Differential Expression of Synaptophysin and Synaptoporin During Pre‐ and Postnatal Development of the Rat Hippocampal Network

Abstract

The closely related synaptic vesicle membrane proteins synaptophysin and synaptoporin are abundant in the hippocampal formation of the adult rat. But the prenatal hippocampal formation contains only synaptophysin, which is first detected at embryonic day 17 (E17) in perikarya and axons of the pyramidal neurons. At E21 synaptophysin immunoreactivity extends into the apical dendrites of these cells and in newly formed terminals contacting these dendrites. The transient presence of synaptophysin in axons and dendrites suggests a functional involvement of synaptophysin in fibre outgrowth of developing pyramidal neurons. Synaptoporin expression parallels the formation of dentate granule cell synaptic contacts with pyramidal neurons: the amount of hippocampal synaptoporin, determined in immunoblots and by synaptoporin immunostaining of developing mossy fibre terminals, increases during the first postnatal week. Moreover, in the adult, synaptoporin is found exclusively in the mossy fibre terminals present in the hilar region of the dentate gyrus and the regio inferior of the cornu ammonis. In contrast, synaptophysin is present in all synaptic fields of the hippocampal formation, including the mossy fibre terminals, where it colocalizes with synaptoporin in the same boutons. Our data indicate that granule neuron terminals differ from all other terminals of the hippocampal formation by the presence of both synaptoporin and synaptophysin. This difference, observed in the earliest synaptic contacts in the postnatal hippocampus and persisting into adult life, suggests distinct functions of synaptoporin in these nerve terminals.

NeuroD2 regulates the development of hippocampal mossy fiber synapses

“…MF synapses in vitro were defined as the co-localization of the MF specific pre-synaptic marker synaptoporin (SPO), the excitatory pre-synaptic marker vesicular glutamate transporter 1 (Vglut1) and the post-synaptic scaffolding molecule PSD95 (Figure 5A-H) [25,26]. Consistent with the morphological analysis in vivo , there was a highly significant reduction in the density of MF synapses on the large proximal dendrites of pyramidal shaped neurons in NeuroD2 null cultures compared to controls (Figure 5I).…”

Differential expression of neuronal calcium sensor‐1 in the developing chick retina

“…Brains and retinae, removed from the eyecup, were postfixed in the same fixative for 4 hours and placed in PBS (pH 7.4) overnight. Sections were cut on a vibratome and processed for preembedding staining using the avidin-biotin-complex technique (for further details, see Bergmann et al, 1993Bergmann et al, , 2000Grabs et al, 1994Grabs et al, , 1996Grabs et al, , 2000. Sections were postfixed with 1% OsO 4 , counterstained with 4% uranyl acetate and 0.2% lead citrate, and examined by using a Zeiss EM10 electron microscope.…”

“…For protein detection using the Western blot technique, samples of rat hippocampus and mouse neocortex, as well as samples from the chick retina, tectum, and hyperstriatum, were homogenized and processed according to standard protocols (for further details, see Grabs et al, 1994Grabs et al, , 1996Grabs et al, , 2000Bergmann et al, 1996Bergmann et al, , 1999. Lanes of equal amounts (10 g) of total protein were run on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gels under reducing conditions and transferred to nitrocellulose.…”

“…Frontal cryosections were cut at 10 m. For immunofluorescence, two affinity-purified rabbit polyclonal antibodies against rat/mouse frequenin (44162 and 44163; Werle et al, 2000;Weisz et al, 2000) and a mouse monoclonal antibody recognizing SV2 (Buckley and Kelly, 1985; DSHB, Iowa City, IA) were diluted 1:100/500 in goat serum dilution buffer (pH 7.4; 20 mM NaPO 4 , 15% normal goat serum, 450 mM NaCl, 0.3% Triton X-100). Antigen/ antibody complexes were visualized using CY2-or CY3-conjugated goat anti-rabbit or goat anti-mouse IgGs (for further details, see Grabs et al, 1994Grabs et al, , 2000Grosse et al, 1998Grosse et al, , 1999Bergmann et al, 1999Bergmann et al, , 2000.…”

Characterization of a Novel synGAP Isoform, synGAP-β

“…8 (insets in a and b). The distribution of synGAP-␤ and synaptophysin, a presynaptic marker (27), was compared by double immunofluorescent staining (Fig. 8c).…”