Abstract

In the adult central nervous system, the expression of polysialylated forms of the cell-surface glycoprotein NCAM (PSA-NCAM) is thought to be confined to areas particularly susceptible to plastic changes. In the present study, PSA-NCAM was found to be expressed in the somata, dendrites and axonal processes of some neurons, including cartridge-like elements, which according to our criteria, were identified as chandelier cell axon terminals (chandelier terminals), in the adult human entorhinal cortex and neocortex. These chandelier terminals were very numerous in layers II and III, whereas in deeper layers they were found only occasionally. Double immunocytochemical staining for PSA-NCAM with parvalbumin (PV), with GABA transporter (GAT-1) or with the 5-HT1A serotonin receptor allowed us to verify them as true chandelier terminals. Nearly all (92–95%) PV-immunoreactive (-ir) and GAT-1-ir chandelier terminals in layers II and III coexpressed PSA-NCAM. Most of the PSA-NCAM-ir chandelier terminals (89–98%) were also labeled for PV and GAT-1. The results suggest that chandelier terminals in layers II and III of the human entorhinal cortex and temporal neocortex might be particularly susceptible to plastic changes.

Introduction

NCAM is a cell-surface glycoprotein of the immunoglobulin supergene family and is expressed in the brain as three main isoforms (180, 140 and 120 kDa) generated by the alternative splicing of a single gene on human chromosome 11 (Cunningham et al., 1987; Santoni et al., 1987; Goridis and Brunet, 1992). Polysialic acid (PSA) is a developmentally regulated carbohydrate composed of a linear homopolymer of α-2,8-linked sialic acid residues (Seki and Arai, 1993). NCAM undergoes post-translational modification during development, leading to the abundant addition of PSA chains on its extracellular domain — the fifth immunoglobulin-like domain of 180-NCAM (Rothbard et al., 1982; Finne et al., 1983; Finne and Makela, 1985; Seki and Arai, 1993). The presence of PSA in the NCAM molecule decreases adhesiveness, allowing structural changes to occur in neuronal membranes.

PSA-NCAM is highly expressed during development (late embryonic and early postnatal periods), when it is involved in neuronal migration, neurite extension, pathfinding and synapto-genesis (Sunshine et al., 1987; Doherty et al., 1990; Landmesser et al., 1990; Tang et al., 1992; Seki and Arai, 1993; Szele et al., 1994; Fields and Itoh, 1996). NCAM polysialylation exhibits an age-related decline and PSA-NCAM is progressively replaced, as development proceeds, by non-sialylated adult forms of NCAM that have increased adhesion properties and stabilize newly formed contacts (Edelman and Chuong, 1982; Hoffman et al., 1982; Rothbard et al., 1982; Finne et al., 1983; Sadoul et al., 1983; Rutishauser et al., 1988; Doherty et al., 1990; Chung et al., 1991; Troy, 1992; Fox et al., 1995; Fields and Itoh, 1996).

In the adult brain, PSA-NCAM expression is considerably reduced, although it has been shown to be highly expressed in certain areas (e.g. the olfactory bulb and hippocampus), where it is thought to negatively regulate cell–cell interactions, facilitating the occurrence of structural changes (Miragall et al., 1988; Aaron and Chesselet, 1989; Chung et al., 1991; Theodosis et al., 1991; Bonfanti et al., 1992; Seki and Arai, 1993; Miller et al., 1993; Muller et al., 1996; Cremer et al., 2000). In the adult human entorhinal cortex, previous workers (Mikkonen et al., 1998, 1999) have described the presence of 20–50 μm long PSA-NCAM-immunoreactive, vertically oriented processes in layers II and III that were described as ‘fiber bundles’. While examining human cortical tissue immunocytochemically stained for PSA-NCAM, we also observed the presence of such processes, which according to our criteria, were identified as chandelier cell axon terminals (chandelier terminals).

Chandelier cells are considered to be the most powerful GABAergic interneuron of the cerebral cortex, forming synapses exclusively with the axon initial segments of pyramidal cells (Szentágothai and Arbib, 1974; Fairén and Valverde, 1980; Peters et al., 1982; Somogyi et al., 1982, 1983a, Somogyi et al., b, 1985; Freund et al., 1983; DeFelipe et al., 1985). Chandelier terminals can be visualized using immunocytochemistry for the calcium-binding protein parvalbumin (PV) and the GABA transporter GAT-1 (DeFelipe, 1999). In addition, immunocytochemical staining for 5-HT1A can be used to label the axon initial segments of pyramidal cells (DeFelipe et al., 2001). Therefore, in the present study we have used double-labeling immunocytochemical techniques to verify the presence of PSA-NCAM immunolabeling in chandelier terminals in the adult human entorhinal cortex and temporal neocortex.

Materials and Methods

This work was carried out on sections of human post-mortem temporal cortex from three normal males. Two of them (aged 23 and 49 years) died in traffic accidents and the third case (aged 69 years) committed suicide. In all three cases, the brains were dissected out 2–3 h post-mortem and immersed in a solution of 4% paraformaldehyde in 0.1 M phosphate buffer (PB), pH 7.4, for 24–30 h at 4°C. Small blocks of 1.5 × 2 cm were taken from the entorhinal cortex — caudal and caudal-limiting fields (Insausti et al., 1995) — and from the middle and inferior temporal gyri (areas 20 and 21 of Brodmann).

