Abstract:
To determine if testosterone mediates susceptibility differences
between male and female mice infected with Schistosoma japonicum,
testosterone was either removed or exogenously applied in groups of
BALB/C mice that were infected with the same number of cercariae. The
mice were then monitored for host survival, worm burden, organomegaly,
and egg count. By eight weeks after infection, 80% of the members of the
negative control group or the mice with no testosterone source (castrated
males and untreated females) were dead, while only 45% of the members of
the experimental group or the mice treated with exogenous testosterone
(testosterone-treated castrates and testosterone-treated females) had died.
On the other hand, the positive control group or the mice with endogenous
testosterone source (normal males) exhibited the same proportion of dead
mice (80%) as the negative control group. The mean number of worms
recovered from the negative control group was significantly higher than
those from the experimental and positive control groups. The number of
eggs counted in the liver sections of the mice correlated strongly with the
worm burden, significantly more eggs were present in the liver sections of
the mice in the negative control group than those in the experimental and
positive control groups. The hepatomegaly exhibited by the mice likewise
correlated with worm burden, but the degree of splenomegaly did not differ
significantly between groups. Thus, the sex-based susceptibility difference
observed in male and female mice infected with the same number of
cercariae appears to be associated to the presence of testosterone.
