Fig. (5) Mu-Opioid (µ-OR) Receptor Immunostaining: PAG: (left) Representative images of µ-OR immunohistochemical images for sham
(A) and NP-treated (B) 4 weeks after surgery (dark spots represent positive staining; arrows indicate representative positive staining; scale
bar = 100 µm). Increased expression was observed in both sham (*p<0.0001) and NP-treated (*p<0.0001) animals at 1 week after surgery.
Expression levels of µ-OR in sham animals remained constant while expression levels of NP-treated animals continued to increase at 4
weeks (**p<0.0001 vs 4 week sham animals). RN: Expression level of µ-OR in the RN did not vary in sham or NP-treated animals. Data are
presented as mean ± standard deviation.