Effect of intracerebral infusion of a Fzd receptor antagonist in GFAP response within the SNpc. The response of glial fibrillary acidic protein (GFAP) was assessed by immunohistochemical (A-I) and western blot (L)analyses within the SN ipsilateral and contralateral to saline or Dkk1 infusion. A-I: Representative immunofluorescent images of dual staining with GFAP+ (red) and TH (green) in SN ipsilateral and contralateral to saline or Dkk1 infusion. In saline-infused SN, there was no significant difference between the ipsilateral (A) and contralateral (B) SN, whereas Dkk1 infusion induced a marked increase in astrocyte density within the ipsilateral Dkk1-infused SN, at 1 (not shown), 3 (C) and 7 (E) days post-infusion, compared to contralateral (compare with D, F). Note the increased density of hypertrophic GFAP+ astrocytes abundantly covering the ipsilateral SN of Dkk1- infused (see F and I), as compared to saline-infused SN (C), thereby indicating a time- and site-specific GFAP response to Dkk1 intranigral infusion. J:GFAP protein levels within the ipsi- and contralateral SN of saline and Dkk1-infused mice (n = 4/time-point) by western blot (wb), showing a marked up-regulation of GFAP in Dkk1-ipsi but not contralateral SN by 1 day post-infusion, and further increasing at 3 and 7 days post-Dkk1. By contrast, unilateral saline infusion within the right SN was without effect on GFAP protein levels. Data from the experimental bands were normalized to beta-actin, and values expressed as per cent (%) of intact uninjected controls. *p < 0.05 ipsilateral vs contralateral, within each respective group.