Influence of Chlorpromazine on Eryptosis, Parasitemia and Survival of Plasmodium berghei Infected Mice
Chlorpromazine has previously been shown to trigger suicidal erythrocyte death or eryptosis, which is characterized by exposure of phosphatidylserine at the erythrocyte surface and cell shrinkage. Premature suicidal death of infected erythrocytes is in turn considered to delay development of parasitemia and thus favourably influence the clinical course of malaria. The present experiments have been performed to explore whether chlorpromazine influences in vitro parasite growth and eryptosis of Plasmodium falciparum infected human erythrocytes and in vivo parasitemia and survival of P. berghei infected mice. Phosphatidylserine was estimated from annexin V binding and cell volume from forward scatter in FACS analysis. In vitro infection of human erythrocytes increased annexin binding and decreased forward scatter, effects augmented in the presence of chlorpromazine (≧10 µM). Chlorpromazine did not significantly alter intraerythrocytic DNA/RNA content but significantly (≧1 µM) decreased in vitro parasitemia. In chlorpromazine treated mice erythrocytes were more rapidly cleared from circulating blood than in nontreated mice. Parasitemia in P. berghei infected mice was significantly decreased (from 50 % to 28 % of circulating erythrocytes 22 days after infection) and mouse survival significantly enhanced (from 0 % to 80 % 30 days after infection) by addition of 1 mM chlorpromazine to the drinking water from the first day of infection. In conclusion, chlorpromazine favourably influences the course of malaria, an effect at least partially due to stimulation of suicidal erythrocyte death.