Does juvenile hormone prompt males to oxidative stress?

Abstract

In invertebrates, it has been recently reported that secondary sexual characteristics (SSC) reflect the antioxidant defense of their bearers, but it is not known what physiological link maintains the honesty of those signals. Here, we use the damselfly Hetaerina americana to test whether Juvenile Hormone plays such a role. First, we analyzed whether oxidative damage is a real threat in natural damselfly populations by examining the accumulation of oxidized guanines as a function of age in males. Then, we injected paraquat (a pro-oxidant agent) and added the Juvenile Hormone analog Methoprene (JHa) to the experimental group and the JHa vehicle (acetone) to the control group, to determine whether JHa increases the levels of pro-oxidants and antioxidants. We found that DNA oxidation increased with age, and levels of hydrogen peroxide and superoxide dismutase, but not catalase or glutathione, were elevated in the JHa group compared to the control group. We propose that Juvenile Hormone is a mediator of the relationship between SSC and antioxidant capacity and based on the literature, we know that JHa suppresses immune response. We therefore suggest that Juvenile Hormone is a molecular mediator of the general health of males, which is reflected in their SSC.