After fixation, the blocks were cut serially at 50 or 100 μm with a Vibratome and the sections were pretreated with a solution of ethanol and hydrogen peroxidase in PB to remove endogenous peroxidase activity. Sections were then processed by immunoperoxidase or double-labeling immunoflurorescence techniques for light/fluorescent microscopy. All antisera and antibodies used were diluted in PB containing 3% normal serum of the species in which the secondary antibody was raised, 2% bovine serum albumin and 0.25% Triton X-100 (stock solution).

Single Immunoperoxidase Staining

Free-floating sections were preincubated for 1 h in stock solution and then incubated for 36–48 h at 4°C in stock solution containing mouse anti-PSA-NCAM (1:6000, IgM, 5A5; Developmental Studies Hybridoma Bank, IA), rabbit anti-PV (1:4000, Swant; Bellinzona, Switzerland), rabbit anti-GAT-1 (1:2000, Chemicon; Temecula, CA) or rabbit anti-5-HT1A (1:1500) (Azmitia et al., 1992). The monoclonal antibodies against PSA-NCAM that were used specifically recognize the polysialyglycan chain of NCAM. These antibodies were purified from hybridoma cells obtained by the fusion of NS1 cells and mice spleen cells immunized with membrane preparations from E14–E15 rat spinal cord (Dodd et al., 1988).

The sections were then processed by the avidin–biotin–peroxidase method, using secondary goat anti-mouse IgM or goat anti-rabbit biotinylated antibodies (1:200; Vector Laboratories, Burlingame, CA) and the Vectastain ABC immunoperoxidase kit (Vector). Sections were reacted histochemically with 0.05% 3,3′-diaminobenzidine tetrahydrochloride (DAB; Sigma, St Louis, MO) and 0.01% hydrogen peroxide. Finally, sections were mounted onto glass slides, dehydrated, cleared with xylene and coverslipped. Adjacent sections were stained with thionin to reveal laminar boundaries and regional borders of the temporal cortex.

Double Immunofluorescence Staining

Sections were double-stained for PSA-NCAM and PV, PSA-NCAM and GAT-1 or PSA-NCAM and 5-HT1A, using the same primary antibodies, dilutions and incubation times as indicated above. Sections were first incubated in a solution containing the primary antisera (anti-PV, anti-GAT-1 or anti-5-HT1A) and then incubated for 2 h at room temperature in goat anti-rabbit antibodies coupled to Alexa 594 (1:1000; Molecular Probes, Eugene, OR). After rinsing in PB, sections were incubated in a solution containing anti-PSA-NCAM antibodies and then incubated in biotinylated horse anti-mouse IgM antibodies (1:200; Vector). Thereafter, sections were incubated for 2 h at room temperature in streptoavidin coupled to Alexa fluor 488 (1:1000; Molecular Probes), washed and mounted in 50% glycerol in PB. Sections were examined in a Leica TCS 4D confocal laser scanning system attached to a Leitz DMRIB microscope and equipped with an argon/krypton mixed gas laser with excitation peaks at 489 nm (for Alexa 488-labeled profiles) and 649 nm (for Alexa 594-labeled profiles). The fluorescence of profiles labeled with each chromogen was recorded through separate channels. Z-sectioning was performed at 1.5–2 μm intervals, and optical stacks of four to seven images were used for figures.

For all immunocytochemical procedures, controls consisted of processing selected sections either after replacing the primary antibody with preimmune goat or horse serum, after omission of the secondary antibody, or after replacement of the secondary antibody with an inappropriate secondary antibody. No significant staining was detected under these control conditions.

To quantify the percentage of colocalization of PSA-NCAM and PV or PSA-NCAM and GAT-1 in chandelier terminals, counts of single- and double-labeled profiles were made in sections from the entorhinal cortex and neocortex of two humans. For each double-labeling combination and individual case, a total of 10 randomly selected microscopic fields (160 000 μm2 each) from layers II and III were used to estimate the percentage of colocalization.

Results

In none of the three cases analyzed in the present study was any obvious external or microscopic anatomical evidence of brain pathology found. In addition, similar patterns of PSA-NCAM, PV and 5-HT1A immunostaining of chandelier cell terminals were found in all cases, despite of differences in age or cause of death.

In both the entorhinal cortex and neocortex, PSA-NCAM immunocytochemistry revealed the presence of numerous immunoreactive (-ir) elements that include cell bodies, terminal- like puncta in the neuropil and surrounding unstained cell bodies (basket formations), dendritic processes, fibers and chandelier terminals (short, vertically-oriented rows of buttons; Figs 1–3). The morphology of chandelier terminals was clearly identified (DeFelipe et al., 1989) and distinguished from other immunoreactive elements. Furthermore, chandelier terminals were more intensely immunostained than other processes (Fig. 3). Since the general pattern of PSA-NCAM immunostaining has been described in the human cortex (Mikkonen et al., 1998, 1999), we will refer only to chandelier terminal-labeling unless otherwise specified.

