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. 2022 Sep 26;119(40):e2204828119. doi: 10.1073/pnas.2204828119

Fig. 4.

Fig. 4.

G protein–biased GPR3 AD mice display reduced Aβ pathology and increased microglial and astrocytic activation. (A) AD KI mice were crossed with the HA (AD KI;HA) and HA-Ala (AD KI;HA-Ala) mice. (B and C) TBS-soluble Aβ40 and Aβ42 are reduced in cortex and hippocampus of AD KI;HA-Ala mice relative to AD KI;HA mice at 6 mo of age (n = 12–16 male and female mice/genotype; Aβ40, P = 0.004; Aβ42, P = 0.013) (B) and hippocampus (Aβ40, P = 0.0004; Aβ42, P = 0.018) (C). (D) Aβ40 and Aβ42 levels are reduced in AD KI;HA-Ala relative to AD KI;HA neuronal cultures (n = 6 P0 mice/genotype; Aβ40, P = 0.0014; Aβ42, P = 0.0028). (E) Representative confocal immunofluorescence images show the cortex of AD KI;HA (Left Panel) and AD KI; HA-Ala (Right Panel) mice immunolabeled for Aβ plaques with an anti-APP antibody (6E10; white). (F) Aβ plaque area (in µm2) is reduced in AD KI;HA-Ala relative to AD KI;HA mice (P = 0.0027). (G) Amyloid plaque circularity index (scale of 0–1, with 1 being the most circular), as a measure of amyloid plaque compaction, indicates increased circularity of amyloid plaques in AD KI;HA-Ala relative to AD KI;HA mice (n = 6 male and female mice/genotype; P = 0.0027). (H) Representative confocal immunofluorescence images from the cortex indicate an increase in the percentage area occupied by IBA1+ cells in AD KI; HA-Ala (I) relative to AD KI;HA mice (n = 6 male and female mice/genotype). (J) Representative confocal immunofluorescence images show the cortex of AD KI;HA (Left Panel) and AD KI;HA-Ala (Right Panel) mice immunolabeled for microglia (IBA1; red) and Aβ plaques (6E10; green). (K) The amyloid plaque area covered by IBA1+ cells is increased in AD KI;HA-Ala relative to AD KI;HA mice. Data are presented as mean ± SEM, ns, not significant; *P < 0.05, **P < 0.01, and **P < 0.001 by unpaired Student’s t test. Scale bars = 10 µm. (L) Schematic diagram depicts the physiological and pathophysiological phenotypes of wild-type GPR3 and G protein–biased GPR3 mice in AD. Schematics (A and L) created with BioRender.com.