MECHANISMS FOR OMEGA-6 MODULATION OF PRIMARY AFFERENT NOCICEPTORS

Although medical recommendations about diet are made for cardiovascular disease and diabetes, this is notthe case for most pain disorders. However, diet could be a risk factor for chronic pain conditions as linoleic(LA) and arachidonic (AA) acid are essential omega-6 polyunsaturated fatty acids (?-6 PUFA), where their cellmembrane levels are regulated by dietary intake. Importantly, the oxidized metabolites of LA or AA have potentbiological actions in activating targets such as transient receptor potential (TRP) channels, which areexpressed on primary afferent nociceptors. Thus, the incorporation and release of omega-6 PUFAs fromcellular membranes plays a key role in regulating nociceptor activities, including pain. Our central hypothesis isthat dietary omega-6 PUFA-induced increase in nociceptor activities is mediated by the activity of PLA2subtypes, resulting in activation of neuronal receptors/channels. This is supported by mulitple lines ofpreliminary data using a robust set of behavioral, electrophysiologic, imaging, and RNAseq methodologies.Aim 1. Determine which subclasses of DRG afferents mediate HFD-induced nociception. We will use sixCre+/--DTA+/- mouse lines generated for the conditional ablation of neurons expressing Nav1.8 (allnociceptors), TrpV1 (nociceptors), CGRP (peptidergic nociceptors), Mrgprd (non-peptidergic nociceptors),TrkC (A? low threshold mechanoreceptors (LTMR)) and TrkB (A? LTMR fibers) (Table 1). Mice will be fed aHigh omega-6 PUFA diet (H6D) or a low omega-6 diet (L6D) and behavioral, electrophysiologic and lipidomicoutcomes will be measured. (Popular ketogenic diets are different as they are low omega-6 PUFA)Aim 2: Determine the effects of H6D on DRG neuronal membrane lipid content and PLA2 isozyme(s)expression and mechanisms for regulating nociceptor activities.Aim 3: Determine whether switching to a L6D or to a high omega-3:Low omega 6 diet reverses the effects of aH6D on nociception.This project has substantial scientific and medical significance as the central hypothesis predicts that H6D willpredispose patients to chronic pain conditions and offers new targets for analgesic drug development.