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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Unilateral aspiration lesions of the rostral supracallosal stria/cingulum bundle and fimbria-fornix were performed on adult female rats. Ten and 24 days post lesioning, an elevation (17%; p〈0.01) of total muscarinic receptors was observed in lesioned versus control hippocampi. By using antisera selective for each of the five molecularly defined subtypes (m1-m5) of muscarinic receptors, significant changes were observed in the levels of expression for at least four receptor proteins. Three receptor subtypes increased in density: m1 by 14% (from 943 to 1,078 fmol/mg); m3 by 77% (from 150 to 268 fmol/ mg); and m4 by 29% (from 220 to 285 fmol/mg). In contrast, a 22% decrease in the density of m2 receptors was found (from 220 to 173 fmol/mg). Detectable levels of m5 receptors were low in the hippocampus (∼1% of total receptors), and reliable measurements were not obtained. The directions of these changes are likely to be related to the pre- or postsynaptic localization of these receptor subtypes.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: A polyclonal antibody for the NMDA receptor subunit NR2D has been developed that identifies an ∼160-kDa band on immunoblots from NR2D transfected cells and CNS tissues. No cross-reactivity is seen with other NMDA receptor subunits. The NR2D receptor subunit is N-glycosylated in both brain and transfected cells. Transfected cells expressing NR2D are immunofluorescently labeled, whereas untransfected cells or cells transfected with other NMDA receptor subunit cDNAs are not. Similarly, the NR2D subunit is selectively and quantitatively immunoprecipitated, whereas the NR1, NR2A, or NR2B subunit is not. The relative densities of the NR2D subunit in nine areas of postnatal day 7 and adult rat brains have been determined by quantitative immunoblotting. NR2D was expressed at highest levels in the thalamus, midbrain, medulla, and spinal cord, whereas intermediate levels of this subunit were found in the cortex and hippocampus. Low or undetectable levels were seen in the olfactory bulb, striatum, and cerebellum. Following a peak after the first week of birth, NR2D protein levels decreased by about twofold in adulthood in all rat brain regions examined. More complete ontogenic profiles were determined for the diencephalon, telencephalon, and spinal cord where similar ontogenic patterns were seen. NR2D protein is present at high levels at embryonic stages of development, rises to a peak at postnatal day 7, and decreases but remains measurable during late postnatal life. This study demonstrates the generation and characterization of an antibody selective for the NR2D NMDA receptor subunit as well as a determination of the distribution and ontogenic profile of this subunit in rat brain. The results suggest that native NMDA receptors containing the NR2D subunit may have functional roles not only in the young brain but also in adult brain.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Selective antisera for NMDA receptor subunits NR2A and NR2B have been developed. Each antiserum identifies a single band on an immunoblot at ∼175 kDa that appears to be the appropriate subunit of the NMDA receptor. Using these antisera the relative densities of the subunits in eight areas of adult rat brain have been determined. The NR2A subunit was found to be at its highest level in hippocampus and cerebral cortex, to be at intermediate levels in striatum, olfactory tubercle, midbrain, olfactory bulb, and cerebellum, and to be at lowest levels in the pons-medulla. The NR2B subunit was found to be expressed at its highest levels in the olfactory tubercle, hippocampus, olfactory bulb, and cerebral cortex. Intermediate levels were expressed in striatum and midbrain, and low levels were detected in the pons-medulla. No signal for NR2B was found in the cerebellum. These regional distributions were compared with that for [3H]MK-801 binding sites. It was found that although the distribution of the NR2A subunit corresponds well with radioligand binding, the distribution of the NR2B subunit does not. The ontogenic profiles of NR2A and NR2B subunits in the rat cerebellum were also determined. Just following birth [postnatal day (P) 2] NR2A subunits are undetectable, whereas NR2B subunits are expressed at amounts easily measurable. Beginning at about P12 the levels of NR2A rise rapidly to reach adult levels by P22. At the same time (P12), levels of NR2B protein begin to decline rapidly to reach undetectable levels by 22 days after birth. The results suggest that NMDA receptors are likely to be composed of different subunits in different parts of the brain and that even in the same tissue the receptors are likely to show different properties at various times during development due to alterations in the subunit composition of the receptor.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A synthetic peptide corresponding to the C-terminus of the α3 subunit of the rat neuronal nicotinic acetylcholine receptor (nAChR) was used to generate a rabbit polyclonal α3 antibody. The specificity of this antibody was characterized by immunoblotting, immunohistochemical and immunoprecipitation techniques. Using this antibody, the relative densities of the α3 subunit were quantitatively determined in different brain regions and in superior cervical ganglion (SCG). Among these regions, SCG, interpeduncular nucleus (IPN) and pineal gland showed the highest levels of α3 protein expression. Habenula and superior colliculi had intermediate levels of expression. Low levels were found in cerebral cortex, hippocampus and cerebellum. The ontogenic profile of the α3 subunit in the SCG was also determined. The α3 protein level is low at postnatal day (P 1), but increases rapidly during the first seven postnatal days. This level then plateaus and remains stable through postnatal day 35. These findings suggest that neuronal nAChRs containing the α3 subunit participate in important roles in specific regions of the rat brain and the SCG.