Differential Distribution of Group I Metabotropic Glutamate Receptors during Rat Cortical Development

Abstract

Neurons in the rat cerebral cortex are enriched in group I metabotropic glutamate receptor (mGluR) subtypes and respond to their activation during development. To understand better the mechanisms by which mGluR1 and mGluR5 mediate these effects, the goal of this study was to elucidate the expression pattern and to determine the cellular and the precise subcellular localization of these two receptor subtypes in the rat neocortex and hippocampus during late prenatal and postnatal development. At the light microscopic level, mGluR1alpha and mGluR5 were first detected in the cerebral cortex with different expression levels at embryonic day E18. Thus, mGluR5 had a moderate expression, whereas mGluR1alpha was detected as a diffuse and weak labeling. mGluR5 was localized in some Cajal- Retzius cells as well as in other cell types, such as pioneer neurons of the marginal zone. During postnatal development, the distribution of the receptors dramatically changed. From P0 to around P10, mGluR1alpha was localized in identified, transient Cajal-Retzius cells of neocortex and hippocampus, until these cells disappear. In addition, a population of interneurons localized the receptor from the second/third postnatal week. In contrast, mGluR5 was localized mainly in pyramidal cells and in some interneurons, with a neuropilar staining throughout the cerebral cortex. At the electron microscopic level, the immunoreactivity for both group I mGluR subtypes was expressed postsynaptically. Using immunogold methods, mGluR1alpha and mGluR5 immunoreactivities were found throughout postnatal development at the edge of postsynaptic specialization of asymmetrical synapses. These results show that the two group I mGluRs have a differential expression pattern in neocortex and hippocampus that may suggest roles for the receptors in the early processing of cortical information and in the control of cortical developmental events.

Dual neurotoxic and neuroprotective role of metabotropic glutamate receptor 1 in conditions of trophic deprivation – Possible role as a dependence receptor

“…This is consistent with the toxic effect of mGlu1 antagonist CPCCOEt reported in differentiating Purkinje cells (Catania et al, 2001) and observations that mGlu1 expression is higher in neonatal and early postnatal than in the adult brain (Casabona et al, 1997;van den Pol et al, 1994). Moreover, mGlu1 is highly expressed in Cajal-Retzius cells of rat neocortex and hippocampus which are eliminated within ten days after birth (Lopez-Bendito et al, 2002). Because mGlu1 expression has been reported in a variety of peripheral tissues (Storto et al, a, Cerebellar granule cells were cultured in K25 NB medium supplemented with B27 for one week.…”

Ontogeny of postsynaptic density proteins at glutamatergic synapses

“…As in adults, these mGluRs often appear to be concentrated in perisynaptic regions (López-Bendito et al, 2002). In immunoblots (Fig.…”

“…The Shank/Homer dimer chain likely associates with the metabotropic GluRs, mGluR1 and mGluR5, which are found in hippocampus throughout postnatal development (Shigemoto et al, 1992;López-Bendito et al, 2002;Di Giorgi Gerevini et al, 2004). As in adults, these mGluRs often appear to be concentrated in perisynaptic regions (López-Bendito et al, 2002).…”

Group I Metabotropic Glutamate Receptors Bind to Protein Phosphatase 1C

“…PP1␥1 and associated mGluRs are also co-localized in the same subcellular compartments of neurons in other brain areas, e.g. in hippocampal interneurons of the stratum oriens and in dendrites of cerebellar purkinje cells (7,(42)(43)(44)(45).…”