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Functional neurokinin and NMDA receptor activity in an animal naturally lacking Substance P: the naked mole-rat

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Item Type:Article
Title:Functional neurokinin and NMDA receptor activity in an animal naturally lacking Substance P: the naked mole-rat
Creators Name:Brand, A. and Smith, E.S.J. and Lewin, G.R. and Park, T.J.
Abstract:Naked mole-rats are extremely unusual among mammals in that their cutaneous C-fibers lack the neuropeptide Substance P (SP). In other mammals, SP plays an important role in nociception: it is released from C-fibers onto spinal neurons where it facilitates NMDA receptor activity and causes sensitization that can last for minutes, hours or days. In the present study, we tested the effects of intrathecal application of: 1) SP, 2) an SP antagonist (GR-82334), and 3) an NMDA antagonist (APV) on heat-evoked foot withdrawal. In the naked mole-rat, at a high enough concentration, application of SP caused a large, immediate, and long-lasting sensitization of foot withdrawal latency that was transiently reversed by application of either antagonist. However, neither SP nor NMDA antagonists had an effect when administered alone to naïve animals. In contrast, both antagonists induced an increase in basal withdrawal latency in mice. These results indicate that spinal neurons in naked mole-rats have functional SP and NMDA receptors, but that these receptors do not participate in heat-evoked foot withdrawal unless SP is experimentally introduced. We propose that the natural lack of SP in naked mole-rat C-fibers may have resulted during adaptation to living in a chronically high carbon dioxide, high ammonia environment that, in other mammals, would stimulate C-fibers and evoke nocifensive behavior.
Keywords:Evoked Potentials, Food, Immunohistochemistry, Nerve Fibers, Neurokinin-1 Receptors, N-Methyl-D-Aspartate Receptors, Peptide Fragments, Spinal Injections, Substance P, Animals, Mice, Mole Rats, Rats
Source:PLoS ONE
Publisher:Public Library of Science
Page Range:e15162
Date:21 December 2010
Official Publication:https://doi.org/10.1371/journal.pone.0015162
PubMed:View item in PubMed

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