Markers for the Study of Diabetic Neuropathy

Widely Used and Frequently Published
Our Pain and Inflammation Research Antibodies have proven valuable for the study of neuropathic, nociceptive and inflammatory pain.

This recent publication is focused on Diabetic Neuropathy. José Eduardo Roa-Coria, Jorge Baruch Pineda-Farias, Paulino Barragán-Iglesias, Geovanna Nallely Quiñonez-Bastidas, Ángel Zúñiga-Romero, Juan Carlos Huerta-Cruz, Juan Gerardo Reyes-García, Francisco Javier Flores-Murrieta, Vinicio Granados-SotoView ORCID ID profile and Héctor Isaac Rocha-González (2019). Possible involvement of peripheral TRP channels in the hydrogen sulfide-induced hyperalgesia in diabetic rats. BMC Neuroscience 201920:1 https://doi.org/10.1186/s12868-018-0483-3.

The results show Hydrogen Sulfide (H₂S) catalyzes hyperalgesia in rats via TRP Channels. Our Substance P is used in the study.

Figure: Immunolocalization of cystathionin-β-synthase enzyme (CBS, red) with a–e neuronal nuclear antigen (NeuN)-, f–j substance P (SP)-, k–o isolectin B4 (IB4)- and p–t glial fibrillary acidic protein (GFAP)-positive dorsal root ganglion neurons of diabetic rats (green). a, f, k and p show a representative 16 µm-slice from dorsal root ganglia. b, g, l and q show a representative CBS staining with Cy3 from dorsal root neurons, whereas c, h, m and r show NeuN, SP, IB4 and GFAP representative staining with Cy2 in dorsal root neurons, respectively. d, i, n and s show the merged image from Cy3 and Cy2 signals, the overlapping between CBS and neuronal markers is shown in a yellow-orange color. e, j, o and t show a magnification of d, i, n and s, respectively.

The authors conclude that H2S leads to hyperalgesia in diabetic rats through activation of TRPV1, TRPA1 and TRPC channels and, subsequent intraepidermal fibers loss. CBS enzyme inhibitors or TRP-channel blockers could be useful for the treatment of painful diabetic neuropathy.

Tissue Acidosis and Inflammation Related Nociceptive Pain

Important Implications for Inflammatory Pain States

Inflammatory pain is often accompanied by a drop in pH (Acidosis). Here investigators hypothesized that modest drops in extracellular pH leading to calcium fluxes acts like a dynamic switch to rapidly mobilize trkA to the cell membrane surface of adult sensory neurons, which in turn serves to increase the sensitivity of these neurons to NGF. The findings reveal a cellular mechanism whereby even small changes in pH can rapidly shift sensitivity to a critical driver of the inflammatory pain state—NGF. They way they demonstrate this shift is quite ingenious: Geoffrey E. Bray, Zhengxin Ying, Landon D. Baillie, Ruiling Zhai, Sean J. Mulligan, and Valerie M.K. Verge. Extracellular pH and Neuronal Depolarization Serve as Dynamic Switches to Rapidly Mobilize trkA to the Membrane of Adult Sensory Neurons. The Journal of Neuroscience, 8 May 2013, 33(19):8202-8215; doi:10.1523/JNEUROSCI.4408-12.2013.

Images: NGF-responsive adult sensory neurons have a large cytoplasmic pool of high-affinity NGF receptors. Six micrometer cryostat sections of L5 DRG processed for high-affinity NGF binding (left) or trkA immunohistochemistry (right) reveal a large cytoplasmic pool of proteins that are able to bind 20 pm radio-iodinated NGF with high affinity or that are immunoreactive to trkA-selective antibodies. Scale bar, 20 μm.

Here're images showing the pH Related switch and rapid migration of TrkA to the membrane

Images: Acidic pH challenge rapidly mobilizes trkA to the membrane from internal stores. A, Bar graphs summarize relative changes in neuronal cell-surface trkA expression from three separate experiments (detected with immunofluorescence) over neurons exposed to control (pH 7.4) or acidic (pH 6.5) media for 30 min with or without exposure to Golgi collapsing compound BFA and as normalized to the mean signal intensity from the control pH group. Note: A significant increase is observed in the mean levels of trkA mobilized to the neuronal membranes of sensory neurons in response to acidosis when compared with the control pH, a response that is blocked with BFA treatment. B, Immunofluorescence photomicrographs and summary histograms (C) depict degree of FM 1–43FX-stained neuronal membrane internalization in response to conditions as indicated. Note: Significant membrane internalization was only observed in the NGF challenge control group and not in response to acidic pH challenge with or without BFA treatment. (Data normalized to the control pH of each experimental condition and pooled from three separate experiments; A, C, one-way ANOVA with post hoc Tukey's, **< 0.01; ***< 0.001). Scale bar, 20 μm.

The heightened level of trkA activation likely has ramifications on both short- and long-term sensitization processes as it regulates the activity and expression of a wide variety of receptors, ion channels, and signaling molecules (Mantyh et al., 2011). In the short term, it modulates the activity of receptors and ion channels. For example, NGF decreases the threshold of activation of the nociceptive transient receptor potential vanilloid 1 (TRPV1) receptors (Chuang et al., 2001), mediates TRPV1 trafficking to the membrane (Stein et al., 2006), increases purinergic receptor P2X3-mediated currents and Ca²⁺ transients (D'Arco et al., 2007) and for sympathetic neurons, rapidly modulates the activity of at least four voltage-gated currents (Luther and Birren, 2009). In the long term, increased NGF can lead to increased transcription of many nociception-associated genes such as its receptors trkA and p75 (Verge et al., 1989, 1992); the neuropeptides Substance P, calcitonin gene-related peptide (Lindsay and Harmar, 1989; Verge et al., 1995), and PACAP; Jongsma Wallin et al., 2001, 2003); sodium channels (Dib-Hajj et al., 1998; Fjell et al., 1999; Kerr et al., 2001); and P2X3 (Ramer et al., 2001; Simonetti et al., 2006). It is also interesting to note that activation of trkA was linked in our study to a parallel activation of p38MAPK, which has been shown to be linked to NGF-mediated increases in ASIC3 expression during inflammation (Mamet et al., 2003).

Related Reagents:
All Trk Antibodies
Neurotrophin Antibodies
Neurotrophin Proteins
Primary Neurons and Astrocytes-Primary human, rat and mouse neurons and astrocytes by Category