PSA-NCAM-ir chandelier terminals ranged in length from 20 to 70 μm in the entorhinal cortex (mean length ± SD, 43 ± 12.64 μm; n = 30; Fig. 1A,B) and 20–40 μm in the neocortex (31 ± 3.83 μm; n = 30; Fig. 1E,F). The distribution of labeled chandelier terminals was not homogeneous through the cortical layers. In both the entorhinal cortex and neocortex, they were more abundant in layers II and III than in infragranular layers, where they were found only occasionally (Fig. 2). The highest intensity of PSA-NCAM immunostaining was observed in chandelier terminals in the entorhinal cortex, while in the neocortex they were, in general, less intensely labeled (Fig. 1). In the temporal neocortex, chandelier terminals were more numerous and evenly distributed in layer II and in the superficial portion of layer III than in deep layer III (Fig. 2). In the entorhinal cortex, PSA-NCAM-ir chandelier terminals in layer II were usually bent, randomly oriented (Figs 1 and 2) and mainly clustered in the round and elongated patches characteristic of this layer. In the entorhinal caudal-limiting field, layer II PSA-NCAM-ir processes were found associated mainly with clusters of small pyramidal cells — see Insausti et al. (Insausti et al., 1995) for cytoarchitectonic details. In layer III of the entorhinal cortex, PSA-NCAM-ir chandelier terminals appeared more scattered than in layer II, being vertically oriented and more densely distributed in the superficial than in deeper portions of this layer (Fig. 2).

PV and GAT-1 immunocytochemistry revealed the presence of chandelier terminals with density and distribution patterns similar to those of the PSA-NCAM-ir processes in layers II and III of the entorhinal cortex and temporal neocortex (Figs 1–3). Moreover, PV (Fig. 2) and GAT-1 immunostaining showed the presence of numerous chandelier terminals in layer VI of the entorhinal cortex and in layers IV–VI of the temporal neocortex.

In double-labeling experiments, high rates of colocalization of PSA-NCAM and PV, as well as PSA-NCAM and GAT-1 in chandelier terminals, were found in layers II and III of both cortical areas (Fig. 3, Table 1). Nearly all chandelier terminals labeled for PV or GAT-1 in the entorhinal cortex (95 and 94.5%, respectively) and in the neocortex (93 and 92%, respectively) coexpressed PSA-NCAM (Table 1). In addition, as shown in Table 1, most PSA-NCAM-ir chandelier terminals colocalized PV (Fig. 3AC) and GAT-1 (Fig. 3DF) in both cortical areas. Thus, PSA-NCAM immunocytochemistry labels a subpopulation of chandelier terminals, most of which coexpress PV and GAT-1.

In both the entorhinal cortex and neocortex, 5-HT1A receptor immunocytochemistry revealed the presence of vertically oriented labeled processes in layers II and III corresponding to the proximal portions of pyramidal cell axons (DeFelipe et al., 2001). In PSA-NCAM/5-HT1A double-labeled sections, PSA- NCAM-ir chandelier terminals were found surrounding 5-HT1A-ir pyramidal cell axons (Fig. 3GI).

Discussion

The main finding of the present study is that a selective, large subpopulation of chandelier terminals in layers II and III of the human entorhinal cortex (caudal and caudal-limiting fields) and temporal neocortex (areas 20 and 21 of Brodmann) express PSA-NCAM. Identical PSA-NCAM-ir processes were described as fiber bundles in previous studies in the human cortex (Mikkonen et al., 1998, 1999). However, the present colocalization study allowed us to conclude that these elements are chandelier terminals.

The expression of PSA-NCAM was not only confined to chandelier terminals. Other immunoreactive elements, such as terminal-like puncta, dendrites and fibers, were frequently found, although less intensely stained. These latter PSA-NCAM-ir elements have previously been described in the human cortex (Mikkonen et al., 1998, 1999). Thus, in the following sections we will only refer to chandelier terminals.

PSA-NCAM-ir Chandelier Terminals: Possible Functional Roles

The expression of PSA and NCAM in different brain regions has a fast turnover and is regulated by neuronal and synaptic activity (Landmesser et al., 1990; Theodosis et al., 1991; Doyle et al., 1992; Kiss et al., 1994; Muller et al., 1996; Kiss and Rougon, 1997; Nothias et al., 1997; Ronn et al., 2000). Interestingly, earlier workers (Mikkonen et al., 1998) found an increase in PSA-NCAM neuropil staining and a decrease in the number of fiber bundles in layer II of the entorhinal cortex of patients with temporal lobe epilepsy. According to the present data, this decrease might be related to the loss of chandelier terminals in temporal cortical regions found in epileptic patients (DeFelipe, 1999). We speculate that changes in chandelier cell activity, by up- or down-regulating the expression of PSA-NCAM, might promote structural and/or functional reorganization of the inhibitory synaptic input to pyramidal cells. Furthermore, a decrease in the number of supragranular GAT1-positive chandelier cell axon terminals has been reported in areas 9 and 46 of patients suffering schizophrenia (Lewis et al., 1999; Lewis, 2000). Thus, it will be interesting to know whether PSA-NCAM-ir chandelier terminals are affected or not in these patients.

The presence of PSA-NCAM in chandelier terminals suggests that this glycoprotein makes heterophilic contacts with a different adhesion molecule present in the pyramidal cell axon membrane. For example, adhesion proteins of the L1-CAM family, such as neurofascin and NrCAM, which play important roles as binding partners for NCAM, are concentrated at the axon initial segment and nodes of Ranvier in different neuronal types, where they are involved in the restriction of voltage-gated sodium channels to these locations (Davis et al., 1996; Hortsch, 1996; Brummendorf et al., 1998; Bennett and Lambert, 1999). It is, therefore, possible that PSA-NCAM from chandelier terminals interacts with L1-CAM adhesion proteins of the pyramidal cell axon initial segment. Further electron microscopy double-labeling immunogold studies are necessary to examine this possibility.

