Using optogenetics to assess neuroendocrine modulation of heart rate in Drosophila melanogaster larvae
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The Drosophila melanogaster heart has become a principal model in which to study cardiac physiology and development. While the morphology of the heart in Drosophila and mammals is different, many of the molecular mechanisms that underlie heart development and function are similar and function can be assessed by similar physiological measurements, such as cardiac output, rate, and time in systole or diastole. Here, we have utilized an intact, optogenetic approach to assess the neural influence on heart rate in the third instar larvae. To simulate the release of modulators from the nervous system in response to environmental influences, we have directed expression of channel-rhodopsin variants to targeted neuronal populations to assess the role of these neural ensembles in directing release of modulators that may affect heart rate in vivo. Our observations show that the activation of targeted neurons, including cholinergic, dopaminergic, and serotonergic neurons, stimulate the release of cardioactive substances that increase heart rate after the initial activation at both room temperature and in a cold environment. This parallels previous studies suggesting these modulators play a crucial role in altering heart rate when applied to exposed hearts and adds to our understanding of chemical modulation of heart rate in intact Drosophila larvae.
KeywordsCardiac Optogenetics Drosophila melanogaster Heart rate Modulators
GAL4 driver targeting expression to cholinergic neurons (choline acetyltransferase)
Less sensitive channel-rhodopsin-2
Central nervous system
GAL4 driver targeting expression to dopaminergic neurons (pale)
GAL4 driver targeting expression to class IV dendritic arborization sensory neurons (pickpocket)
GAL4 driver targeting expression to serotonergic neurons (Tryptophan hydroxylase)
This work was funded by G. Ribble fellowship from Department of Biology, Univ. of KY (A.O.), A. M. was supported by KY IDeA Network of Biomedical Research Excellence Grant #P20GM103436, funding provided by Research and a summer research undergraduate fellowship from the Outreach Center for Science and Health Career Opportunities at the University of Kentucky (JS) and personal funds (RLC).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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