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 75 (2000), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract : Differential assembly of N-methyl-D-aspartate (NMDA) receptor subunits determines their functional characteristics. Using in situ hybridization, we found a selective increase of the subunits NR1 and NR2A mRNA at 24 h in ventral motor neurons (VMN) caudal to a standardized spinal cord contusion injury (SCI). Other neuronal cell populations and VMN rostral to the injury site appeared unaffected. Significant up-regulation of NR2A mRNA also was seen 1 month after SCI in thoracic and lumbar VMN. The selective effects on VMN caudal to the injury site suggest that the loss of descending innervation leads to increased NMDA receptor subunit expression in these cells after SCI, which may alter their responses to glutamate. In contrast, protein levels determined by western blot analysis show decreased levels of NR2A 1 month after SCI in whole thoracic segments of spinal cord that included the injury sites. No effects of injury were seen on subunit levels in cervical or lumbar segments. Taken together with our previous study showing α-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptor subunit down-regulation after injury, our data suggest that glutamate receptor composition is significantly altered after SCI. These changes need to be taken into account to properly understand the function of, and potential pharmacotherapy for, the chronically injured spinal cord.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 71 (1998), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: A subunit-specific antibody against the N-methyl-d-aspartate (NMDA) receptor NR2D protein along with an antiphosphotyrosine antibody were employed to examine the developmental profile of the tyrosine phosphorylation of NR2D and its regulation by a protein phosphatase inhibitor in rat brain. NMDA receptor proteins from the thalamus at postnatal days 1, 7, 21, and 49 were solubilized under denaturing conditions and used in immunoprecipitations with these antibodies followed by quantitative immunoblot analysis of NR2D protein in the resulting immunopellets. The results indicate that the NR2D subunit is tyrosine phosphorylated in the brain. The quantified data examining the developmental profile of tyrosine phosphorylation of NR2D in the thalamus show that the level of tyrosine phosphorylation of NR2D protein increases five- to sixfold during development. In addition, the protein phosphatase inhibitor pervanadate (vanadyl hydroperoxide) was found to increase tyrosine phosphorylation of NR2D subunit threefold in brain slices, implying an active cycle of phosphorylation and dephosphorylation in situ. These studies demonstrate developmentally regulated tyrosine phosphorylation of NR2D protein in vivo, suggesting that tyrosine phosphorylation may be important for regulating the functions of this NMDA receptor subunit in the mammalian central nervous system.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Recordings of NMDA-activated currents from cerebellar granule neurons in culture revealed a developmental increase in current density accompanied by a slight decrease of the half-maximal effective concentration. At the same time, a decrease of NMDA receptors comprising NR2B subunits was demonstrated by the reduction in the antagonism of NMDA currents by ifenprodil. Ifenprodil antagonism increased after treatment for 24 h with KN93- and KN62-selective inhibitors of the Ca2+/calmodulin-dependent protein kinases (CaM kinases), indicating a selective increase of receptor containing NR2B subunit. This increase was observed at all ages tested: 4 days in vitro (DIV4), DIV6, and DIV13. Western blot analysis with specific NMDA receptor antibodies performed at DIV6 confirmed the electrophysiological data. At this age, the negative control KN92 was ineffective. The increasing ifenprodil antagonism after KN93 treatment was proportionally greater in cells at DIV13 than at DIV4. Treatment with NMDA (100 µM) of cerebellar cultures for 24 h produced a decrease in the NMDA-induced current density by almost 50% at all ages tested. Ifenprodil antagonism, however, was unchanged. We propose that the expression of NR2B subunits in cerebellar granule cells is selectively stimulated by the inhibition of CaM kinases.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 75 (2000), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: We investigated the ontogenic changes in expression of alternatively spliced forms of NR1 protein that contain the N1 cassette (exon 5) in comparison with the total population of NR1 within the rat cerebellum. The N1 cassette is strongly developmentally regulated in the cerebellum, with 〉80% of total NR1 protein in the adult rat containing the N1 cassette. In contrast, early in development, 〈20% of NR1 protein contained this cassette. Rat cortices from the same ages did not show an increase in the percent of NR1 protein expressing the N1 cassette, indicating that the developmental changes in the cerebellum are tissue-specific. As the N1 cassette is known to determine NMDA receptor properties, including spermine sensitivity and decay kinetics of glutamate-induced currents, changes in the characteristics of glutamate-activated currents in granule cells from cerebellar slices were compared at postnatal day 7 versus 14. Glutamate responses exhibited fast deactivation kinetics and reduced potentiation by spermine at day 14 while maintaining sensitivity to an NR2B-selective antagonist. These data are consistent with the possibility that N1 cassette expression may be a factor in the developmental changes in properties of extrasynaptic NMDA receptors in the cerebellum.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 757 (1995), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 96 (1974), S. 7747-7752 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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