Enhanced carbodiimide fixation for immunohistochemistry: application to the comparative distributions of N-acetylaspartylglutamate and N-acetylaspartate immunoreactivities in rat brain.

Moffett, John R.; Namboodiri, M. A. A.; Neale, Joseph H.

doi:10.1177/41.4.8450195

Cited by 117 publications

(116 citation statements)

References 26 publications

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“…These investigators also showed that pre-incubation of serum-deprived astrocytes in culture with unlabeled NAA resulted in significantly increased NAAG biosynthesis from tritiated glutamate during the course of a 90 minute incubation period. These findings are highly suggestive of the existence of a NAAG synthetase enzyme which ligates NAA and glutamate, however they differ somewhat from the results in several other studies which have shown that astrocytes do not express detectable levels of NAAG (Moffett et al, 1993;Moffett and Namboodiri, 1995;Passani et al, 1998). It is possible that certain in vitro conditions, including serum deprivation, induce astrocytes in culture to produce high levels of NAAG (Cassidy and Neale, 1993a).…”

Section: Naa Concentration Increases Naag Biosynthesis-the Evidence Tcontrasting

confidence: 72%

“…Further, other acetylated compounds may contribute 10% or more to the so-called "NAA signal" in MRS, and some of these compounds may be more resistant to decline after injury than NAA (Pouwels and Frahm, 1997;Sager et al, 2001). Finally, we have observed that the method used to perform NAA immunohistochemistry (Moffett et al, 1993;Moffett and Namboodiri, 1995) causes strong, non-specific antibody binding to damaged brain tissue (unpublished observations), as was observed by Sager and colleagues in areas bordering the ischemic injury (Sager et al, 2000).…”

Section: Magnetic Resonance Spectroscopy and Imaging Of Naasupporting

confidence: 57%

“…It was not until the 1990s that specific antibodies to protein-coupled NAA, including monoclonal antibodies (Simmons et al, 1991) and polyclonal antibodies Moffett et al, 1993;Moffett and Namboodiri, 1995;, permitted the cellular localization of NAA. These studies demonstrated that NAA was present predominantly in neurons and their processes, and that the levels varied substantially between different neuronal populations.…”

Section: Naa Synthesismentioning

confidence: 99%

“…These studies demonstrated that NAA was present predominantly in neurons and their processes, and that the levels varied substantially between different neuronal populations. Immunohistochemical studies on the distribution of NAA in the rat brain showed notably high levels of NAA in cortical pyramidal neurons (see Figure 3), many granule cell populations throughout the brain, mitral cells of the olfactory bulb (Simmons et al, 1991), neurons of the olfactory tubercle (Moffett and Namboodiri, 1995), the dorsal column nuclei and many neurons throughout the brainstem and spinal cord (Moffett et al, 1993). Axons in many fiber tracts were moderately stained for NAA, including the corpus callosum, corticospinal tracts, optic nerves and tracts, lateral olfactory tracts and stria terminalis (Moffett and Namboodiri, 1995).…”

Section: Naa Synthesismentioning

confidence: 99%

“…It is synthesized enzymatically from NAA and glutamate (Arun et al, 2006;Boltshauser et al, 2004;Cangro et al, 1987;Gehl et al, 2004) and is localized in specific types of neurons throughout the CNS (Anderson et al, 1987;Moffett et al, 1993;Moffett and Namboodiri, 1995;Tieman et al, 1991;Tieman and Tieman, 1996). NAAG is released from synapses in a calcium dependent manner (Williamson et al, 1991), and acts through presynaptic metabotropic glutamate receptors to modulate the release of classical neurotransmitters (Xi et al, 2002;Zhao et al, 2001).…”

Section: Naa and Naag Biosynthesismentioning

confidence: 99%

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N-Acetylaspartate in the CNS: From neurodiagnostics to neurobiology