Based on what is known about cell adhesion molecules, PSA-NCAM in chandelier terminals might have the following functions. (i) The maintenance of a weak adhesion to the pyramidal cell axons they surround. This would confer a permissive environment for the structural remodeling of the contacts between axons of both cell types. (ii) PSA-NCAM might influence the physiological parameters of the axo-axonic synapses, since, in other cell types, PSA-NCAM affects second messenger systems and triggers intracellular signal transduction events (Schuch et al., 1989; Doherty et al., 1991; Doherty and Walsh, 1992, 1994; Muller et al., 2000). (iii) PSA-NCAM might be involved in synaptic plasticity, as expression of NCAM, PSA-NCAM and adhesion proteins of the L1 family are essential for the induction of activity-induced forms of physiological plasticity, such as LTP and LTD, in both excitatory and inhibitory synapses (Becker et al., 1996; Luthi et al., 1996; Muller et al., 1996; Cotman et al., 1998; Cremer et al., 2000). In addition, removing PSA from NCAM with endoneuraminidase-N impairs LTP in CA1 cells and impairs the acquisition and retention of spatial memory in rats (Becker et al., 1996; Muller et al., 1996; Ronn et al., 2000).

Therefore, chandelier cells may be important not only for the inhibitory control of pyramidal cell activity (DeFelipe, 1999), but also in activity-dependent plastic changes of pyramidal cells.

Functional Implications of the Laminar Distribution of PSA-NCAM-ir Chandelier Terminals

Chandelier terminals are present throughout layers II–VI of the human entorhinal cortex and neocortex (Fonseca et al., 1993; Schmidt et al., 1993; del Rio and DeFelipe, 1994), whereas those immunolabeled for PSA-NCAM were found mostly in layers II and III. The entorhinal cortex is part of the mesial temporal structures involved in the consolidation of declarative memory and plays a pivotal role in gating the flow of cortical information to the hippocampus (Amaral, 1993; Witter, 1993; Squire and Zola, 1996). Pyramidal cells located in layers II and III of the entorhinal cortex give rise to the main source of cortical input to the hippocampus through the perforant pathway (Amaral, 1993; Witter, 1993). The high expression of PSA-NCAM found in chandelier terminals in layers II–III of the entorhinal cortex suggests that the modulation of cortical input to the hippo-campus by chandelier cells is highly susceptible to plastic changes, a feature that could be particularly relevant to the process of memory consolidation. Similarly, pyramidal cells located in different layers of the neocortex project to different targets (Jones, 1984; White, 1989; Rockland, 1997). The projections arising from supragranular pyramidal cells participate in the control of temporal cortico-cortical networks involved in high-order associative processes. Thus, the selective expression of PSA-NCAM found in supragranular layers of the cortex suggests that the modulation of specific projection pathways, by PSA-NCAM-expressing chandelier cells, may be more susceptible to plastic changes than others. Whether alterations in behaviour associated with certain mental disorders such as schizophrenia are related to plastic alterations of specific projections as the result of changes in PSA-NCAM expression in chandelier cell axons is a possibility that should be explored in future studies.

Finally, the present results, together with previous studies showing laminar differences in the expression of 5-HT1A sero-tonin receptors (DeFelipe et al., 2001) and in the subunit composition of GABAA receptors (Fritschy et al., 1998) in the proximal portion of pyramidal cell axons, further support the existence of remarkable differences in the relationship between chandelier cells and pyramidal cells in supragranular versus infragranular layers.

Table 1

Percentages of colocalization (mean ± SD) of PSA-NCAM with either PV or GAT-1 in chandelier terminals from layers II–III of the entorhinal cortex and temporal neocortex

 Entorhinal cortex Neocortex 
The numbers of chandelier terminals immunoreactive for the first antibody of each combination are indicated in parentheses. 
PV/PSA-NCAM 95.05 ± 5.81 (296) 93.01 ± 7.02 (220) 
PSA-NCAM/PV 96.86 ± 5.22 (289) 95.73 ± 9.69 (214) 
GAT-1/PSA-NCAM 94.50 ± 6.24 (271) 92.31 ± 7.58 (234) 
PSA-NCAM/GAT-1 96.47 ± 5.22 (263) 89.24 ± 8.99 (242) 
 Entorhinal cortex Neocortex 
The numbers of chandelier terminals immunoreactive for the first antibody of each combination are indicated in parentheses. 
PV/PSA-NCAM 95.05 ± 5.81 (296) 93.01 ± 7.02 (220) 
PSA-NCAM/PV 96.86 ± 5.22 (289) 95.73 ± 9.69 (214) 
GAT-1/PSA-NCAM 94.50 ± 6.24 (271) 92.31 ± 7.58 (234) 
PSA-NCAM/GAT-1 96.47 ± 5.22 (263) 89.24 ± 8.99 (242) 
Figure 1.

(A–D) Low- (A, C) and high-magnification (B, D) images taken from sections through the outer layer III of the entorhinal cortex (male, 23 years old) immunostained for PSA-NCAM (A, B) or for PV (C, D). (E) and (F) show, respectively, low- and high-magnification images taken from sections in layers II–III of the temporal neocortex immunostained for PSA-NCAM. Arrows point to some immunostained chandelier axon terminals. Scale bars: 48 μm (A, C, E); 17 μm (B); 10 μm (D); 15 μm (F).

