Article Figures & Data
Figures
- Figure 1.
mGlu2/3 receptor activation blocks PGE2-induced TRPV1 sensitization in mouse, but not human, sensory neurons. Representative traces of 100 nm capsaicin (Cap)-induced calcium responses in mouse (A) and human (B) DRG neurons in response to vehicle (left), 1 μm PGE2 (middle), or 1 μm PGE2 + 10 μm APDC (right). Experiments concluded with a pulse of 50 mm KCl to determine cell viability. The degree of TRPV1 sensitization is expressed as a response ratio calculated by dividing the peak amplitude of Cap 2 by the peak amplitude of Cap 1 (A, dashed lines). C, In mouse DRG neurons, PGE2 significantly increased the capsaicin response ratio compared with vehicle (**** p = 2.1 × 10–5; n = 143–150 neurons, n = 4 preps/condition). Coapplication of APDC with PGE2 blocked this effect and significantly reduced the response ratio compared to PGE2 alone (** p = 0.0081; n = 89–150 neurons, n = 3–4 preps/condition). D, PGE2 also significantly increased the capsaicin response ratio of human DRG neurons compared with vehicle (**** p = 3.0 × 10–6; n = 59–71 neurons, n = 5–6 donors/condition); whereas coapplication of APDC did not suppress PGE2-induced increases in the capsaicin response ratio (p = 1, n = 59–64 neurons, n = 6 donors/condition), which remained significantly greater than vehicle (** p = 0.0053, n = 64–71 neurons, n = 5–6 donors/condition). Capsaicin response ratios were compared using unpaired t tests and a Bonferroni correction for multiple comparisons. Data are presented as mean ± SEM. E, Compared with those of mice, a greater percentage of human DRG neurons responded to 100 nm capsaicin (χ2 = 15.45, **** p = 8.5 × 10–5, mouse: 405/1761 neurons, n = 4 preps, human: 223/731 neurons, n = 8 donors). F, LMM regression correction for impact of individual donor, as well as donor age and sex, did not alter human capsaicin response ratio analysis statistical outcomes compared with t tests alone.
- Figure 2.
Expression of Trpv1, Grm2, and Grm3 mRNA transcripts in dissociated mouse and human sensory neurons. A, Size distribution of total and Trpv1 + mouse DRG neuron populations; mean diameter of total neurons: 17.7 ± 0.2 μm (n = 395 neurons, n = 4 preps), mean diameter of Trpv1+ neurons: 20.3 ± 0.4 μm (n = 147 neurons). B, Size distribution of total and TRPV1+ human DRG neuron populations; mean diameter of total neurons: 31.9 ± 0.5 μm (n = 258 neurons, n = 5 donors), mean diameter of TRPV1+ neurons: 33.9 ± 0.9 μm (n = 83 neurons). Data are reported as mean ± SEM. C, The mean diameter of total human DRG neurons was significantly larger than that of total mouse DRG neurons (unpaired t test, **** p = 1.0 × 10–14). Data are presented as mean ± SD. Percentage of total mouse (D) and human (E) DRG neurons that expressed Trpv1, Grm2, and Grm3, as well as the percentage of neurons that coexpressed one mRNA transcript with another. Pie charts showing the percentage of Trpv1 + mouse (F) and human (G) DRG neurons that coexpressed Grm2, Grm3, or both transcripts. No significant differences in gene transcript expression of total neurons or Trpv1 + neuron subpopulations were observed between species.
Tables
Donor Age, y Sex Race Cause of death Tissue uses 1 21 Male White Stroke Ca2+ imaging 2 55 Female White Stroke Ca2+ imaging, FISH 3 22 Male Black Anoxia Ca2+ imaging 4 44 Female White Stroke Ca2+ imaging 5 12 Female White Anoxia Ca2+ imaging, FISH 6 26 Male White Head trauma Ca2+ imaging, FISH 7 18 Female White Head trauma Ca2+ imaging, FISH 8 18 Male White Head trauma Ca2+ imaging, FISH y, year; FISH, fluorescent in situ hybridization.
Target Catalog no. Mm-Trpv1 313331 Mm-Grm2-C3 317831-C3 Mm-Grm3-C2 317821-C2 Positive Control Probe-Mm 320881 Hs-TRPV1 415381 Hs-GRM2-C3 589771-C3 Hs-GRM3-C2 500181-C2 Positive Control Probe-Hs 320861 Negative Control Probe 320871 Mm, mus musculus; Hs, homo sapiens; C2, channel 2; C3, channel 3.
Location Data Structure Type of Test Comparison 95% confidence interval a Non-normally distributed t test Vehicle vs. PGE2 –0.6862 to –0.2728 b Non-normally distributed t test PGE2 vs. PGE2 + APDC 0.1317 to 0.618 Non-normally distributed t test Vehicle vs. PGE2 + APDC –0.2736 to 0.06428 c Non-normally distributed t test Vehicle vs. PGE2 –0.5774 to –0.2563 d Non-normally distributed t test PGE2 vs. PGE2 + APDC –0.4204 to 0.2717 Non-normally distributed Vehicle vs. PGE2 + APDC –0.7953 to –0.1871 e Non-normally distributed Regression Vehicle vs. PGE2 vs. PGE2 + APDC –0.1178 to 0.1284 f Categorical Chi-squareda 0.5621 to 0.8235 g Mouse: non-normally distributed t test Mouse vs. human –15.17 to –13.08 Human: normally distributed h Categorical Chi-squareda 2.653 to 4.769 i Categorical Chi-squareda 1.846 to 3.855 j Categorical Chi-squareda 1.047 to 1.967 The D’Agnostino and Pearson normality test was performed, when applicable.
aOdds ratio confidence interval reported.
In this issue
