A Novel Method to Quantify Histochemical Changes Throughout the Mediolateral Axis of the Substantia Gelatinosa After Spared Nerve Injury: Characterization with TRPV1 and Substance P

Corder, Gregory; Siegel, Andrew; Intondi, Allison B.; Zhang, Xing; Zadina, James E.; Taylor, Bradley K.

doi:10.1016/j.jpain.2009.09.008

« Previous Next »The Journal of Pain
Volume 11, Issue 4 , Pages 388-398, April 2010

A Novel Method to Quantify Histochemical Changes Throughout the Mediolateral Axis of the Substantia Gelatinosa After Spared Nerve Injury: Characterization with TRPV1 and Substance P

Gregory Corder
- Department of Physiology, School of Medicine, University of Kentucky Medical Center, Lexington, Kentucky
Andrew Siegel
- Department of Pharmacology, School of Medicine, Tulane University, New Orleans, Louisiana
Allison B. Intondi
- Department of Pharmacology, School of Medicine, Tulane University, New Orleans, Louisiana
Xing Zhang
- Department of Medicine, School of Medicine, Tulane University, New Orleans, Louisiana
James E. Zadina
- Department of Pharmacology, School of Medicine, Tulane University, New Orleans, Louisiana
- Department of Medicine, School of Medicine, Tulane University, New Orleans, Louisiana
- SE Louisiana Veterans Health Care System, New Orleans, Louisiana
Bradley K. Taylor
- Department of Physiology, School of Medicine, University of Kentucky Medical Center, Lexington, Kentucky
- Address reprint requests to Bradley K Taylor, University of Kentucky Medical Center, 800 Rose Street, Department of Physiology, Lexington, KY 40536-0298.

Received 12 June 2009; received in revised form 4 September 2009; accepted 21 September 2009.

Abstract

Nerve injury dramatically increases or decreases protein expression in the spinal cord dorsal horn. Whether the spatial distribution of these changes is restricted to the central innervation territories of injured nerves or could spread to adjacent territories in the dorsal horn is not understood. To address this question, we developed a simple computer software-assisted method to precisely distinguish and efficiently quantify immunohistochemical staining patterns across the mediolateral axis of the dorsal horn 2 weeks after transection of either the tibial and common peroneal nerves (thus sparing the sural branch, spared nerve injury, [SNI]), the tibial nerve, or the common peroneal and sural nerves. Using thiamine monophosphatase (TMP) histochemistry, we determined that central terminals of the tibial, common peroneal, sural, and posterior cutaneous nerves occupy the medial 35%, medial-central 20%, central-lateral 20%, and lateral 25% of the substantia gelatinosa, respectively. We then used these calculations to show that SNI reduced the expression of SP and TRPV1 immunoreactivity within the tibial and peroneal innervation territories in the L4 dorsal horn, without changing expression in the uninjured, sural sector. We conclude that SNI-induced loss of SP and TRPV1 in central terminals of dorsal horn is restricted to injured fibers. Our new method enables direct comparison of injured and uninjured terminals in the dorsal horn so as to better understand their relative contributions to mechanisms of chronic pain.

Perspective

A simple computer software-assisted algorithm was developed to precisely distinguish and efficiently quantify immunohistochemical staining patterns across the mediolateral axis of the dorsal horn after distal sciatic-branch transection. This method will facilitate a better understanding of the relative contribution of injured and uninjured terminals to mechanisms of chronic pain.

Key words: Dorsal horn, hyperalgesia, pain, immunohistochemistry, rat