Systemic Candesartan Treatment Modulates Behavior, Synaptic Protein Levels, and Neuroinflammation in Female Mice That Express Human APOE4

Figures

• 

  FIGURE 1. Female and male E4FAD− and E4FAD+ mice treated with high-dose candesartan had higher plasma levels of candesartan and lower blood pressure compared to vehicle. (A) Female and male E4FAD− and E4FAD+ mice treated with 10 mg/kg/day candesartan (high dose) had higher plasma drug levels than mice treated with vehicle (0 mg/kg/day) [Female E4FAD−: F(2, 6) = 13.38, p = 0.006. Female E4FAD+: F(2, 5) = 19.10, p = 0.0046. Male E4FAD−: F(2, 4) = 324.6, p < 0.0001. Male E4FAD+: F(2, 6) = 13.53, p = 0.006]. (B) Female and male E4FAD− and E4FAD+ mice treated with 10 mg/kg/day candesartan had lower mean arterial blood pressure at treatment endpoint compared to vehicle (Female E4FAD−: F(2, 19) = 6.54, p = 0.0069. Female E4FAD+: F(2, 22) = 11.95, p = 0.0003. Male E4FAD−: F(2, 20) = 14.04, p = 0.0002. Male E4FAD+: F(2, 24) = 4.56, p = 0.021). All data expressed as mean +/− SEM. *p < 0.05 by one-way ANOVA and Dunnet’s post-hoc analysis for candesartan dose compared to vehicle. See Supplementary Table 2 for details on n size and statistical comparisons.

• 

  FIGURE 2. High-dose candesartan treatment resulted in improved memory-relevant behavior and higher hippocampal presynaptic protein levels in female, but not male, E4FAD− and E4FAD+ mice. (A) In female E4FAD− and E4FAD+ mice treated with 10 mg/kg/day (high dose) candesartan, performance was greater in the novel object recognition test compared to vehicle (0 mg/kg/day) at treatment endpoint [Female E4FAD−: F(2, 25) = 15.29, p < 0.0001. Female E4FAD+: F(2, 42) = 14.64, p < 0.0001]. This effect was not seen in male E4FAD− and E4FAD+ mice treated with 10 mg/kg/day candesartan [Male E4FAD−: F(2, 23) = 1.51, p = 0.24. Male E4FAD+: F(2, 26) = 1.23, p = 0.31]. (B) Female E4FAD− and E4FAD+ mice treated with 10 mg/kg/day candesartan had higher hippocampal levels of synaptophysin [Female E4FAD−: t(17) = 2.65, p = 0.017. Female E4FAD+: t(19) = 2.89, p = 0.0092], SV2A [Female E4FAD−: t(15) = 2.33, p = 0.034. Female E4FAD+: t(17) = 2.83, p = 0.012], and SNAP25 [Female E4FAD−: t(17) = 1.45, p = 0.16. Female E4FAD+: t(20) = 3.03, p = 0.0067] compared to vehicle when assessed by western blot analysis. Male E4FAD− and E4FAD+ mice treated with 10 mg/kg/day candesartan did not have altered hippocampal levels…

• 

  FIGURE 3. High-dose candesartan treatment did not alter hippocampal angiotensin peptide and receptor levels compared to vehicle treatment in female and male E4FAD− and E4FAD+ mice. In female and male E4FAD− and E4FAD+ mice treated with 10 mg/kg/day candesartan (high dose), there were no differences in hippocampal levels of (A) angiotensin II when assessed by ELISA analysis [Female E4FAD−: t(18) = 0.15, p = 0.88. Female E4FAD+: t(17) = 1.85, p > 0.081. Male E4FAD−: t(8) = 2.23, p = 0.056. Male E4FAD+: t(8) = 1.53, p = 0.16] as well as (B) angiotensinogen, AT1 receptor, or AT2 receptor levels compared to vehicle when assessed by western blot analysis [Angiotensinogen: Female E4FAD−: t(17) = 1.30, p = 0.21. Female E4FAD+: t(22) = 0.81, p = 0.43. Male E4FAD−: t(10) = 0.27, p = 0.79. Male E4FAD+: t(9) = 1.19, p = 0.26. AT1: Female E4FAD−: t(18) = 1.00, p = 0.33. Female E4FAD+: t(21) = 0.09, p = 0.92. Male E4FAD−: t(10) = 2.28, p = 0.073. Male E4FAD+: t(9) = 1.44, p = 0.18. AT2: Female E4FAD−: t(18) = 1.00, p = 0.33. Female E4FAD+: t(22) = 0.21, p = 0.84. Male E4FAD−: t(10) = 1.04, p = 0.32. Male E4FAD+: t(9) = 1.45, p = 0.17]. In (B) quantification of each protein was normalized to GAPDH as a…

• 

  FIGURE 4. High-dose candesartan treatment resulted in lower hippocampal levels of neuroinflammatory markers compared to vehicle treatment in female E4FAD− and E4FAD+ mice. Female E4FAD− and E4FAD+ mice treated with 10 mg/kg/day (high dose) candesartan had a lower percentage of hippocampal area immunostained with (A) Iba1 [E4FAD−: t(16) = 6.76, p < 0.0001. E4FAD+: t(18) = 5.08, p < 0.0001] and (B) GFAP [E4FAD−: t(16) = 15.06, p < 0.0001. E4FAD+: t(18) = 2.44, p = 0.025] compared to vehicle (0 mg/kg/day) when assessed by quantitative IHC analysis. All data expressed as mean +/− SEM. *p < 0.05 by Student’s t-test. Scale bars = 100 μm. See Supplementary Table 2 for details on n sizes.

• 

  FIGURE 5. High-dose candesartan treatment did not alter makers of cerebrovascular dysfunction or levels of extracellular Aβ compared to vehicle treatment in female E4FAD− and E4FAD+ mice. In female E4FAD− and E4FAD+ mice treated with 10 mg/kg/day (high dose) candesartan there were no differences in hippocampal area immunostained with (A) CD31 [E4FAD−: t(16) = 0.28, p = 0.78. E4FAD+:t(18) = 0.003, p = 0.99], (B) fibrinogen [E4FAD−: t(15) = 0.47, p = 0.64. E4FAD+: t(14) = 0.23, p = 0.82], or (C) Aβ [MOAB2 antibody, t(18) = 0.74, p = 0.47] compared to vehicle when assessed by quantitative IHC analysis. All data expressed as mean +/− SEM. p > 0.05 by Student’s t-test. Scale bars = 100 μm. See Supplementary Table 2 for details on n sizes.