Bailey AL, Bennett G, Ribeiro-da-Silva A (2004) Investigation of the functional role of non-peptidergic primary afferent sensory fibres in the transmission of pain related information. Neuroscience 2004 Abstracts 484.1. Society for Neuroscience, San Diego, CA.
Summary: It is well established that small diameter, unmyelinated, primary afferent C-fibres can be divided into two neurochemically defined populations, one that contains neuropeptides such as Substance P (SP) and Calcitonin-gene related peptide (CGRP) and the other which binds Isolectin B4 (IB4) and is relatively peptide negative. A great deal of circumstantial evidence indicates that the non-peptidergic afferents play a functionally distinct role in pain transmission compared to peptidergic afferents. Indeed, the concept of two distinct subpopulations of C-fibres would indicate the occurrence of parallel processing in pain pathways. However, the functional role of non-peptidergic afferents in the transmission of pain-related information is still unclear. In an attempt to clarify their functional role, we decided to study the development of hyperalgesia and allodynia in adult male Sprague-Dawley rats with selective ablation of IB4-binding, non-peptidergic afferent input to the dorsal horn. To achieve this, we injected IB4 conjugated to Saporin (SAP) into the left sciatic nerve and examined both neurochemical and behavioural changes over a month’s time. Our data show that following injection of the toxin conjugate, IB4-labelling, P2X3-immunopositive fibre terminals disappear from a band in the superficial dorsal horn that expands over a two week period until it comprises most of the mediolateral extent of the dorsal horn. Behavioural data indicates that there are transient changes in acute pain thresholds to mechanical and thermal stimuli. Changes in pain thresholds in animals lacking non-peptidergic input into the spinal dorsal horn in an animal model of Complete Freund’s Adjuvant (CFA) induced inflammation will also be presented.
Related Products: IB4-SAP (Cat. #IT-10)