Nitric oxide (NO) is a gaseous signaling molecule synthesized by the enzyme nitric oxide synthase (NOS). NO functions as a brain neurotransmitter and immune system defense molecule. Animals undergoing an inflammatory response, such as from bacterial infection, exhibit changes in behavior. We are using the cricket Acheta domesticus to explore the role NO may play in producing such changes. Crickets exhibit well characterized agonistic behavior; when two male crickets come into contact they fight until a winner (dominant) and loser (subordinate) are established. We found that male crickets injected with bacterial lipopolysaccharide (LPS) were more likely to lose fights against control males. We hypothesize that NO, produced during the LPS-induced inflammatory response, caused these males to lose. To test this, we are using qPCR to quantify NOS expression in the fat body (FB), an important insect immune tissue, and in the brain, since changes in brain NO levels are known to impact male aggression. We expect that LPS-injected crickets will have up-regulated NOS expression, and increased NO levels, in these tissues relative to controls. Our first goal, however, was to measure basal NOS expression in these tissues. We found that basal NOS expression in FB was higher in females than males, while brain NOS expression was higher in males compared to females. These sex differences are especially interesting since females are less aggressive than males and may produce a stronger immune response. We will now collect tissue from LPS injected crickets to examine NOS expression in the FB and brain during an inflammatory response. This work has been relevant to my intended career because I plan to pursue a career in medicine, specifically neurosurgery or neurology. NOS and its regulation of NO may have many implications about behavioral regulation and mood disorders in humans, which I hope to further explore.
Author: Lauren Schaffer
Advisor: Kathleen Killian, Biology
Graduate Advisor: Siva Athitya Lakshamana Vijayarajan, Biology
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