Figure 1.

(A–D) Low- (A, C) and high-magnification (B, D) images taken from sections through the outer layer III of the entorhinal cortex (male, 23 years old) immunostained for PSA-NCAM (A, B) or for PV (C, D). (E) and (F) show, respectively, low- and high-magnification images taken from sections in layers II–III of the temporal neocortex immunostained for PSA-NCAM. Arrows point to some immunostained chandelier axon terminals. Scale bars: 48 μm (A, C, E); 17 μm (B); 10 μm (D); 15 μm (F).

Figure 2.

Camera lucida drawings of PSA-NCAM-ir and PV-ir chandelier terminals in adjacent sections of the human (male, 23 years old) entorhinal cortex and temporal neocortex. Note, in both cortical regions, that PSA-NCAM-ir chandelier terminals are more abundant in layers II and III than in deeper layers. Scale bar: 200 μm.

Figure 2.

Camera lucida drawings of PSA-NCAM-ir and PV-ir chandelier terminals in adjacent sections of the human (male, 23 years old) entorhinal cortex and temporal neocortex. Note, in both cortical regions, that PSA-NCAM-ir chandelier terminals are more abundant in layers II and III than in deeper layers. Scale bar: 200 μm.

Figure 3.

Series of confocal images from the same section and field taken from layer III of the entorhinal cortex (male, 23 years old) to illustrate double labeling in chandelier terminals (arrows). PSA-NCAM-ir chandelier terminals are shown in green (A, D, G), while red images show PV-ir (B) and GAT-1-ir (E) chandelier terminals and a 5-HT1A-immunostained pyramidal cell axon (H). (C, F, I) were obtained after combining images (A, B), (D, E) and (G, H), respectively. Note that PV and GAT-1-ir chandelier terminals colocalize PSA-NCAM and surround 5-HT1A-ir pyramidal cell axons. In (A), arrowheads indicate some thinner processes, lightly stained for PSA-NCAM, which are not immunostained for PV (B). These processes are not chandelier terminals. In (B), arrowheads point to some PV-ir dendritic processes which do not coexpress PSA-NCAM (A). (AC) A stack of seven optical images separated by 1.57 μm in the z-axis (total, 9.4 μm). (DF) A stack of four optical images separated by 1.87 μm in the z-axis (total, 5.6 μm). (GI) A stack of five optical images separated by 1.56 μm in the z-axis (total, 6.2 μm). Scale bar: 14 μm (AC); 16 μm (DF); 12 μm (GI).

Figure 3.

Series of confocal images from the same section and field taken from layer III of the entorhinal cortex (male, 23 years old) to illustrate double labeling in chandelier terminals (arrows). PSA-NCAM-ir chandelier terminals are shown in green (A, D, G), while red images show PV-ir (B) and GAT-1-ir (E) chandelier terminals and a 5-HT1A-immunostained pyramidal cell axon (H). (C, F, I) were obtained after combining images (A, B), (D, E) and (G, H), respectively. Note that PV and GAT-1-ir chandelier terminals colocalize PSA-NCAM and surround 5-HT1A-ir pyramidal cell axons. In (A), arrowheads indicate some thinner processes, lightly stained for PSA-NCAM, which are not immunostained for PV (B). These processes are not chandelier terminals. In (B), arrowheads point to some PV-ir dendritic processes which do not coexpress PSA-NCAM (A). (AC) A stack of seven optical images separated by 1.57 μm in the z-axis (total, 9.4 μm). (DF) A stack of four optical images separated by 1.87 μm in the z-axis (total, 5.6 μm). (GI) A stack of five optical images separated by 1.56 μm in the z-axis (total, 6.2 μm). Scale bar: 14 μm (AC); 16 μm (DF); 12 μm (GI).

This work was supported by a DGCYT PM99-0105 grant and Comunidad de Madrid grant 0.8.5/0036/2000. We thank A. Ortiz for technical assistance and C. Hernández for assistance with the confocal microscope.

References

Aaron LI, Chesselet MF (
1989
) Heterogeneous distribution of polysialylated neuronal-cell adhesion molecule during post-natal development and in the adult: an immunohistochemical study in the rat brain.
Neuroscience
 
28
:
701
–710.
Amaral DG (
1993
) Emerging principles of intrinsic hippocampal organization.
Curr Opin Neurobiol
 
3
:
225
–229.
Azmitia EC, Yu I, Akbari HM, Kheck N, Whitaker-Azmitia PM, Marshak DR (
1992
) Antipeptide antibodies against the 5-HT1A receptor.
J Chem Neuroanat
 
5
:
289
–298.
Becker CG, Artola A, Gerardy-Schahn R, Becker T, Welzl H, Schachner M (
1996
) The polysialic acid modification of the neural cell adhesion molecule is involved in spatial learning and hippocampal long-term potentiation.
J Neurosci Res
 
45
:
143
–152.
Bennett V, Lambert S (
1999
) Physiological roles of axonal ankyrins in survival of premyelinated axons and localization of voltage-gated sodium channels.
J Neurocytol
 
