Figure 6: Histamine and β-alanine activate different populations of DRG neurons. | Nature Communications

Figure 6: Histamine and β-alanine activate different populations of DRG neurons.

From: Three functionally distinct classes of C-fibre nociceptors in primates

Figure 6

(a) Specimen fluorescent picture of cultured DRG neurons investigated in calcium imaging studies. The intracellular calcium levels of the neurons numbered are shown in the traces in b. (Scale bar, 100 μm). (b) Traces of intracellular calcium responses from representative cells in a. Cells were tested with β-alanine (1 mM, 60 s), histamine (100 μM, 40 s) and capsaicin (5 μM) with at least a 3-min washout period between applications. Cells with an increase above 20% in the 340/380 ratio were classified as responders. Cell #1 and #2 are responsive to β-alanine but not histamine. In contrast, cell #3 is responsive to histamine but not β-alanine, whereas cell #4 only responds to capsaicin. (c) Venn diagram shows the incidence of response (percent) to different reagents. β-alanine responsive cells are separate from histamine-responsive cells. The majority of the β-alanine and histamine responsive cells also respond to capsaicin. A total of 484 cells from three monkeys were analysed: 8% responded to β-alanine, 9% to histamine and 27% to capsaicin. Less than 1% of the cells responded to both β-alanine and histamine, suggesting that β-alanine and histamine-responsive cells are separate subpopulations in DRG. Data are from cynomolgus monkeys only.

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