A Snapshot seminar hosted by the School of Physiology, Pharmacology and Neuroscience
Lukasz: Feeding is critical for survival and is orchestrated through the interplay of brain and gut signals. A subset of brain structures localised in the hypothalamus and brainstem coordinate both the amount and circadian times of day that food is consumed. Although the primary circadian clock is localised in the suprachiasmatic nuclei of the hypothalamus (SCN), local extra-SCN timekeeping mechanisms are important for circadian control of physiology including the daily patterning of feeding. Intrinsic timekeeping mechanisms in the hypothalamic structures implicated in the control of food intake are much researched, but circadian rhythms in the brainstem feeding centres are under-explored. Thus, we focus on evaluating potential local clock control over the brainstem’s dorsal vagal complex (DVC). Real-time bioluminescence recording of clock gene expression (PER2::LUC) ex vivo reveals that in developing and adult DVC, PER2 rhythms can be sustained for days to weeks, even when isolated from the SCN. Assessing neuronal activity in DVC brain slices on a multielectrode array recording platform, shows that the PER2 rhythms are accompanied by electrophysiological rhythms with peak neuronal firing at late day. Importantly, assessment of gene expression by qPCR and RNAscope in situ hybridisation reveals that core clock genes are rhythmically expressed in the DVC in vivo with their expression present in neurochemically diverse neuronal and non-neuronal populations. Moreover, our recent results show that these rhythms in clock gene expression result in daily patterning of secondary genes, e.g., those coding many neurotransmitter receptors. Manipulating the rodent diet reveals that this temporal variation in DVC neurophysiological activity is notably dampened by consumption of high-fat food. Also, restricting the time of food availability affects the phasing of DVC oscillation in vivo, in some, but not all DVC clocks. Collectively, these studies point to how circadian mechanisms and diet alter molecular and cellular activity in the DVC. Our research adds to a growing literature on the importance of understanding.
Robin: Computational molecular modelling/simulation allows the visualisation of biological systems at the atomic level. These methods have recently emerged as powerful tools for investigating a range of biological processes, enabling unparalleled insights into the mechanisms underpinning important cellular events. Through these insights specific hypotheses can be generated, which can subsequently be validated and given physiological context using experimental analyses. As such, computational modelling serves as a tool in understanding the mechanistic basis of various diseases, as well as offering valuable support in the development of targeted therapeutic interventions. In this talk, I will give an overview of these methods and how my lab will leverage them, in close collaboration with experimental colleagues, to answer a range of exciting biological and pharmacological questions over the coming years.