Fig. 2

Hippocampal synapse reduction and increased NCAM/PSA-NCAM balance in VPA animals were established after the neonatal period. a VPA animals exhibited lower body weight at PND14, 23 and 35, worse swimming performance than controls at PND12 and 14 and reduced number of hole-poking and pinning at PND30-35. b Representative photomicrographs of CA3 hippocampal region from control and VPA animals immunostained for synaptophysin (SYN) at PND3 and 35. c Insets (4 × magnification) detail SYN immunostaining pattern. d SYN relative immunoreactive area quantification showed the absence of statistical differences at PND3 but a robust reduction at PND35. e Quantification of excitatory synapses (asymmetric) in the CA3 hippocampal region by electron microscopy depicted fewer synapses in VPA animals at PND35. f CA3 hippocampal region from control and VPA animals immunostained for PSA-NCAM at PND3 and 35. g VPA animals displayed conserved and reduced PSA-NCAM levels at PND3 and PND35, respectively. h CA3 hippocampal region from control and VPA animals immunostained for NCAM at PND3 and 35. i Quantification of NCAM relative immunoreactive area confirmed the absence of statistical differences at PND3 and an increase at PND35 in the VPA group. Results are expressed as mean values (± SD; a: control n = 6–8 animals, VPA n = 6–8 animals; n = 3 videos per group in the case of pinning assessment; d: control n = 4–6 animals, VPA n = 4 animals; e: control n = 3 animals, VPA n = 3 animals; g, i: control n = 4 animals, VPA n = 4 animals). ns: non-significant; *p < 0.05 between bars by Student’s t test; ^##p < 0.01; ^###p < 0.001 between groups by Mann–Whitney U Test. Scale bars: 50 µm (b, f, h); 100 nm (e). pyr: soma of CA3 pyramidal neurons