Joseph Neale | Georgetown University (original) (raw)
Papers by Joseph Neale
Brain Research, Mar 1, 1987
European Journal of Neuroscience, May 1, 1991
Journal of comparative neurology, Nov 1, 1991
The acidic dipeptide N‐acetylaspartylglutamate (NAAG) was identified immunohistochemically within... more The acidic dipeptide N‐acetylaspartylglutamate (NAAG) was identified immunohistochemically within neurons of the visual pathways of two adult macaque monkeys which had undergone midsagittal sectioning of the optic chiasm 6 or 9 years earlier. In both temporal and nasal retinae, amacrine cells, including some displaced amacrine cells, expressed NAAG immunoreactivity. In temporal but not nasal retina, retinal ganglion cells were stained, as were their dendrites in‐the inner plexiform layer, and their axons in the optic nerve fiber layer. In nasal retina, the ganglion cells had degenerated because they were axotomized by the optic chiasm section. In the target regions of the retinal ganglion cells, the superior colliculus and the lateral geniculate nucleus (LGN), both neuropil and cell bodies were stained. In LGN, staining was confined to layers 2, 3, and 5, that is, to the layers innervated by the intact ipsilateral pathway. Immunoreactivity was also seen in the cells of layers 2, 3A, 4B, 5, and 6 of area 17 and layers 3 and 5 of area 18. The neuropil was stained in all layers of area 17, but more heavily in layers 1, 2, 4B, the bottom of 4Cβ, 5B, and 6B. Within 4C the staining was patchy; in tangential sections there were alternating bands of light and dark label which matched the ocular dominance bands demonstrated by cytochrome oxidase histochemistry in adjacent sections. This banding pattern is consistent with the presence of NAAG in geniculocortical terminals of the intact ipsilateral pathway and the absence of such terminals for the contralateral pathway, which had undergone transneuronal degeneration due to the optic chiasm sectioning. Overall, our results for monkey are very similar to those in cat and suggest that NAAG or a structurally related molecule may have a prominent role in the communication of visual signals at retinal, thalamic, and cortical levels.
Journal of Neurophysiology, 2003
Brain Research, Jul 1, 1988
Neuropeptides, May 1, 1993
Journal of Cell Biology, Jul 1, 1977
Journal of Neurochemistry, Apr 1, 1989
Abstract The γ‐aminobutyric acid (GABA) type A receptor was purified several thousandfold by affi... more Abstract The γ‐aminobutyric acid (GABA) type A receptor was purified several thousandfold by affinity chromatography from rat cerebellum, adult cortex, and neonatal cortex. Competition for the benzodiazepine binding site by CL 218872 indicated that cerebellar receptors were predominantly type I, adult cortical receptors were a mixture of subtypes, and neonatal cortex was enriched in type II receptor. The receptor purified from neonatal cortex contained predominantly a 54‐kilodalton (kDa), β‐subunit‐like protein, whereas receptors from cerebellum and adult cortex contained nearly equal amounts of a 50‐kDa, α‐subunit‐like protein and a 54‐kDa polypeptide. Peptide maps of trypsin‐digested 54‐kDa subunits from cerebellum, adult cortex, and neonatal cortex exhibited very similar profiles, a result indicating considerable homology between these proteins in the receptor subtypes. A 59‐kDa subunit protein was detected in the receptor complex purified from neonatal cortex. Like the 50‐kDa, α‐subunit of the type I receptor, this protein was photolabeled with [3H] flunitrazepam. The photolabeled peptide fragments, produced by trypsin digestion of these α50‐ and α59‐subunits, exhibited the same retention times on reverse‐phase HPLC. A less highly purified GABAA receptor preparation from adult rat spinal cord possessed characteristics that were very similar to those of the receptors purified from neonatal cortex.