28
:
303
–318.
Bonfanti L, Olive S, Poulain DA, Theodosis DT (
1992
) Mapping of the distribution of polysialylated neural cell adhesion molecule throughout the central nervous system of the adult rat: an immunohistochemical study.
Neuroscience
 
49
:
419
–436.
Brummendorf T, Kenwrick S, Rathjen FG (
1998
) Neural cell recognition molecule L1: from cell biology to human hereditary brain malformations.
Curr Opin Neurobiol
 
8
:
87
–97.
Chung WW, Lagenaur CF, Yan YM, Lund JS (
1991
) Developmental expression of neural cell adhesion molecules in the mouse neocortex and olfactory bulb.
J Comp Neurol
 
314
:
290
–305.
Cotman CW, Hailer NP, Pfister KK, Soltesz I, Schachner M (
1998
) Cell adhesion molecules in neural plasticity and pathology: similar mechanisms, distinct organizations?
Prog Neurobiol
 
55
:
659
–669.
Cremer H, Chazal G, Lledo PM, Rougon G, Montaron MF, Mayo W, Le Moal M, Abrous DN (
2000
) PSA-NCAM: an important regulator of hippocampal plasticity.
Int J Dev Neurosci
 
18
:
213
–220.
Cunningham BA, Hemperly JJ, Murray BA, Prediger EA, Brackenbury R, Edelman GM (
1987
) Neural cell adhesion molecule: structure, immunoglobulin-like domains, cell surface modulation, and alternative RNA splicing.
Science
 
236
:
799
–806.
Davis JQ, Lambert S, Bennett V (
1996
) Molecular composition of the node of Ranvier: identification of ankyrin-binding cell adhesion molecules neurofascin (mucin+/third FNIII domain–) and NrCAM at nodal axon segments.
J Cell Biol
 
135
:
1355
–1367.
DeFelipe J (
1999
) Chandelier cells and epilepsy.
Brain
 
122
:
1807
–1822.
DeFelipe J, Fairén A (
1993
) A simple and reliable method for correlative light and electron microscopic studies.
J Histochem Cytochem
 
41
:
769
–772.
DeFelipe J, Hendry SH, Jones EG, Schmechel D (
1985
) Variability in the terminations of GABAergic chandelier cell axons on initial segments of pyramidal cell axons in the monkey sensory-motor cortex.
J Comp Neurol
 
231
:
364
–384.
DeFelipe J, Hendry SHC, Jones EG (
1989
) Visualization of chandelier cell axons by parvalbumin immunoreactivity in monkey cerebral cortex.
Proc Natl Acad Sci USA
 
86
:
2093
–2097.
DeFelipe J, Arellano JI, Gomez A, Azmitia EC, Muñoz A (
2001
) Pyramidal cell axons show a local specialization for GABA and 5-HT inputs in monkey and human cerebral cortex.
J Comp Neurol
 
433
:
148
–155.
Del Rio MR, DeFelipe J (
1994
) A study of SMI 32-stained pyramidal cells, parvalbumin-immunoreactive chandelier cells, and presumptive thalamocortical axons in the human temporal neocortex.
J Comp Neurol
 
342
:
389
–408.
Dodd J, Morton SB, Karagogeos D, Yamamoto M, Jessell TM (
1988
) Spatial regulation of anonal glycoprotein expression on subsets of embryonic spinal neurons.
Neuron
 
1
:
105
–116.
Doherty P, Walsh FS (
1992
) Cell adhesion molecules, second messengers and axonal growth.
Curr Opin Neurobiol
 
2
:
595
–601.
Doherty P, Walsh FS (
1994
) Signal transduction events underlying neurite outgrowth stimulated by cell adhesion molecules.
Curr Opin Neurobiol
 
4
:
49
–55.
Doherty P, Cohen J, Walsh FS (
1990
) Neurite outgrowth in response to transfected N-CAM changes during development and is modulated by polysialic acid.
Neuron
 
5
:
209
–219.
Doherty P, Ashton SV, Moore SE, Walsh FS (
1991
) Morphoregulatory activities of NCAM and N-cadherin can be accounted for by G protein-dependent activation of L- and N-type neuronal Ca2+ channels.
Cell
 
67
:
21
–33.
Doyle E, Nolan PM, Bell R, Regan CM (
1992
) Hippocampal NCAM180 transiently increases sialylation during the acquisition and consolidation of a passive avoidance response in the adult rat.
J Neurosci Res
 
31
:
513
–523.
Edelman GM, Chuong CM (
1982
) Embryonic to adult conversion of neural cell adhesion molecules in normal and staggerer mice.
Proc Natl Acad Sci USA
 
79
:
7036
–7040.
Fairén A, Valverde F (
1980
) A specialized type of neuron in the visual cortex of cat: a Golgi and electron microscope study of chandelier cells.
J Comp Neurol
 
194
:
761
–779.
Fields RD, Itoh K (
1996
) Neural cell adhesion molecules in activity-dependent development and synaptic plasticity.
Trends Neurosci
 
19
:
473
–480.
Finne J, Makela PH (
1985
) Cleavage of the polysialosyl units of brain glycoproteins by a bacteriophage endosialidase. Involvement of a long oligosaccharide segment in molecular interactions of polysialic acid.
J Biol Chem
 
260
:
1265
–1270.
Finne J, Finne U, Deagostini-Bazin H, Goridis C (
1983
) Occurrence of alpha 2–8 linked polysialosyl units in a neural cell adhesion molecule.
Biochem Biophys Res Commun
 
