Figure 3.

Effects of GDNF on loss of TH⁺ and FG⁺ cells in the SN after 6-OHDA. Since no significant effect of vehicle treatment was observed at any time, time 0 represents the mean values for all vehicle treated animals sacrificed at 2, 4, and 8 wks. There was a significant loss of TH⁺ cells in the SN at 2, 4 and 8 wks post infusion in animals treated with only 6-OHDA when compared to vehicle treated animals depicted as time 0 (**p < 0.001). Infusion of GDNF did not prevent a 6-OHDA-induced loss of TH⁺ cells when assessed at 2 wks compared to vehicle treated animals (**p < 0.001). However, by 4 wks the number of TH⁺ cells in the animals given both GDNF and 6-OHDA was significantly higher than that at 2 wks (†p < 0.05), although it was still significantly lower than vehicle (*p < 0.05). By 8 wk, no significant loss of TH⁺ cells was observed in 6-OHDA-treated animals given GDNF when compared to vehicle treated animals. No significant loss of FG⁺ cells in the SN was observed at any time in animals given 6-OHDA and GDNF. All values are expressed average number of cells ± S.E.M.