Journal of Neurochemistry, May 1, 1993
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](Brain Research, Jun 1, 1975
Biological Psychiatry, 2008
Developmental Brain Research, Jun 1, 1999
Nature Reviews Drug Discovery, Nov 24, 2005
Modulation of N-acetyl-L-aspartyl-L-glutamate peptidase activity with small-molecule inhibitors h... more Modulation of N-acetyl-L-aspartyl-L-glutamate peptidase activity with small-molecule inhibitors holds promise for a wide variety of diseases that involve glutamatergic transmission, and has implications for the diagnosis and therapy of cancer. This new class of compounds, of which at least one has entered clinical trials and proven to be well tolerated, has demonstrated efficacy in experimental models of pain, schizophrenia, amyotrophic lateral sclerosis, traumatic brain injury and, when appropriately functionalized, can image prostate cancer. Further investigation of these promising drug candidates will be needed to bring them to the marketplace. The recent publication of the X-ray crystal structure for the enzymatic target of these compounds should facilitate the development of other new agents with enhanced activity that could improve both the diagnosis and treatment of neurological disorders.
Brain Research, Sep 1, 1987
Journal of Neurochemistry, Oct 1, 1989
Abstract: Antibodies were prepared against a synthetic peptide corresponding to amino acid sequen... more Abstract: Antibodies were prepared against a synthetic peptide corresponding to amino acid sequences 174‐203 of the bovine γ‐aminobutyric acidA (GABAA) receptor α1‐subunit. The antibodies recognized this synthetic α1 ‐peptide, but failed to react with the homologous peptide sequence, 170‐199, of the bovine βl‐subunit. On Western blots, anti‐α1‐subunit antibody recognized a 50‐kilodalton (kDa) protein in affinity‐purified receptor preparations from adult rat cortex and cerebellum. In receptor purified from neonatal cortex, the antiα1‐antibody reacted with 50‐kDa, 53‐54‐kDa, and 59‐kDa proteins. After digestion with endoglycosidase F, these three protein bands retained differing electrophoretic mobilities. The 50‐kDa and 59‐kDa subunits of affinity‐purified neonatal receptor, which were photoaffinity‐labeled with [3H]fluni‐trazepam, were immunoprecipitated to different extents by α‐subunit antibody. These data suggest the existence in GA‐BAA receptor from neonatal cortex of three proteins (50 kDa, 53 kDa, and 59 kDa) which have immunological homology to αl‐subunit of bovine GABAA receptor. The presence of an α‐ and a β‐like subunit with similar mobility on sodium dodecyl sulfate‐polyacrylamide gel electrophoresis may account for the relatively high concentration of protein in the 53‐54‐kDa band which has been observed in receptor purified from neonatal cortex. The presence of multiple α‐like sub‐units may be related to the presence of a relatively high concentration of type IIGABA receptor in this tissue.
Neuropharmacology, Mar 1, 2004
The peptide transmitter N-acetylaspartylglutamate (NAAG) selectively activates the group II metab... more The peptide transmitter N-acetylaspartylglutamate (NAAG) selectively activates the group II metabotropic glutamate receptors. Several reports also suggest that this peptide acts as a partial agonist at N-methyl-D-aspartate (NMDA) receptors but its putative antagonist effects have not been directly tested. To do this, we used whole cell recordings from cerebellar granule cells (CGC) in culture that allow the highest possible resolution of NMDA channel activation. When CGC were activated with equimolar concentrations of NMDA and NAAG, the peptide failed to alter the peak current elicited by NMDA. Very high concentrations of NAAG (100-200 microM) did not significantly reduce the current elicited by 10 microM NMDA or 0.1 microM glutamate, while 400 microM NAAG produced only a very small (less than 15%) reduction in these whole cell currents. Similarly, NAAG (400 microM) failed to significantly alter the average decay time constant or the peak amplitude of NMDA receptor-mediated miniature excitatory post-synaptic currents (mEPSCs). We conclude that high concentrations of the peptide do not exert physiologically relevant antagonist actions on synaptic NMDA receptor activation following vesicular release of glutamate. As an agonist, purified NAAG was found to be at least 10,000-fold less potent than glutamate in increasing "background" current via NMDA receptors on CGC. Inasmuch as it is difficult to confirm that NAAG preparations are completely free from contamination with glutamate at the 0.01% level, the peptide itself appears unlikely to have a direct agonist activity at the NMDA receptor subtypes found in CGC. Recent reports indicate that enhancing the activity of endogenous NAAG may be an important therapeutic approach to excitotoxicity and chronic pain perception. These effects are likely mediated by group II mGluRs, not NMDA receptors.