112
:
482
–487.
Fonseca M, Soriano E, Ferrer I, Martínez A, Tunon T (
1993
) Chandelier cell axons identified by parvalbumin-immunoreactivity in the normal human temporal cortex and in Alzheimer's disease.
Neuroscience
 
55
:
1107
–1116.
Fox GB, Kennedy N, Regan CM (
1995
) Polysialylated neural cell adhesion molecule expression by neurons and astroglial processes in the rat dentate gyrus declines dramatically with increasing age.
Int J Dev Neurosci
 
13
:
663
–672.
Freund TF, Martin KA, Smith AD, Somogyi P (
1983
) Glutamate decarboxylase-immunoreactive terminals of Golgi-impregnated axo-axonic cells and of presumed basket cells in synaptic contact with pyramidal neurons of the cat's visual cortex.
J Comp Neurol
 
221
:
263
–278.
Fritschy JM, Weinmann O, Wenzel A, Benke D (
1998
) Synapse-specific localization of NMDA and GABA(A) receptor subunits revealed by antigen-retrieval immunohistochemistry.
J Comp Neurol
 
390
:
194
–210.
Goridis C, Brunet JF (
1992
) NCAM: structural diversity, function and regulation of expression.
Semin Cell Biol
 
3
:
189
–197.
Hoffman S, Sorkin BC, White PC, Brackenbury R, Mailhammer R, Rutishauser U, Cunningham BA, Edelman GM (
1982
) Chemical characterization of a neural cell adhesion molecule purified from embryonic brain membranes.
J Biol Chem
 
257
:
7720
–7729.
Hortsch M (
1996
) The L1 family of neural cell adhesion molecules: old proteins performing new tricks.
Neuron
 
17
:
587
–593.
Insausti R, Tuñon T, Sobreviela T, Insausti AM, Gonzalo LM (
1995
) The human entorhinal cortex: a cytoarchitectonic analysis.
J Comp Neurol
 
355
:
171
–198.
Jones EG (1984) Laminar distribution of cortical efferent cells. In: Cellular components of the cerebral cortex (Peters A, Jones EG, eds). New York: Plenum Press.
Kiss JZ, Rougon G (
1997
) Cell biology of polysialic acid.
Curr Opin Neurobiol
 
7
:
640
–646.
Kiss JZ, Wang C, Olive S, Rougon G, Lang J, Baetens D, Harry D, Pralong WF (
1994
) Activity-dependent mobilization of the adhesion molecule polysialic NCAM to the cell surface of neurons and endocrine cells.
EMBO J
 
13
:
5284
–5292.
Landmesser L, Dahm L, Tang JC, Rutishauser U (
1990
) Polysialic acid as a regulator of intramuscular nerve branching during embryonic development.
Neuron
 
4
:
655
–667.
Lewis DA (
2000
) GABAergic local circuit neurons and prefrontal cortical dysfunction in schizophrenia.
Brain Res Rev
 
31
:
270
–276.
Lewis DA, Pierri JN, Volk DW, Melchitzky DS, Woo TW (
1999
) Altered GABA neurotransmission and prefrontal cortical dysfunction in schizophrenia.
Biol Psychiat
 
46
:
616
–626.
Luthi A, Mohajeri H, Schachner M, Laurent JP (
1996
) Reduction of hippocampal long-term potentiation in transgenic mice ectopically expressing the neural cell adhesion molecule L1 in astrocytes.
J Neurosci Res
 
46
:
1
–6.
Marco P, Sola RG, Pulido P, Alijarde MT, Sanchez A, Ramon, DeFelipe J (
1996
) Inhibitory neurons in the human epileptogenic temporal neocortex. An immunocytochemical study.
Brain
 
119
:
1327
–1347.
Mikkonen M, Soininen H, Kalvianen R, Tapiola T, Ylinen A, Vapalahti M, Paljarvi L, Pitkanen A (
1998
) Remodeling of neuronal circuitries in human temporal lobe epilepsy: increased expression of highly polysialylated neural cell adhesion molecule in the hippocampus and the entorhinal cortex.
Ann Neurol
 
44
:
923
–934.
Mikkonen M, Soininen H, Tapiola T, Alafuzoff I, Miettinen R (
1999
) Hippocampal plasticity in Alzheimer's disease: changes in highly polysialylated NCAM immunoreactivity in the hippocampal formation.
Eur J Neurosci
 
11
:
1754
–1764.
Miller PD, Chung WW, Lagenaur CF, DeKosky ST (
1993
) Regional distribution of neural cell adhesion molecule (N-CAM) and L1 in human and rodent hippocampus.
J Comp Neurol
 
327
:
341
–349.
Miragall F, Kadmon G, Husmann M, Schachner M (
1988
) Expression of cell adhesion molecules in the olfactory system of the adult mouse: presence of the embryonic form of N-CAM.
Dev Biol
 
129
:
516
–531.
Muller D, Wang C, Skibo G, Toni N, Cremer H, Calaora V, Rougon G, Kiss JZ (
1996
) PSA-NCAM is required for activity-induced synaptic plasticity.
Neuron
 
17
:
413
–422.
Muller D, Djebbara-Hannas Z, Jourdain P, Vutskits L, Durbec P, Rougon G, Kiss JZ (
2000
) Brain-derived neurotrophic factor restores long-term potentiation in polysialic acid-neural cell adhesion molecule-deficient hippocampus.
Proc Natl Acad Sci USA
 
