Presentation Details
| Mice that lack trigeminal thermosensory afferents retain sensitivity to oral temperatures Catori J.Roberts, Rosalie C.Maltby, Christian H.Lemon. University of Oklahoma, Norman, OK, USA |
Abstract
The transient receptor potential vanilloid 1 (TRPV1) ion channel senses noxious temperatures (>43°C) and chemical stimuli (capsaicin) and is an embryonic marker for all thermosensitive neurons including those expressing TRMP8 and TRPA1. Here, we used a mouse line with diphtheria toxin fragment A (DTA) expressed in all embryonic cells expressing TRPV1 to ablate them. Previous studies have shown that TRPV1 lineage ablation leads to temperature and chemical insensitivity on the extremities (Mishra et al., 2011). However, it is unknown if this leads to trigeminal thermal insensitivity in the oral cavity. To test this, C57BL/6J (n = 9; B6) and TRPV1-DTA (n = 10; DTA) mice were proffered water at a reference temperature (30°C or 35°C) and randomly selected test temperature (e.g., 3°, 15°, 40°, or 43°C) in a fluid temperature controlled brief access licking assay over 11 days. Next, they were exposed to increasing concentrations of Ally isothiocyanate (AITC: 0, 0.003, 0.01, 0.03, 0.1, 0.3, and 1mM) and then capsaicin (0, 0.003, 0.03, 0.06, and 0.1 mM). Results showed that the DTA mice retained sensitivity to oral temperatures with some differences between lines. For example, both B6 and DTA mice preferred 30°C water over warmer temperatures (main effect, p <0.05) whereas water temperatures less than 30°C were more strongly preferred in DTA mice (interaction, p = 0.013). This result suggests that the DTA group is not insensitive to temperatures exposed to the oral cavity, implying non-trigeminal afferents may participate in oral temperature sensing. We plan to use RNA Scope (In-situ hybridization) to fluorescently label and map the presence or lack thereof of thermoTRP ion channels in the trigeminal ganglion of both groups as well as expand studies with new subject groups.
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No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author.
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