GLORIA

GEOMAR Library Ocean Research Information Access

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The direct and transynaptic effects of lesions of the basal forebrain induced by α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and ibotenic acid were investigated using quantitative in situ hybridization histochemistry. Probes complementary to the sequences of choline acetyltransferase mRNA, glutamate decarboxylase mRNA and preproenkephalin mRNA were used to assess direct lesion effects within the basal forebrain and probes for postsynaptic M-1 and M-3 muscarinic receptors were used to assess long-term changes in neocortical muscarinic receptor mRNA expression following cholinergic deafferentation. AMPA-induced basal forebrain lesions destroyed significantly more neurons that expressed choline acetyltransferase mRNA than ibotenic acid-induced lesions (90 versus 60%), but significantly fewer neurons which expressed either glutamate decarboxylase or preproenkephalin mRNA (61 versus 83% reduction in glutamate decarboxylase mRNA and 56 versus 79% reduction in preproenkephalin mRNA). AMPA-induced lesions did, however, destroy a significant proportion of the neurons which expressed glutamate decarboxylase and preproenkephalin mRNA (-60%). The neurons spared following AMPA-induced lesions were typically situated dorsolaterally within the dorsal pallidum, although neurons expressing glutamate decarboxylase or preproenkephalin mRNA were frequently observed within the areas of greatest cholinergic neuronal loss, i.e. the region of the nucleus basalis magnocellularis. These findings suggest that there is a population of non-cholinergic pallidal neurons which are insensitive to AMPA but not to ibotenic acid, reflecting a possibly heterogeneous distribution of NMDA and non-NMDA subtypes of glutamate receptors within the rat basal forebrain. AMPA-induced lesions of the basal forebrain were, however, without significant effect on the levels of expression of M-1 and M-3 muscarinic receptor mRNAs in the cerebral neocortex.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The regional distribution of neurons containing a-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor (GluR1-4) subunit immunoreactivity, relative to the distribution of cholinergic neurons within the basal forebrain of rats, was assessed using single- and dual-antigen immunocytochemistry. Analysis of serial sections stained with antibodies to nerve growth factor receptor (NGFr) and antibodies against each of the AMPA receptor subunits, GluR1-4, revealed a regional codistribution between NGFr- and GluR1- and GluR4-immunoreactive neurons in the medial septum, diagonal band nuclei and nucleus basalis magnocellularis. Quantitative dual-labelling immunocytochemistry using NGFr in combination with each of the GluR antibodies revealed 〉65% colocalization between NGFr and GluR4 in each of the major cholinergic nuclei in the basal forebrain and 10–15% colocalization between NGFr, GluR1 and GluR2-3. The reticular nucleus of the thalamus, a structure known to be highly susceptible to AMPA-induced neurotoxicity, expressed GluR4 immunoreactivity exclusively. The observation that cholinergic neurons of the basal forebrain are also highly sensitive to AMPA and express the GluR4 subunit suggests that GluR4 may be important in AMPA receptor-mediated excitotoxicity.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Using radioactive in situ hybridization, we have mapped the expression of Huntingtin-associated protein (HAP1) mRNA in rat brain at developmental stages (E12–E19, P0–P21), in adult rats (3 months) and in ‘aged’ (19–21 months) rats. Using two pairs of 45mer oligonucleotide probes specific for HAP1A and a probe which recognizes regions of both the HAP1A and HAP1B mRNA sequences (panHAP1), we find that the expression of HAP1 mRNA is specific to the CNS and restricted predominantly to anatomically connected limbic structures, particularly the amygdala (medial and corticomedial nuclei), the hypothalamus (arcuate, preoptic, paraventricular and lateral hypothalamic area), bed nucleus of the stria terminalis (BNST) and the lateral septal nuclei. HAP1 mRNA was detected in embryos at E12 and displayed a prevalent distribution in the developing limbic structures by E15. In aged, 19–21-months-old, rats there is a downregulation of HAP1 mRNA expression across all CNS loci where HAP1 was previously abundant. The lowest levels of HAP1 mRNA expression corresponded with the areas of greatest pathological cell loss in Huntington’s disease (HD); the caudate putamen, globus pallidus and neocortex. These observations support the suggestion that HAP1 plays an important role in the neuropathology of HD.