Fig. 9

Western blotting of glucose-regulated protein 78 (GRP78), glucose-regulated protein 94 (GRP94), activating transcription factor 4 (ATF4), activating transcription factor 6 (ATF6), Xbox binding protein 1 (XBP1), and phosphorylated inositol requiring kinase 1 (P-IRE-1) in the substantia nigra (a) and frontal cortex area 8 (b) shows significantly increased expression of ATF4 and ATF6 90 kDa at stages 5–6 (p < 0.05), and reduced expression of GRP94 at stages 3–4 and 5–6 (p < 0.01) in the substantia nigra in PD when compared with MA individuals. ATF6f (50 kDa), the cleaved and active form of ATF6, was not identified in any group. In contrast, significant reduction of GRP78 (p < 0.01 at stages 3–4, and p < 0.001 at stages 5–6) with preservation of other reticulum stress markers was found in frontal cortex area 8 in PD. Note that a double band with GRP94, ATF4, and P-IRE-1 antibodies is observed in the substantia nigra but not in the frontal cortex. The expected molecular weight is marked by an arrowhead in SN western blots. β-actin is used as a control of protein loading. AU: arbitrary units; *p < 0.05; **p <0.01