Brain Research, Jun 1, 1985
Journal of Neurochemistry, Jun 28, 2008
N-Acetylaspartylglutamate (NAAG), a prevalent peptide in the vertebrate nervous system, may be hy... more N-Acetylaspartylglutamate (NAAG), a prevalent peptide in the vertebrate nervous system, may be hydrolyzed by extracellular peptidase activity to produce glutamate and N-acetylaspartate. Hydrolysis can be viewed as both inactivating the peptide after synaptic release and increasing synaptic levels of ambient glutamate. To test the hypothesis that NAAG and the peptidase activity that hydrolyzes it coexist as a unique, two-stage system of chemical neurotransmission, 50 discrete regions of the rat CNS were microdissected for assay. In each microregion, the concentration of NAAG was determined by radioimmunoassay and the peptidase activity was assayed using tritiated peptide as substrate. The NAAG concentration ranged from 2.4 nmol/mg of soluble protein in median eminence to 64 in thoracic spinal cord. Peptidase activity against NAAG ranged from 54 pmol of glutamate produced per milligram of membrane protein per minute in median eminence to 148 in superior colliculus. A linear relationship was observed between NAAG peptidase and NAAG concentration in 46 of the 50 areas, with a slope of 2.26 and a correlation coefficient of 0.45. These data support the hypothesis that hydrolysis of NAAG to glutamate and N-acetylaspartate is a consistent aspect of the physiology and metabolism of this peptide after synaptic release. The ratio of peptide concentration to peptidase activity was > 0.3 in the following four areas: ventrolateral medulla and reticular formation where the peptide is concentrated in axons of passage, thoracic spinal cord, where NAAG is concentrated in ascending sensory tracts as well as motoneuron cell bodies, and ventroposterior thalamic nucleus.
Brain Research, Mar 1, 1987
European Journal of Neuroscience, May 1, 1991
Journal of comparative neurology, Nov 1, 1991
The acidic dipeptide N‐acetylaspartylglutamate (NAAG) was identified immunohistochemically within... more The acidic dipeptide N‐acetylaspartylglutamate (NAAG) was identified immunohistochemically within neurons of the visual pathways of two adult macaque monkeys which had undergone midsagittal sectioning of the optic chiasm 6 or 9 years earlier. In both temporal and nasal retinae, amacrine cells, including some displaced amacrine cells, expressed NAAG immunoreactivity. In temporal but not nasal retina, retinal ganglion cells were stained, as were their dendrites in‐the inner plexiform layer, and their axons in the optic nerve fiber layer. In nasal retina, the ganglion cells had degenerated because they were axotomized by the optic chiasm section. In the target regions of the retinal ganglion cells, the superior colliculus and the lateral geniculate nucleus (LGN), both neuropil and cell bodies were stained. In LGN, staining was confined to layers 2, 3, and 5, that is, to the layers innervated by the intact ipsilateral pathway. Immunoreactivity was also seen in the cells of layers 2, 3A, 4B, 5, and 6 of area 17 and layers 3 and 5 of area 18. The neuropil was stained in all layers of area 17, but more heavily in layers 1, 2, 4B, the bottom of 4Cβ, 5B, and 6B. Within 4C the staining was patchy; in tangential sections there were alternating bands of light and dark label which matched the ocular dominance bands demonstrated by cytochrome oxidase histochemistry in adjacent sections. This banding pattern is consistent with the presence of NAAG in geniculocortical terminals of the intact ipsilateral pathway and the absence of such terminals for the contralateral pathway, which had undergone transneuronal degeneration due to the optic chiasm sectioning. Overall, our results for monkey are very similar to those in cat and suggest that NAAG or a structurally related molecule may have a prominent role in the communication of visual signals at retinal, thalamic, and cortical levels.
