Assessing The Role of Juvenile Hormone in The Blood Brain Barrier For Male Courtship in Drosophila melanogaster

Juvenile hormone (JH) is one of the major insect hormones involved in many physiological processes with roles in development as well as reproduction, metamorphosis, caste determination, behavior, diapause, and polyphenisms. Previous research has shown that JH is required at normal physiological levels for proper male courtship. However, the target cells responding to JH levels modulating courtship behavior were unknown. It is expected that the JH target cells contain the JH receptor MET and/or GCE along with proteins that might interact with the JH-Met complex. RNAseq studies of isolated blood brain barrier (BBB) cells have shown that both proteins are present in the BBB. This study addresses the question of whether JH is required in the BBB for proper male courtship and whether the intracellular JH receptors Met and gce are needed in the BBB for male courtship. The first question was addressed by conditionally reducing the levels of JH in the BBB of mature males through the action of the JH degrading enzyme juvenile hormone esterase and assaying their courtship behavior. The second question was addressed by reducing the levels of Met or gce in the BBB of adult males by interfering RNA followed by assaying the courtship behavior of virgin males.

Our results show that JH is required in the BBB for proper male courtship, a finding which was reinforced by rescue with the JH analog, Methoprene. We further found that Met is required in the BBB for male courtship, although gce is not. These findings suggest an important role for JH signaling through the JH receptor Met in the BBB for male courtship.