Disentangling the specific contributions of different dorsal root ganglia neuron types to pain representation in the brain. - Pain is a multi-layered experience. It typically begins with nociception, the process by which noxious sensory signals are communicated through the peripheral and central nervous system. Peripheral signals are carried by various somatosensory neurons residing in the dorsal root ganglia (DRG) and trigeminal ganglia (TG). With the advent of innovative techniques like optogenetics and chemogenetics, researchers can now selectively modulate the activity of different classes of DRG neurons, offering insights on their specific roles in pain transmission. However, a comprehensive functional mapping of each molecularly defined DRG neuron types, especially in the context of chronic pain, has yet to be conducted. Furthermore, the effect of chemogenetic inhibition of DRG neurons on pain-induced neuronal activity in the brain has never been studied, leaving a gap in understanding the contribution of these primary afferent neurons to pain experience. I have successfully conducted the in vivo validation of a novel peripherally restricted designer receptor exclusively activated by designer drug (DREADD), in collaboration with Dr. Bryan Roth. This new tool enables us to use chemogenetics to inhibit DRG neurons without off-target effects. In this proposal, I aim to use this DREADD to: 1) establish a comprehensive functional map of molecularly defined DRG neuron types, 2) interrogate how distinct DRG neuron types can change the representation of pain in the brain, and 3) record and identify the cerebral neurons that directly respond to these peripheral manipulations. To create this functional map, I will combine our novel DREADD with mouse genetic tools to inhibit distinct classes of DRG neurons and assess their role in various types of pain. Then, to pinpoint the different brain structures that shut down their activity following peripheral inhibition, I will employ iDISCO+ whole-brain clearing, c-FOS immunostaining, and light-sheet microscopy. Lastly, to accurately record changes in the neuronal activity of relevant brain regions and identify antinociceptive neurons, I will combine two-photon in vivo microscopy with spatial transcriptomics. Altogether this project will determine whether different classes of DRG neurons can differentially contribute to acute and chronic pain experiences through the modulation of different neuronal ensembles in the brain. This research will occur in Dr. Grégory Scherrer’s laboratory at the University of North Carolina at Chapel Hill, an ideal environment for innovative research in the neurobiology of pain. With mentorship and guidance from esteemed neuroscientists Drs. Roth, Zylka, Ross, Schnitzer, and Ariel, this endeavor will greatly enrich my expertise in pain research, immersing me in cutting-edge techniques and concepts while filling critical gaps in knowledge in the pain field. Ultimately, this project will pave the way for my transition to an independent faculty position, ideally initiating my own laboratory program studying pain and associated comorbidities with a unique but holistic focus, the DRG-brain axis.
