Stratum radiatum

Chronic treatment with EGb 761 in mice created histological changes in the hippocampus (Barkats et al. 1995). Increases are seen in the projection field of hippocampal mossy fibers and a reduction in the area of the stratum radiatum. These changes are hypothesized to result from... 

Hippocampal slices (400-500 frm) were quickly prepared from male Wistar rats (8- to 9-weeks-old) and maintained in a chamber at 35 °C, where they were continuously perfused with artificial cerebrospinal fluid as described in our previous paper [11]. A bipolar tungsten electrode was placed in the stratum radiatum to stimulate Schaffer collateral and commissural afferents. The evoked potential was extracellularly recorded from the pyramidal cell layer of the CA1 subfield with a glass capillary microelectrode. A single test stimulation (0.05 msec duration) was applied at intervals of 30 sec. Drugs were delivered by perfusion. To induce potentiation of the evoked potentials, tetanic stimulation was applied at the same intensity through the same stimulating electrode as used for the test stimulation. The magnitude of LTP was evaluated by the population spike amplitude 30 min after tetanic stimulation. 

Regional distribution studies indicate that the highest density of kainate receptor occurs in the stratum lucidum of the hippocampus (mossy fiber system) and in the inner and outer layers of the neocortex. The highest density of NMDA receptors is found in the hippocampus, stratum radiatum, and in the striatum, thalamus, and cerebral cortex. The distribution of AMPA receptors is similar to that of NMDA receptors, but in the cerebellum AMPA receptors predominate in the molecular layer... 

Fig. 6.4 GAT-3 immunoreactivity in field CA3 of the hippocampus. A section from a normal rat, showing occasional labeled glial cell bodies (arrow) and large numbers of processes in the neuropil (asterisk). B section from a 1 day post-kainate injected rat showing loss of labeling in an affected area (asterisk). Abbreviations SO, stratum oriens SR stratum pyramidale and SR stratum radiatum. Scale = 50 /u,m. Reproduced with kind permission from Zhu et al., 2004, Journal ofNeuroscience Research 77 402 109. Wiley-Liss...

In the hippocampus, presynaptic P2X2 receptors mediated increases in the frequencies of miniature excitatory postsynaptic currents in stratum radiatum intemeu-rons, but not in pyramidal neurons (Khakh et al. 2003). Glutamate release from hippocampal mossy fibers, in contrast, was found to be inhibited by P2X7 receptor activation (Armstrong et al. 2002). 

B. Colocalization ofmGlulaand CB1 Receptors in a Subset of Stratum Radiatum Hippocampal Interneurons... 

Fig. 2. Confocal microscopic images of an organotypic hippocampal slice depicting an interneuron displaying both CB1- and mGlula-like immunoreactivity in the stratum radiatum of the CA1 region. High magnification displays a characteristic membrane staining for mGlul a (A) and a typical punctate labeling pattern for CB1 (B). Scale bar 50 fim.

Racca C, Stephenson FA, Streit P, Roberts JDB, Somogyi P (2000) NMDA receptor content of synapses in stratum radiatum of the hippocampal CAl area. 7 Neurosci 20 2512-2522. 

The density of GLAST in the molecular layer is as high as 18,000 GLAST molecules per p.m- tissue (molecular layer) or about 4700 molecules per p.m Bergmann glia cell membrane (Lehre and Danbolt, 1998). The concentration of GLAST in the hippocampus (stratum radiatum, CAl) is 3200 molecules per p.m- tissue or about 2300 per p.m astroglial cell membrane. 

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