Fig. 3: Kir4.1 expression is diminished in Fmr1 knockout hippocampus.

a Representative examples of immunofluorescent labeling of Kir4.1 (red) and astrocyte marker glial fibrillary acidic protein (GFAP, green) in WT (dark blue) and Fmr1 KO (magenta) hippocampus. Scale bar: 50 µm. b Quantification of Kir4.1 integrated density (P = 0.018, U = 171) and c Kir4.1/ GFAP integrated density ratio (P = 0.010, U = 161) reveals decreased expression in Fmr1 KO stratum radiatum (n = 26 images from 6 mice) as compared to WT (n = 22 images from 5 mice). d Representative high magnification confocal images of a single astrocyte in CA1 stratum radiatum labeled by GFAP (green) and Kir4.1 (red) in WT and Fmr1 KO mice. Distribution of Kir4.1 puncta was determined at any radial position within 25 µm diameter (white arrow) starting from soma center (white point). Scale bar: 10 µm. e Kir4.1 radial intensity profile is similar in Fmr1 KO (n = 29 astrocytes from 5 mice) and WT (n = 23 astrocytes from 6 mice) astrocytes, but displays significant shift (P < 0.001, F(1, 3892) = 147.1) toward lower Kir4.1 intensity in Fmr1 KO when compared to WT astrocytes. f Examples of western blots showing surface expression of Kir4.1 in WT and Fmr1 KO hippocampi. Actin was used as a loading control. g Decreased level of surface Kir4.1 amount in Fmr1 KO (n = 3 mice; P = 0.030, t = 3.314, df = 4) as compared to WT hippocampus (n = 3 mice). Data are presented as mean values ± SEM (b, c, e, g). *P < 0.05, ***P < 0.001. Statistical significance was assessed by performing two-sided Mann–Whitney test (b, c), two-way ANOVA, post hoc Fisher LSD test (e) or two-sided unpaired Student’s t test (g). Arb. units: arbitrary units. Source data are provided as a Source Data file.