreated and an untreated P. berghei-infected mouse. The region of the olfactory bulb is magnified and microhaemorrhages are indicated by white arrows. Graph: quantification of the total volume of microhaemorrhages in the olfactory bulb. The mean±s.e.m. of three mice per treatment group is shown (P<0.01, according to Student's t-test). In this and in the following subfigures, mice were examined at day 6 post infection. (d) Histological examination of brain sections. Representative sections of the peripheral regions of the olfactory bulb, covering part of the periglomerular and mitral cell layer, from a MD-pretreated and an untreated infected mouse are shown. Note the reduced number of microhaemorrhages in the periglomerular layer (black arrows) from MD-pretreated infected mice compared with untreated infected mice. Scale bar, 100 μm (e) Representative T1-weighted subtraction magnetic resonance images after injection of a contrast agent, revealing less blood–brain barrier disruption in MD-pretreated infected mice as compared with untreated infected mice. A representative image of the brain of an uninfected and untreated mouse is shown as a negative control (control). The colour scale is a relative measure of blood–brain barrier disruption. (f) Vascular permeability of brains was further assessed by Evans Blue injection. Representative images of brains are shown for each group.