Drosophila insulin like peptides and TMS

On January 28^th, 2020 Professor Dan Cavanaugh presented his research on circadian rhythms and drosophila. In the study “A circadian output center controlling feeding: fasting rhythms in Drosophila”, numerous cells were found to have critical functions in the regularity of feeding rhythms. This research article further explains the role of cells called the SIFa cells found in the Pars Intercerebralis (PI) of the Drosophila Melanogaster as well as Drosophila insulin-like peptides (DILPs) and diuretic hormone 44 (DH44). The PI region of the Drosophila brain is suggested to have homologous function to the hypothalamus of the mammalian brain. The Drosophila insulin-like peptides were presented in this study as possible influences for feeding and metabolism. The study describes these DILP cells as significant factors for food consumption as activation of these cells shows an increase of feeding. 

I was particularly interested in the function and further exploration of the DILPs as the activation of these cells showed increased food intake. I immediately became curious as to how this may be used to produce positive results for those suffering from eating disorders. If there is a region in the mammalian brain that is functionally similar to the Pars Intercerebralis of the Drosophila, this suggests that perhaps activation of this region may produce those effects like the activation of the DILPs. Dr. Cavanaugh’s research study does not include specific information towards the findings of cells analogous to the DILPs, however the study does include a comparison to the mammalian hypothalamus. Using this information and the spatial resolution of Transcranial Magnetic Stimulation, this could be a potential method for stimulating and activating these regions. 

In the research article “Targeting Neural Endophenotypes of Eating Disorders with Non-Invasive Brain Stimulation”, Katharine A. Dunlop et al. explains the possibility of this method in their experiment. The study describes the effects transcranial magnetic stimulation can offer as it non-invasively modulates the cortical excitability of targeted regions in the brain. With the intricate consequences that follow eating disorders, treatments can be difficult and ineffective. This study describes how TMS would then offer another potential treatment for those that are treatment resistant. Just as Dr. Cavanaugh discussed the region in the Drosophila PI being similar to the human hypothalamus, this study suggests that endophenotypes can be connected to their neurobiological substrates using neuroimaging techniques and then become potential targets for treatment. Both studies explore regions of the brain that contribute to food intake in the human brain. Dr. Cavanaugh’s study explores the presence and activation of neuronal cells which may play a significant role in overall food consumption while Dunlop’s study investigates the endophenotypes of eating disorders and the effects of activation and stimulation on these regions in the brain. 

Dunlop, Katharine A et al. “Targeting Neural Endophenotypes of Eating Disorders with Non-invasive Brain Stimulation.” Frontiers in neuroscience vol. 10 30. 16 Feb. 2016,

doi:10.3389/fnins.2016.00030 

Dreyer, Austin & Martin, Madison & Fulgham, Carson & Jabr, Daniel & Bai, Lei & Beshel, Jennifer & Cavanaugh, Daniel. (2019). A circadian output center controlling feeding: Fasting rhythms in Drosophila. PLOS Genetics. 15. e1008478. 10.1371/journal.pgen.1008478.