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Figure 1 | Molecular Pain

Figure 1

From: Increased methylation of the MOR gene proximal promoter in primary sensory neurons plays a crucial role in the decreased analgesic effect of opioids in neuropathic pain

Figure 1

Systemic, spinal and periphery morphine analgesia decreased in neuropathic mice. (A) Effects of 1 mg/kg s.c. morphine on TWL in sham-operated and neuropathic pain mice on days -1, 1, 3, 7 and 14 after surgery. Results are presented as TWL at 30 min after s.c. injection of morphine or vehicle. ## p<0.05 compared with Sham-Vehicle; *p<0.05 compared with CCI-Vehicle, n=8 in each group. (B, C) Time course of the effects of s.c. morphine in sham-operated and nerve-injured mice on day 7 after surgery. Results are presented as TWL in seconds, comparison of morphine analgesia by area under the curve (AUC). *p <0.05, **p <0.01 compared with Vehicle, n=8 in each group. (D-G) Dose–response curves of s.c. (D), i.c.v. (E), i.t. (F) and i.pl. (G) morphine in sham-operated and nerve-injured mice on day 7 following surgery. The data are presented as AUC analgesic. **p <0.01 compared with Sham, n=8 mice in each group. (H) Effects of ipsilateral i.pl. morphine on contralateral paw withdrawal latency. Morphine (30 or 100 nmol i.pl.) was injected into the ipsilateral paw, and the PWL was measured in both the ipsi- and contralateral paw at 10 min following injection. (I, K) Western blot shows that MOR protein were markedly decreased in the spinal cord (I) and DRG (K) on day 7 after nerve injury, while no MOR protein decrease was observed in sham-operated mice. (J, L) qRT-PCR shows that MOR mRNA was heavily decreased in DRG (L) on day 7 day after nerve ligation, while no MOR mRNA decrease was observed in the spinal cord (J) and sham-operated mice. The ratio of MOR/GAPDH in contralateral spinal cord or DRG sham mice was set at 1 for quantifications. **p <0.01 compared with corresponding contralateral side, n=4 in each group.

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