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: N-methyl-d-aspartate (NMDA) and non-NMDA receptor-mediated manipulations of the cortical cholinergic input arising from the basal forebrain differentially affect cognitive function. We used [14C]-2-deoxyglucose autoradiography in conscious rats to map the effects of excitatory amino acid agonist infusions into the nucleus basalis magnocellularis (NBM) on cerebral functional activity, as reflected by local rates of glucose utilization. Acute stimulation of NBM neurones by local infusion of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), 15 min before glucose use measurement, resulted in glucose use reductions in nine cortical regions innervated by NBM efferents including prefrontal, frontal, sensorimotor and cingulate cortices. NMDA infusions altered glucose use in two cortical areas. Both AMPA and NMDA markedly increased glucose use in the striatum and globus pallidus, with concomitant perturbations in striato-pallidal projection targets including the substantia nigra, entopeduncular nucleus, subthalamic nucleus and lateral habenular nucleus. In contrast, the GABAA agonist muscimol did not affect glucose use in the NBM or neocortical regions, but induced glucose use increases in several subcortical nuclei including the substantia nigra and entopeduncular nucleus.The delayed effects of excitotoxic lesions were assessed 3 weeks after basal forebrain infusions of AMPA, NMDA, ibotenate or quisqualate. Statistically significant glucose use changes only occurred in the hypothalamus after NMDA, and the NBM after ibotenate infusions, although reduced cortical metabolism was apparent following AMPA-induced lesions of the NBM. Results support a dissociation between the functional sequelae of NMDA and non-NMDA receptor-mediated events in the basal forebrain, and long-term compensatory functional adaptation following cortical denervation.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1432-1106
    Keywords: c-fos ; FOS ; Striatopallidal system ; Subthalamic nucleus ; Nucleus basalis magnocellularis ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In these experiments, induction of the immediate early gene c-fos following excitation of striatal neurons has been used to investigate the organization of the ventral and dorsal striatopallidal systems and the relationship between striatal neurons and cholinergic neurons of the nucleus basalis magnocellularis (of Meynert, nbM). The results demonstrate that FOS immunoreactivity (ir) can be detected in ventral and dorsal striatal neurons following infusions of the non-N-methyl-d-aspartic acid (NMDA) glutamate receptor agonist α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA). This activation and increased expression of FOS in striatal neurons was itself associated with the sustained appearance of FOS-ir in neurons of the ipsilateral ventral and dorsal pallidum, subthalamic nucleus and some thalamic nuclei. Infusions of AMPA into the ventral striatum (VS), but not the dorsal striatum (DS), also resulted in the appearance of FOS-ir in a proportion (17%) of the cholinergic neurons of the nbM. By combining the retrograde transport of Fluoro-Gold with FOS immunocytochemistry, it was also possible to demonstrate that approximately 46% and 58% of the pallidal neurons containing FOS-ir after infusions of AMPA into the VS or DS, respectively, directly project to the subthalamic nucleus. Taken together, these observations suggest that visualizing the protein product of transsynaptic c-fos induction provides an effective way to study the topographic and transsynaptic, within-system consequences of striatal activation.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1432-1106
    Keywords: c-fos ; FOS ; Basal forebrain ; Excitatory ammino acids ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract These experiments investigated, by studying patterns of c-fos expression, the distribution of neurons activated or destroyed by the infusion into the basal forebrain of various excitatory amino acids at toxic and subtoxic doses. The results of experiment 1 showed that N-methyl-d-aspartic acid (NMDA), quisqualic acid and αamino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) differentially increased the expression of c-fos in magnocellular cholinergic nucleus basalis, dorsal and ventral pallidal neurons. AMPA was the most, and NMDA the least, effective in inducing FOS in nucleus basalis magnocellularis (nbM) neurons, with quisqualic acid having an intermediate effect, whereas the reverse was true in terms of the induction of FOS in pallidal neurons. In experiment 2, it was demonstrated that, in animals with ibotenic acid-induced lesions of the basal forebrain that were targetted on the nbM, virtually no pallidal neurons could be visualized that expressed FOS following AMPA-induced excitation of the dorsal and ventral striatum. By contrast, in animals with AMPA-induced lesions of the nbM, excitation of the striatum was followed by the expression of FOS in many dorsal and ventral pallidal neurons. Thus, infusions of AMPA into the basal forebrain appears preferentially to activate or destroy, depending on the concentration infused, cholinergic nbM neurons, whereas ibotenic acid or NMDA preferentially destroys or activates neurons of the dorsal and ventral pallidum. These results provide novel and complementary information regarding the organization of the basal forebrain and allow a clearer understanding of the different behavioural consequences of NMDA agonist-induced and non-NMDA agonist-induced excitotoxic lesions of this area.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1546-170X
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Mutations in two recently identified genes appear to cause the majority of early–onset familial Alzheimer's disease (FAD). These two novel genes, presenilin 1 (PS1) and presenilin 2 (PS2) are members of an evolutionarily conserved gene family. The normal biological role(s) of the presenilins ...
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...