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Figure 6 | Molecular Pain

Figure 6

From: Acute morphine induces matrix metalloproteinase-9 up-regulation in primary sensory neurons to mask opioid-induced analgesia in mice

Figure 6

MMP-9 deficiency or inhibition causes enhanced opioid analgesia after subcutaneous injection of morphine and DAMGO. (A) Morphine (10 mg/kg, s.c) analgesia, as measured by tail flick latency, in wild-type and Mmp9-KO mice. *P < 0.05, compared to wild-type control, Student's t-test, n = 7. (B, C) Morphine (10 mg/kg, s.c) analgesia in wild-type mice after intrathecal injection of TIMP-1 (0.2 μg, B) and MMP-9 inhibitor-I (0.2 μg, C). *P < 0.05, compared to vehicle (10% DMSO or saline), Student's t-test, n = 7-10 mice. (D) DAMGO (10 mg/kg, s.c) analgesia in wild-type mice after intrathecal injection of MMP-9 inhibitor-I (0.2 μg) or vehicle (10% DMSO). *P < 0.05, compared to vehicle, Student's t-test, n = 9 mice. (E) Analgesia induced by low dose morphine (5 mg/kg, s.c) in wild-type and Mmp9-KO mice. *P < 0.05, compared to Wild-type control. Student's t-test, n = 5 mice. BL, baseline. Note that opioid analgesia by subcutaneous morphine or DAMGO is potentiated and prolonged in Mmp9-KOmice and after pharmacological inhibition of MMP-9.

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