Neuropathic pain in a Fabry disease rat model
James J. Miller, Kazuhiro Aoki, Francie Moehring, Carly A. Murphy, Crystal L. O’Hara, Michael Tiemeyer, Cheryl L. Stucky, Nancy M. Dahms
James J. Miller, Kazuhiro Aoki, Francie Moehring, Carly A. Murphy, Crystal L. O’Hara, Michael Tiemeyer, Cheryl L. Stucky, Nancy M. Dahms
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Research Article Neuroscience

Neuropathic pain in a Fabry disease rat model

Abstract

Fabry disease, the most common lysosomal storage disease, affects multiple organs and results in a shortened life span. This disease is caused by a deficiency of the lysosomal enzyme α-galactosidase A, which leads to glycosphingolipid accumulation in many cell types. Neuropathic pain is an early and severely debilitating symptom in patients with Fabry disease, but the cellular and molecular mechanisms that cause the pain are unknown. We generated a rat model of Fabry disease, the first nonmouse model to our knowledge. Fabry rats had substantial serum and tissue accumulation of α-galactosyl glycosphingolipids and had pronounced mechanical pain behavior. Additionally, Fabry rat dorsal root ganglia displayed global N-glycan alterations, sensory neurons were laden with inclusions, and sensory neuron somata exhibited prominent sensitization to mechanical force. We found that the cation channel transient receptor potential ankyrin 1 (TRPA1) is sensitized in Fabry rat sensory neurons and that TRPA1 antagonism reversed the behavioral mechanical sensitization. This study points toward TRPA1 as a potentially novel target to treat the pain experienced by patients with Fabry disease.

Authors

James J. Miller, Kazuhiro Aoki, Francie Moehring, Carly A. Murphy, Crystal L. O’Hara, Michael Tiemeyer, Cheryl L. Stucky, Nancy M. Dahms

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Figure 9

Fabry rat sensory neurons exhibit larger mechanically activated currents than WT.

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Fabry rat sensory neurons exhibit larger mechanically activated currents...
(A) Cultured primary sensory neurons were patched, and a stimulating pipette was used to poke the neuron cell membrane. Below the schematic are example current traces from 1 WT (black) and 1 KO (red) neuron, both indented 5.04 μm. (B) Patched WT and KO neurons were indented with the stimulating pipette in increasing distances (0.84–6.72 μm), and the resulting current density (current normalized to cell capacitance) was recorded. The total respective number of WT and KO neurons patched: 38 and 44 (0.84 μm); 38 and 44 (1.68 μm); 38 and 42 (2.46 μm); 35 and 34 (3.28 μm); 31 and 22 (4.20 μm); 23 and 17 (5.04 μm); 13 and 14 (5.88 μm); and 8 and 5 (6.72 μm). Two-way ANOVA with Bonferroni post hoc analysis was performed. (C) The indentation required to elicit the first mechanical current is plotted. WT and KO mechanical threshold medians were compared using a Mann-Whitney test. (D) Neuron capacitance is plotted and means were compared with an unpaired, 2-tailed t test. (E) Example traces showing the different type of inward currents observed in sensory neurons. (F) Current profiles are shown for WT and KO neurons and were compared with a χ2 test. (G) For whole cell patch clamping, the goal is to first form a giga-ohm (GΩ) seal between the cell and patch pipette before breaking into the cell. Neuron fragility was judged on whether the patch pipette automatically broke into the cell rather than first forming the GΩ seal. Data were compared with χ2 and Fisher’s exact tests. (H) Resting membrane potentials are plotted for both WT and KO neurons, and means were compared with an unpaired, 2-tailed t test. (I) Rheobase, which is the amount of current required to elicit the first action potential, is plotted for both WT and KO and were compared with a Mann-Whitney test. B, D, and H show mean ± SEM. Sensory neurons were cultured from 3 WT and 3 KO rats ranging from 19–21 weeks of age. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001