Somatostatin Receptor 1/5 Knockout and R6/2 Mice Figure 1. Representative low- and high-magnification photomicrogrpahs depicting comparative distribution of DARPP-32 immunoreactivity in striatum of R6/2 and SSTR1/52/2 mice. DARPP-32 like immunoreactivity was lost in striatum of R6/2 and SSTR1/52/2 mice, respectively (a). Comparable decreased expression of DARPP-32 (32 kDa) in R6/2 and SSTR1/52/2 mice was also seen in Western blot analysis (b). Calbindin like immunoreactivity was found to be increased in both R6/2 and SSTR1/52/2 mice compared to respective wt mice (c upper panel). Increased calbindin (28 kDa) expression was further confirmed with Western blot analysis (c bottom panel). Data presented as mean 6 SD for Western blot analysis (SSTR1/52/2, n = 5 and R6/2 mice, n = 3) in comparison to wt mice brain,***P,0.001 and *P,0.05. Scale bar = 150 mm and 20 mm upper and bottom panel a, 20 mm panel c and 5 mm for inset. doi:10.1371/journal.pone.0024467.g001 whether R6/2 and SSTR1/52/2 mice exhibit comparable cellular distribution pattern in NMDAR subunits and determined the expression levels of NR1, NR2A and NR2B using immunohisto- chemistry and Western blot analysis. As shown in Figure 3a, in wt mice brain NR1-like immunoreactivity in striatal neurons was confined to the cell membranes, as well as, intracellularly. Additionally, NR1-like immunoreactivity was also seen in nerve fibers. In comparison to wt, R6/2 mice brain displayed strong NR1 immunoreactivity that was restricted to cell membrane. Consistent with immunohistochemistry, increased receptor expression was observed in striatal tissue lysate prepared from R6/2 mice in comparison to wt. Similar pattern of NR-1 immunoreactivity was observed in SSTR1/52/2 mice in comparison to wt using immunohistochemistry and Western blot analysis (Figure 3a). Similar to the NR1 expression, NR2A subunit expression was increased in R6/2 and SSTR1/52/2 mice when compared to respective wt (Figure 3b). Interestingly, NR2A immunoreactivity expressed at cell surface in R6/2 mice in comparison to SSTR1/ 52/2 mice where receptor immunoreactivity was markedly intracellular. Western blot analysis revealed enhanced NR2A expression in SSTR1/52/2 mice in comparison to R6/2 mice as well as respective wt. In comparison to NR1 or NR2A expression, R6/2 and SSTR1/52/2 mice exhibited the loss of NR2B immunoreactivity. The loss of NR2B was to a greater extent in R6/2 brain than SSTR1/52/2 mice (Figure 3c). The distributional pattern of NR2B-like immunoreactivity was significantly different in PLoS ONE | www.plosone.org 3 September 2011 | Volume 6 | Issue 9 | e24467