Figure 4From: Acute morphine induces matrix metalloproteinase-9 up-regulation in primary sensory neurons to mask opioid-induced analgesia in mice Actue morphine treatment does not change the sizes of MMP-9- and MOR-positive neurons in DRGs. (A, B) Size frequency distribution (percentage) of MMP-9-positive neurons (A) and MOR-positive neurons (B) in DRGs 2 h after subcutaneous saline and morphine. 300-500 neurons from 3 animals were plotted in each group. Note that MMP-9 and MOR are mainly expressed in small- and medium-sized neurons.Back to article page