An analysis of the influence of sex hormones on Balb/c mice infected with Plasmodium berghei

• Castrated females had lower survival than all other female mice.
• On male mice, the administration of testosterone had a negative influence on survival.
• Despite increase in parasitemia, no repercussion on mice survival was observed.
• Loss of weight observed in almost all mice had no direct relation to parasitemia.
• Temperature and hemoglobin levels progressively declined in Balb-c mice.

Sex steroids can determine several responses in the clinical evolution of malaria. Seventy Balb-c mice were randomly distributed into 7 groups (10 mice per group): G1 to G6 corresponding to castrated females, castrated females that received estradiol cypionate, uncastrated females, castrated males, castrated males that received intramuscular testosterone decanoate and uncastrated males infected with Plasmodium berghei, and G7, the control group. The mice were evaluated with regard to survival, parasitemia, temperature, body weight, hemoglobin level (anemia) and splenic index. Castrated infected females had lower rates of survival. In the castrated male, the administration of testosterone had a negative influence on survival. There was a progressive increase in parasitemia without repercussions for survival. Castration had a significant influence on weight gain in females. Weight loss was observed in all mice, except those in groups G2 and G5, although this bore no direct relation to parasitemia. A significant and progressive decline in temperature and hemoglobin levels occurred in mice over the course of their infection, which differed from the G7 group. The weight of the spleen in relation to total body weight did not differ among the groups of infected mice, but was significantly higher than it was for the control group.