Figure 4.

Effects of clodronate liposomes on the infiltration of macrophages and neutrophils and mechanical hypersensitivity in a mouse model of postoperative pain. Clodronate (100 µL/mouse) or control liposomes were intravenously administered to mice 1 h before the plantar incision surgery. (a) Representative photographs for immunofluorescence staining of Iba1 (green) and Gr1 (red) in the contralateral and ipsilateral hind paws one and three days after the surgery. Scale bar = 100 µm. White dashed line marks the outer of epidermis. White dotted lines separate the dermis from the epidermis and deeper layer. Graphs show Iba1 fluorescence intensity (b, n = 4–11) and the number of Gr1⁺ cells (c, n = 3–8) in vehicle- and clodronate-treated groups. Data are expressed as means ± S.E.M. *P < 0.05, ***P < 0.001. (d) To assess mechanical sensitivities in the ipsilateral hind paws of the vehicle- (n = 9) or clodronate-treated group (n = 11), the frequency of paw withdrawal responses to von Frey filament stimulation was measured before the surgery (pre) and one and three days after the surgery. Data are expressed as means of the percentage ± S.E.M. *P < 0.05, **P < 0.01, *** P < 0.001, compared with pre in each group. n.s.: not significant.