Transganglionic labelling of primary sensory afferents in the rat lumbar spinal cord: comparison between wheatgerm agglutinin and the I-B4 isolectin fromBandeiraea simplicifolia

Abstract

We recently reported that the I-B4 isolectin from Bandeiraea simplicifolia could be used as a transganglionic neuronal tracer which appears to be selective for unmyelinated cutaneous afferents (C fibres) and their terminals in the superficial dorsal horn. As terminals in the superficial dorsal horn are also labelled by wheatgerm agglutinin, we sought to compare these two neuronal tracers. Three days after the injection of 1% wheatgerm agglutinin-HRP or 1% BSI-B4-HRP into the sciatic nerve of adult rats the lumbar spinal cord was processed for HRP reactivity. The majority of labelled structures was found in the superficial dorsal horn, with fewer labelled structures seen in the overlying white matter (including Lissauer's tract). In wheatgerm agglutinin-HRP experiments most labelled structures were synaptic terminals (63%) and unmyelinated axons (32%). About 3% of wheatgerm agglutinin-HRP-labelled structures were fine myelinated fibres (which were found only in lamina I and outer lamina II) and about 2% of label was located in neuronal somata. In contrast, label from BSI-B4-HRP experiments was found only in synaptic terminals (37%) and unmyelinated axons (63%). Previous studies have shown that small diameter dorsal root ganglion neurons and their terminals in the superficial dorsal horn express a range of structurally related carbohydrates that contain binding sites for BSI-B4 or wheatgerm agglutinin or both. Comparison of the labelling patterns produced by the two transganglionic tracers in the present study suggests that unmyelinated sciatic afferents express wheatgerm agglutinin and BSI-B4 binding sites, but some thin myelinated afferents, and a distinct form of synaptic terminal in lamina I/II outer, express the wheatgerm agglutinin binding site and not the BSI-B4 binding site.

Analysis of the distribution of binding sites for the plant lectin Bandeiraea simplicifolia I‐isolectin B4 on primary sensory neurones in seven mammalian species

“…The results of this study confirm previous reports of BSI-B 4 binding in the rat, mouse, and rabbit (Streit et al, 1985;Kruger, 1988, 1990;Plenderleith et al, 1992;Plenderleith and Snow, 1993;Kitchener et al, 1994;Wang et al, 1994), and are entirely consistent with studies reporting BSI-B 4 binding in dorsal root ganglia and spinal cord of the chicken (Scott et al, 1990), echidna (Ashwell and Zhang, 1997), opossum (Knott et al, 1999), and rhesus monkey (Tong et al, 1999). Furthermore, recent studies have reported BSI-B 4 binding sites on human primary sensory neurones collected either post-mortem or from patients undergoing surgery (Yiangou et al, 2000;Alavi et al, 2001).…”

“…The termination pattern of BSI-B 4 binding primary sensory neurones in the spinal cord correlates closely with that of cutaneous nociceptors (Light and Perl, 1979;Sugiura et al, 1986;Kitchener et al, 1994). Furthermore, the vast majority of BSI-B 4 -labelled neurones also express the vanilloid receptor subtype 1, a molecule widely implicated in transduction of nociceptive stimuli (Guo et al, 1999;Michael and Priestly, 1999).…”

Localization of P2X2 and P2X3 receptors in rat trigeminal ganglion neurons

“…In addition, we found that 64 % of P2X 3 receptor-expressing trigeminal ganglion neurons also express IB4, suggesting that they are mainly non-peptidergic, unmyelinated afferents, since IB4 labelling is almost entirely limited to non-peptide unmyelinated afferents in the rat (Ambalavanar and Morris, 1993;Kitchener et al, 1993;Kitchener et al, 1994;Stucky and Lewin, 1999;Gerke and Plenderleith, 2001). This proportion is in agreement with previous reports in the rat (73 %, Ambalavanar et al, 2005) and mouse (70 %, Ruan et al, 2004) trigeminal ganglia, but contrasts with studies in the DRG where almost all P2X 3 -expressing neurons are IB4-positive in the mouse (99 %, Ruan et al, 2004), rat (>94 %, Bradbury et al, 1998;Vulchanova et al, 1998;Novakovic et al, 1999) and cat (88 %, Ruan et al, 2005).…”

Removing TRPV1-expressing primary afferent neurons potentiates the spinal analgesic effect of δ-opioid agonists on mechano-nociception

“…To determine the effect of RTX treatment on the δ-opioid receptors and Griffonia simplicifolia isolectin B 4 (IB 4 )-positive DRG neurons and primary afferent terminals in the spinal dorsal horn, double fluorescence labeling of δ-opioid receptors and IB 4 [a marker for unmyelinated primary neurons and afferent fibers (Kitchener et al, 1994;Kitchener et al, 1993)] was performed in the lumbar DRGs and spinal cords from three RTX-treated and three vehicle-treated rats 4 weeks after treatment. As described previously (Chen and Pan, 2006b;Chen et al, 2007b), each rat was intracardially perfused with 4% paraformaldehyde and 10% sucrose in 0.1 M PBS (pH 7.4) while under deep anesthesia with pentobarbital sodium (60 mg/ kg, i.p.).…”