Fig. (3) Metabotropic Glutamate Receptor 5 (mGluR5) Immunostaining: PAG: (left) Representative images of mGluR5 immunohistochemical images for sham (A) and NP-treated (B) 4 weeks after surgery (dark spots represent 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 compared to unoperated controls. At one week post surgery, mGluR5 expression levels was significantly different in NP-treated compared to sham (**p<0.0001). Expression levels of mGluR5 in sham animals returned to expression levels of pre-operative controls at 4 weeks while NP-treated (**p<0.0001) animals continued to have increased expression of mGluR5. RN: Expression level of mGluR5 in the red nucleus did not vary in sham or NP-treated animals. Data are presented as mean ± standard deviation.