97
:
4315
–4320.
Nothias F, Vernier P, von Boxberg Y, Mirman S, Vincent JD (
1997
) Modulation of NCAM polysialylation is associated with morpho-functional modifications in the hypothalamo-neurohypophysial system during lactation.
Eur J Neurosci
 
9
:
1553
–1565.
Peters A, Proskauer CC, Ribak CE (
1982
) Chandelier cells in rat visual cortex.
J Comp Neurol
 
206
:
397
–416.
Rockland KS (1997) Elements of cortical architecture: hierarchy revisited. In: Cerebral cortex (Rockland KS, Kadmon G, Peters A, eds), pp. 243–294. New York: Plenum Press.
Ronn LC, Berezin V, Bock E (
2000
) The neural cell adhesion molecule in synaptic plasticity and ageing.
Int J Dev Neurosci
 
18
:
193
–199.
Rothbard JB, Brackenbury R, Cunningham BA, Edelman GM (
1982
) Differences in the carbohydrate structures of neural cell-adhesion molecules from adult and embryonic chicken brains.
J Biol Chem
 
257
:
11064
–11069.
Rutishauser U, Acheson A, Hall AK, Mann DM, Sunshine J (
1988
) The neural cell adhesion molecule (NCAM) as a regulator of cell–cell interactions.
Science
 
240
:
53
–57.
Sadoul R, Hirn M, Deagostini-Bazin H, Rougon G, Goridis C (
1983
) Adult and embryonic mouse neural cell adhesion molecules have different binding properties.
Nature
 
304
:
347
–349.
Santoni MJ, Barthels D, Barbas JA, Hirsch MR, Steinmetz M, Goridis C, Wille W (
1987
) Analysis of cDNA clones that code for the trans-membrane forms of the mouse neural cell adhesion molecule (NCAM) and are generated by alternative RNA splicing.
Nucleic Acids Res
 
15
:
8621
–8641.
Schmidt S, Braak E, Braak H (
1993
) Parvalbumin-immunoreactive structures of the adult human entorhinal and transentorhinal region.
Hippocampus
 
3
:
459
–470.
Schuch U, Lohse MJ, Schachner M (
1989
) Neural cell adhesion molecules influence second messenger systems.
Neuron
 
3
:
13
–20.
Seki T, Arai Y (
1993
) Distribution and possible roles of the highly polysialylated neural cell adhesion molecule (NCAM-H) in the developing and adult central nervous system.
Neurosci Res
 
17
:
265
–290.
Somogyi P, Freund TF, Cowey A (
1982
) The axo-axonic interneuron in the cerebral cortex of the rat, cat and monkey.
Neuroscience
 
7
:
2577
–2607.
Somogyi P, Nunzi MG, Gorio A, Smith AD (
1983
) A new type of specific interneuron in the monkey hippocampus forming synapses exclusively with the axon initial segments of pyramidal cells.
Brain Res
 
259
:
137
–142.
Somogyi P, Smith AD, Nunzi MG, Gorio A, Takagi H, Wu JY (
1983
) Glutamate decarboxylase immunoreactivity in the hippocampus of the cat: distribution of immunoreactive synaptic terminals with special reference to the axon initial segment of pyramidal neurons.
J Neurosci
 
3
:
1450
–1468.
Somogyi P, Freund TF, Hodgson AJ, Somogyi J, Beroukas D, Chubb IW (
1985
) Identified axo-axonic cells are immunoreactive for GABA in the hippocampus and visual cortex of the cat.
Brain Res
 
332
:
143
–149.
Squire LR, Zola SM (
1996
) Structure and function of declarative and nondeclarative memory systems.
Proc Natl Acad Sci USA
 
93
:
13515
–13522.
Sunshine J, Balak K, Rutishauser U, Jacobson M (
1987
) Changes in neural cell adhesion molecule (NCAM) structure during vertebrate neural development.
Proc Natl Acad Sci USA
 
84
:
5986
–5990.
Szele FG, Dowling JJ, Gonzales C, Theveniau M, Rougon G, Chesselet MF (
1994
) Pattern of expression of highly polysialylated neural cell adhesion molecule in the developing and adult rat striatum.
Neuroscience
 
60
:
133
–144.
Szentagothai J, Arbib MA (
1974
) Conceptual models of neural organization.
Neurosci Res Program Bull
 
12
:
305
–510
Tang J, Landmesser L, Rutishauser U (
1992
) Polysialic acid influences specific pathfinding by avian motoneurons.
Neuron
 
8
:
1031
–1044.
Theodosis DT, Rougon G, Poulain DA (
1991
) Retention of embryonic features by an adult neuronal system capable of plasticity: polysialylated neural cell adhesion molecule in the hypothalamo-neurohypo-physial system.
Proc Natl Acad Sci USA
 
88
:
5494
–5498.
Troy FA (
1992
) Polysialylation: from bacteria to brains.
Glycobiology
 
2
:
5
–23.
White EL (1989) Cortical circuits: synaptic organization of the cerebral cortex. Structure, function and theory. Boston, MA: Birkhauser.
Witter MP (
1993
) Organization of the entorhinal–hippocampal system: a review of current anatomical data.
Hippocampus
 
3
(special issue):
33
–44.