Moffett

Ross

Arun

et al. 2007

Progress in Neurobiology

1,230

1,126

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The brain is unique among organs in many respects, including its mechanisms of lipid synthesis and energy production. The nervous system-specific metabolite N-acetylaspartate (NAA), which is synthesized from aspartate and acetyl-coenzyme A in neurons, appears to be a key link in these distinct biochemical features of CNS metabolism. During early postnatal CNS development, the expression of lipogenic enzymes in oligodendrocytes, including the NAA-degrading enzyme aspartoacylase (ASPA), is increased along with increased NAA production in neurons. NAA is transported from neurons to the cytoplasm of oligodendrocytes, where ASPA cleaves the acetate moiety for use in fatty acid and steroid synthesis. The fatty acids and steroids produced then go on to be used as building blocks for myelin lipid synthesis. Mutations in the gene for ASPA result in the fatal leukodystrophy Canavan disease, for which there is currently no effective treatment. Once postnatal myelination is completed, NAA may continue to be involved in myelin lipid turnover in adults, but it also appears to adopt other roles, including a bioenergetic role in neuronal mitochondria. NAA and ATP metabolism appear to be linked indirectly, whereby acetylation of aspartate may facilitate its removal from neuronal mitochondria, thus favoring conversion of glutamate to alpha ketoglutarate which can enter the tricarboxylic acid cycle for energy production. In its role as a mechanism for enhancing mitochondrial energy production from glutamate, NAA is in a key position to act as a magnetic resonance spectroscopy marker for neuronal health, viability and number. Evidence suggests that NAA is a direct precursor for the enzymatic synthesis of the neuron specific dipeptide N-acetylaspartylglutamate, the most concentrated neuropeptide in the human brain. Other proposed roles for NAA include neuronal osmoregulation and axon-glial signaling. We propose that NAA may also be involved in brain nitrogen balance. Further research will be required to more fully understand the biochemical functions served by NAA in CNS development and activity, and additional functions are likely to be discovered.

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Section: Naa Concentration Increases Naag Biosynthesis-the Evidence Tcontrasting

confidence: 72%

Section: Magnetic Resonance Spectroscopy and Imaging Of Naasupporting

confidence: 57%

Section: Naa Synthesismentioning

confidence: 99%

Section: Naa Synthesismentioning

confidence: 99%

Section: Naa and Naag Biosynthesismentioning

confidence: 99%

See 3 more Smart Citations

N-Acetylaspartate in the CNS: From neurodiagnostics to neurobiology

Moffett

Ross

Arun

et al. 2007

Progress in Neurobiology

1,230

1,126

View full text Add to dashboard Cite

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N-acetylaspartylglutamate activates cyclic AMP-coupled metabotropic glutamate receptors in cerebellar astrocytes

Wróblewska

Santi

Neale

1998

Glia

106

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Light and electron microscopic immunohistochemical localization of N-acetylaspartylglutamate NAAG in the olivocerebellar pathway of the rat

Renno

Lee

Beitz

1997

Synapse

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The inferior olive (IO) is the sole contributor of climbing fibers (CF) to the Purkinje cells of the cerebellar cortex. Although the anatomy and the connectivity between the IO and the cerebellum have been well established, there is still controversy regarding the neurotransmitter systems mediating olivocerebellar projections. The excitatory amino acids, glutamate (Glu) and aspartate (Asp), have both been considered as neurotransmitter candidates of olivocerebellar projections in the rat. More recently N-acetylaspartylglutamate (NAAG) has also been proposed as a transmitter of cerebellar climbing fibers based on biochemical and electrophysiological data. The aim of the present study was to determine whether NAAG immunoreactivity is present in the IO and CF at the light and electron microscopic levels and to quantitate the amount of immunogold labeling in olivary neurons and climbing fiber terminals containing this dipeptide. A polyclonal antisera against NAAG was utilized with a peroxidase-labeled avidin-biotin procedure to demonstrate these immunoreactive neurons in the IO at the light microscopic level. Approximately 45% of olivary neurons display NAAG-like immunoreactivity, and their distribution is unevenly clustered throughout the inferior olive. Using postembedding immunogold electron microscopy in combination with quantitative procedures, we found the highest densities of gold particles in the axonal terminals synapsing on olivary neurons (101.0 particles/microns2), in CF terminals (96.3 particles/microns2), and in some mossy fiber terminals (101.0 particles/microns2). Approximately half of the climbing fiber terminals examined were unlabeled. Moderate labeling occurred in CF axons (70.8 particles/microns2), while IO neuronal perikarya were lightly but significantly labeled (41.6 particles/microns2). The localization of NAAG in the subset of cerebellar climbing fiber terminals provides anatomical support for the hypothesis that NAAG may serve as a neurotransmitter/neuromodulator candidate in the olivocerebellar pathway.

show abstract

Enhanced carbodiimide fixation for immunohistochemistry: application to the comparative distributions of N-acetylaspartylglutamate and N-acetylaspartate immunoreactivities in rat brain.

Cited by 117 publications

References 26 publications

N-Acetylaspartate in the CNS: From neurodiagnostics to neurobiology

N-Acetylaspartate in the CNS: From neurodiagnostics to neurobiology

N-acetylaspartylglutamate activates cyclic AMP-coupled metabotropic glutamate receptors in cerebellar astrocytes

Light and electron microscopic immunohistochemical localization of N-acetylaspartylglutamate NAAG in the olivocerebellar pathway of the rat

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