Fig. 9

Increased M1 muscarinic receptor expression on activated microglia in the rat brain after long-term THP treatment. Portions of round-shaped cells are positive for CD68 (lysosomal membrane glycoprotein), indicating putative phagocytosis (a–c). The number of CD68 or M1-positive cells was stereologically quantified in the prefrontal cortex as a region of interest (d). Compared with NS-treated aging controls, stereological analysis revealed a significantly higher number of CD68 cells in THP-treated rats. There is also a tendency of increased M1 expression co-localized with CD68 on activated microglia in the rat cortex after long-term THP treatment (c, d). Scale bar = 50 μm (a, b); scale bar = 10 μm (c). ***P < 0.0001, compared with the NS-treated aging controls (Student’s t test)