Neural Mechanism Of Neuropeptide Drosulfakinin In Regulating Female Receptivity In Drosophila

Reproductive behavior is a universal innate behavior in animal kingdom and it’s the foundation of survival and reproduction.The study of flies has taught us a lot about the molecular and neural mechanism that control reproductive behavior.In Drosophila melanogaster,a number of genes controlling male courtship have been identified and corresponding neural circuits have been dissected,whereas the molecular and circuit mechanism underlying female sexual behavior is less clear,especially the roles of neuropeptides in female mating behavior remain largely unexplored.In this study,we investigate the molecular and neural mechanism that the neuropeptide Drosulfakinin(DSK)involves in modulating female sexual behavior.We found that Dsk null mutant or RNAi knock down of Dsk displayed reduced copulation rate,however,overexpression of Dsk in DSK neurons increased copulation rate and genetic rescue experiment could restore the decreased receptivity level of Dsk mutant female to normal level.Furthermore,activation and inactivation of DSK neurons could promote and inhibit female sexual behavior,respectively.In addition,knock out of CCKLR-17D3 or RNAi knock down of CCKLR-17D3 reduced mating success rate in females.We found that knock-out of CCKLR-17D3 could block the increased levels of female receptivity caused by activating DSK neurons.Thus,DSK neurons rely on its receptor CCKLR-17D3 to regulate female sexual receptivity.Eight DSK neurons were classified two types(DSK-M and DSK-L)based on the location of the cell bodies in female brains.To further distinguish if both types are or only one type of DSK neurons was involved in regulating female sexual behavior,we used intersectional strategy to subdivide DSK neurons and manipulate DSK-M and DSK-L separately.And we found that DSK-M neurons,rather than DSK-L neurons,were responsible for regulating female sexual receptivity.In addition,we detected that Dsk-expressing neurons had potential synaptic connection with R71G01GAL4 neurons via GRASP and trans-Tang approaches,and DSK neurons were the functional targets of R71G01-GAL4 neurons in controlling female sexual behavior by performing behavioral epistasis.Anatomical registration,EM data and electrophysiology experiments unambiguously demonstrated that Dsk-expressing neurons received input from sex-promoting pC1 neurons labeled by R71G01-GAL4.Together,we systematically investigate Dsk-mediated neuromodulation of female sexual receptivity in the molecular and neural circuit levels.Drosulfakinin(DSK)is an ortholog of Cholecystokinin(CCK)in mammals,which provide insight for us to understand the mating behavior of females in other insects or mammals.