Microinjection of DHPG into the hippocampal CA1 in naïve rats induced dephosphorylation of FMRP (a, n = 6 rats in each group, Mann-Whitney U-statistic = 35.00, two-tailed P = 0.007), decreased the binding between phosphorylated FMRP (p-FMRP) and C1q mRNA (b, n = 6 rats in each group, Mann-Whitney U-statistic = 33.00, two-tailed P = 0.015), and increased C1q mRNA in the hippocampal CA1 synaptosome (c, n = 6 rats in each group, t = 2.8, DF = 10, two-tailed P = 0.018). DHPG also increased the C1q immunosignal co-localized with PSD95 in the hippocampal CA1 in the naïve rats (d, n = 5 rats in each group, t = 12.6, DF = 8, two-tailed P <0.0001, scale bar = 10 μm). Each dot represents the mean value of 4 brain sections of one rat. Data represent mean ± s.e.m. *P<0.05, **P<0.01, ***P<0.001.