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. 2019 Apr 9;13:347. doi: 10.3389/fnins.2019.00347

FIGURE 1.

FIGURE 1

miR-873a-5p is upregulated, while A20 is downregulated in the spinal cord of morphine-tolerant (MT) mice. (A) Morphine-induced antinociception was assessed by the tail-flick test. Tail-flick latency was converted to MPE%. n = 8, ∗∗∗P < 0.001 compared with the NS group. (B) Real-time qPCR showed that miR-873a-5p expression increased in the morphine group 3, 5, and 7 days after chronic morphine administration, especially on day 7 compared to the expression in the control group. Data are expressed as the mean ± SD, n = 6 mice per group, ∗∗P < 0.01. (C) The staining of miR-873a-5p in the spinal cord, Scale bar = 100 μm. (D) Changes in the A20 protein expression level in the L4-L6 spinal cord were gradually decreased after the development of morphine tolerance, especially on day 7. n = 4 mice per group. Samples were collected on days 3, 5, and 7 following chronic morphine injection, ∗P < 0.05, ∗∗P < 0.01. (E) miR-873a-5p was assessed by in situ hybridization and staining of miR-873a-5p (red) with neurons (green, identified using NeuN), astrocytes (green, identified using GFAP) and microglia (green, identified using Iba1) of the spinal cord in morphine-tolerant mice. The data showed that miR-873a-5p was mainly expressed in neurons and astrocytes, whereas no expression was observed in microglia. Scale bar = 100 μm. Samples were collected on day 7 following chronic morphine injection.