Journal of Neurophysiology, 2003
Brain Research, Jul 1, 1988
Neuropeptides, May 1, 1993
Journal of Cell Biology, Jul 1, 1977
Journal of Neurochemistry, Apr 1, 1989
Abstract The γ‐aminobutyric acid (GABA) type A receptor was purified several thousandfold by affi... more Abstract The γ‐aminobutyric acid (GABA) type A receptor was purified several thousandfold by affinity chromatography from rat cerebellum, adult cortex, and neonatal cortex. Competition for the benzodiazepine binding site by CL 218872 indicated that cerebellar receptors were predominantly type I, adult cortical receptors were a mixture of subtypes, and neonatal cortex was enriched in type II receptor. The receptor purified from neonatal cortex contained predominantly a 54‐kilodalton (kDa), β‐subunit‐like protein, whereas receptors from cerebellum and adult cortex contained nearly equal amounts of a 50‐kDa, α‐subunit‐like protein and a 54‐kDa polypeptide. Peptide maps of trypsin‐digested 54‐kDa subunits from cerebellum, adult cortex, and neonatal cortex exhibited very similar profiles, a result indicating considerable homology between these proteins in the receptor subtypes. A 59‐kDa subunit protein was detected in the receptor complex purified from neonatal cortex. Like the 50‐kDa, α‐subunit of the type I receptor, this protein was photolabeled with [3H] flunitrazepam. The photolabeled peptide fragments, produced by trypsin digestion of these α50‐ and α59‐subunits, exhibited the same retention times on reverse‐phase HPLC. A less highly purified GABAA receptor preparation from adult rat spinal cord possessed characteristics that were very similar to those of the receptors purified from neonatal cortex.
Journal of Neurochemistry, May 1, 1993
Brain Research, Jun 1, 1975
Biological Psychiatry, 2008
Developmental Brain Research, Jun 1, 1999
Nature Reviews Drug Discovery, Nov 24, 2005
Modulation of N-acetyl-L-aspartyl-L-glutamate peptidase activity with small-molecule inhibitors h... more Modulation of N-acetyl-L-aspartyl-L-glutamate peptidase activity with small-molecule inhibitors holds promise for a wide variety of diseases that involve glutamatergic transmission, and has implications for the diagnosis and therapy of cancer. This new class of compounds, of which at least one has entered clinical trials and proven to be well tolerated, has demonstrated efficacy in experimental models of pain, schizophrenia, amyotrophic lateral sclerosis, traumatic brain injury and, when appropriately functionalized, can image prostate cancer. Further investigation of these promising drug candidates will be needed to bring them to the marketplace. The recent publication of the X-ray crystal structure for the enzymatic target of these compounds should facilitate the development of other new agents with enhanced activity that could improve both the diagnosis and treatment of neurological disorders.
Brain Research, Sep 1, 1987
Journal of Neurochemistry, Oct 1, 1989
Abstract: Antibodies were prepared against a synthetic peptide corresponding to amino acid sequen... more Abstract: Antibodies were prepared against a synthetic peptide corresponding to amino acid sequences 174‐203 of the bovine γ‐aminobutyric acidA (GABAA) receptor α1‐subunit. The antibodies recognized this synthetic α1 ‐peptide, but failed to react with the homologous peptide sequence, 170‐199, of the bovine βl‐subunit. On Western blots, anti‐α1‐subunit antibody recognized a 50‐kilodalton (kDa) protein in affinity‐purified receptor preparations from adult rat cortex and cerebellum. In receptor purified from neonatal cortex, the antiα1‐antibody reacted with 50‐kDa, 53‐54‐kDa, and 59‐kDa proteins. After digestion with endoglycosidase F, these three protein bands retained differing electrophoretic mobilities. The 50‐kDa and 59‐kDa subunits of affinity‐purified neonatal receptor, which were photoaffinity‐labeled with [3H]fluni‐trazepam, were immunoprecipitated to different extents by α‐subunit antibody. These data suggest the existence in GA‐BAA receptor from neonatal cortex of three proteins (50 kDa, 53 kDa, and 59 kDa) which have immunological homology to αl‐subunit of bovine GABAA receptor. The presence of an α‐ and a β‐like subunit with similar mobility on sodium dodecyl sulfate‐polyacrylamide gel electrophoresis may account for the relatively high concentration of protein in the 53‐54‐kDa band which has been observed in receptor purified from neonatal cortex. The presence of multiple α‐like sub‐units may be related to the presence of a relatively high concentration of type IIGABA receptor in this tissue.
