Understanding Neurotransmitter Identity and Plasticity in the Circadian Clock Network of Drosophila.
The clock network in Drosophila is one of the best characterized behavioral circuits and is responsible for circadian control of various bodily functions including sleep, activity, feeding and more. As such, it is important to identify the neurotransmitters used by neurons in this circuit to communicate. In this thesis, I use RNAscope in combination with IHC to quantify expression levels of VAChT, Gad1, and VGlut in LNv and DN1p neurons of the clock network. I also use this approach to quantify expression levels of these markers in 53D10 neurons of the AMMC which may be a sleep-promoting, output pathway for the clock network. I found all three markers well represented in LNv and 53D10 neurons and VAChT and VGlut in DN1p’s. Additionally, for all three of these populations, I found a good fraction of cells that co-express markers for multiple classical neurotransmitters. This is the first time clock neurons have been shown to have this property. Since the neurons in the clock network are thought to change their activity with the time of day, they are a good model for investigating which conditions, if any, enable neurotransmitter plasticity in adult Drosophila. Preliminary data from my thesis suggest that changes in light/dark cycles of entrainment may cause changes in VGlut expression in LNv neurons of the clock network.