Figure 2
(A) Tyrosine hydroxylase positive (TH+) cell counts in the substantia nigra (SN). (B) Animals received, into the SN, saline (SAL) and 12 days later received an intra-striatal injection of SAL. (C) Animals received lipopolysaccharide (LPS) into the SN and 12 days later received an intra-striatal injection of SAL. (D) Animals received SAL into the SN and 12 days later received an intra-striatal injection of 6-OHDA (5.0 μg). (E) Animals received LPS into the SN and 12 days later received an intra-striatal injection of 6-OHDA (5.0 μg). (F) Animals received an intra-striatal injection of 6-OHDA (5.0 μg) and 12 days later received LPS into the SN. (G) Animals received an intra-striatal injection of 6-OHDA-h (high) (22.5 μg). Letters inside bars of panel A represent respective images in panels below. 21 days was allowed following 6-OHDA injection in all conditions. There was an overall main effect across groups (ANOVA, p < 0.001). LPS injection into the SN was non-toxic to TH+ neurons (B vs. C, NS). LPS injection prior to 6-OHDA administration increased the amount of TH+ cell loss compared to SAL prior to 6-OHDA (D vs. E, *p < 0.05, post-hoc Holm-Sidak). Intra-striatal injection of 6-OHDA followed by injection of LPS in the SN produced no greater cell loss (D vs. F, NS). The high dose of 6-OHDA produced cell loss that was not significantly different from a low dose of 6-OHDA with prior exposure to LPS (E vs. G, NS), however the high dose of 6-OHDA was significantly greater than other conditions receiving the lower dose of 6-OHDA (G vs. D and F, # p < 0.05, post-hoc Holm-Sidak). 1st, first injection; 2nd, second injection; SNpc, pars compacta; SNpr, pars reticulata; VTA, ventral tegmental area; CP, cerebral peduncle; scale bar, 1.0 mm; magnification, 2.5×. Error bars, ± SEM; n = 6 per condition.