Neuropharmacology, Mar 1, 2004
The peptide transmitter N-acetylaspartylglutamate (NAAG) selectively activates the group II metab... more The peptide transmitter N-acetylaspartylglutamate (NAAG) selectively activates the group II metabotropic glutamate receptors. Several reports also suggest that this peptide acts as a partial agonist at N-methyl-D-aspartate (NMDA) receptors but its putative antagonist effects have not been directly tested. To do this, we used whole cell recordings from cerebellar granule cells (CGC) in culture that allow the highest possible resolution of NMDA channel activation. When CGC were activated with equimolar concentrations of NMDA and NAAG, the peptide failed to alter the peak current elicited by NMDA. Very high concentrations of NAAG (100-200 microM) did not significantly reduce the current elicited by 10 microM NMDA or 0.1 microM glutamate, while 400 microM NAAG produced only a very small (less than 15%) reduction in these whole cell currents. Similarly, NAAG (400 microM) failed to significantly alter the average decay time constant or the peak amplitude of NMDA receptor-mediated miniature excitatory post-synaptic currents (mEPSCs). We conclude that high concentrations of the peptide do not exert physiologically relevant antagonist actions on synaptic NMDA receptor activation following vesicular release of glutamate. As an agonist, purified NAAG was found to be at least 10,000-fold less potent than glutamate in increasing "background" current via NMDA receptors on CGC. Inasmuch as it is difficult to confirm that NAAG preparations are completely free from contamination with glutamate at the 0.01% level, the peptide itself appears unlikely to have a direct agonist activity at the NMDA receptor subtypes found in CGC. Recent reports indicate that enhancing the activity of endogenous NAAG may be an important therapeutic approach to excitotoxicity and chronic pain perception. These effects are likely mediated by group II mGluRs, not NMDA receptors.
Brain Research, Jun 1, 1985
Journal of Neurochemistry, Jun 28, 2008
N-Acetylaspartylglutamate (NAAG), a prevalent peptide in the vertebrate nervous system, may be hy... more N-Acetylaspartylglutamate (NAAG), a prevalent peptide in the vertebrate nervous system, may be hydrolyzed by extracellular peptidase activity to produce glutamate and N-acetylaspartate. Hydrolysis can be viewed as both inactivating the peptide after synaptic release and increasing synaptic levels of ambient glutamate. To test the hypothesis that NAAG and the peptidase activity that hydrolyzes it coexist as a unique, two-stage system of chemical neurotransmission, 50 discrete regions of the rat CNS were microdissected for assay. In each microregion, the concentration of NAAG was determined by radioimmunoassay and the peptidase activity was assayed using tritiated peptide as substrate. The NAAG concentration ranged from 2.4 nmol/mg of soluble protein in median eminence to 64 in thoracic spinal cord. Peptidase activity against NAAG ranged from 54 pmol of glutamate produced per milligram of membrane protein per minute in median eminence to 148 in superior colliculus. A linear relationship was observed between NAAG peptidase and NAAG concentration in 46 of the 50 areas, with a slope of 2.26 and a correlation coefficient of 0.45. These data support the hypothesis that hydrolysis of NAAG to glutamate and N-acetylaspartate is a consistent aspect of the physiology and metabolism of this peptide after synaptic release. The ratio of peptide concentration to peptidase activity was > 0.3 in the following four areas: ventrolateral medulla and reticular formation where the peptide is concentrated in axons of passage, thoracic spinal cord, where NAAG is concentrated in ascending sensory tracts as well as motoneuron cell bodies, and ventroposterior thalamic nucleus.