Accession Number : AD1034593

Title :   Electrophysiological and Behavioral Evaluation of C-LTMR Plasticity Induced by Spinal Cord Injury: Transformation from Pleasure to Pain Afferents

Descriptive Note : Technical Report,30 Sep 2015,29 Sep 2016

Corporate Author : Emory University School of Medicine Atlanta United States

Personal Author(s) : Garraway,Sandra M ; Hochman,Shawn

Full Text :

Report Date : 01 Oct 2016

Pagination or Media Count : 13

Abstract : The overall objective of the study is to test the hypothesis that C-low threshold mechanoreceptors (C-LTMRs) are transformed into allodynia-encoding nociceptors after SCI. Because C-LTMRs can be selectively identified by their expression of tyrosine hydroxylase (TH), all studies were done in adult transgenic TH-Cre mice. During the year 1 funding period, we made significant progress with the proposed experiments. Using the ex-vivo skin-nerve preparation, C-LTMR-evoked neural responses were recorded in dorsal cutaneous nerves following mechanical and optogenetic stimulation of the trunk skin. Serendipitously, we found that our TH-Cre mice also express TH in faster conducting, myelinated A delta-LTMRs, afferents that innervate the same hair follicles as C-LTMRs. Preliminary studies further showed that receptive fields of C-LTMRs (and A delta-LTMRs) are enhanced after SCI. Simultaneous behavioral studies showed that SCI acutely increased respiratory rates (RR), and that brush stimulation induced a slight increase in RR at 21 days after SCI. However, as the studies were done in TH-Cre mice, we are unable to specifically associate these responses to C-LTMRs. Due to the lack to specificity of our TH-Cre strain, future electrophysiological and behavioral studies will be undertaken in an inducible Cre strain (TH-CreER). This will enable us to more selectively target C-LTMRs.

Descriptors :   SPINAL CORD , wounds and injuries , pain , receptor sites (physiology) , TYROSINE , STIMULATION (PHYSIOLOGY) , ELECTROPHYSIOLOGY , SYMPATHETIC NERVOUS SYSTEM , heart rate , behavior

Subject Categories : Medicine and Medical Research
      Anatomy and Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE