Distribution of Serine Hydroxymethyltransferase and Glycine Transaminase in Several Areas of the Central Nervous System of the Rat

Daly, Edward; Aprison, M. H.

doi:10.1111/j.1471-4159.1974.tb04312.x

Cited by 57 publications

(41 citation statements)

References 32 publications

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“…It is of interest to note that the P had a larger percentage of SHMT activity than of MAO activitylin all regions studied. However, when the distribution of LDH (a cytoplasmic enzyme) was determined,it was found to be markedly di~ferent from that noted for SHMT and MAO (Daly and Aprison, 1974a). Thus, these data support the fact that SHMT is mainly, if not exclusively, a particulate enzyme in these areas of the CNS.…”

Section: Enzyme Studiessupporting

confidence: 57%

“…These investigators also found that SHMT is a mitochondrial enzyme. Daly and Aprison (1974a) found that a good correlation exists between SHMT activity/mg-protein and glycine levels when the cerebellar data were not considered (r = 0.997; P<0.05). However, when the SHMT activity per relative number of mitochondria (SHMT/SDH) is calculated (Gregson & Williams, 1969) excellent correlation with glycine levels was found for all five areas studied.…”

Section: Enzyme Studiesmentioning

confidence: 79%

“…Studies on the regional distribution of SHMT activity, GT activity, SDH activity and glycine content by Daly and Aprison (1974a) indicate that these parameters varied di~~erently among the ~ive di~~erent areas o~ brain and spinal cord (TABLE VI). The SHMT activity was highest in the spinal cord and medulla-pons, followed in order to decreasing activity by the cerebellum, midbrain and telencephalon, whereas for the GT activities, the value for the spinal cord was lowest and those of the ~our brain areas were the same.…”

Section: Enzyme Studiesmentioning

confidence: 96%

See 2 more Smart Citations

Glycine: Inhibition from the Sacrum to the Medulla

Aprison

Nadi

1978

Amino Acids as Chemical Transmitters

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Section: Enzyme Studiessupporting

confidence: 57%

Section: Enzyme Studiesmentioning

confidence: 79%

Section: Enzyme Studiesmentioning

confidence: 96%

See 1 more Smart Citation

Glycine: Inhibition from the Sacrum to the Medulla

Aprison

Nadi

1978

Amino Acids as Chemical Transmitters

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“…In the case of incubation with aminopterin, the preincubation medium already contained 100 µM aminopterin. brain (Daly and Aprison, 1974;Rassin and Gaull, 1975). We have detected both enzymatic activities in astrogliarich primary cultures and therefore propose that glycine is degraded by the cultured cells in the way that one molecule of glycine is cleaved by the GCS, yielding one C1 unit in the form of N 5 ,N 10 -methylenetetrahydrofolate.…”

Section: Discussionmentioning

confidence: 90%

Rapid uptake and degradation of glycine by astroglial cells in culture: Synthesis and release of serine and lactate

Verleysdonk

Martin

Willker

et al. 1999

Glia

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Free glycine is known to have vital functions in the mammalian brain, where it serves mainly as both neurotransmitter and neuromodulator. Despite its importance, little is known about the metabolic pathways of glycine synthesis and degradation in the central nervous system. In this study, the pathway of glycine metabolism in astroglia-rich primary cultures from rat brain was examined. The cells were allowed to degrade glycine in the presence of [U-14 C]glycine, [U-13 C]glycine or [ 15 N]glycine. The resulting intra-and extracellular metabolites were analyzed both by high-performance liquid chromatography and by 13 C/ 15 N nuclear magnetic resonance spectroscopy. Glycine was rapidly consumed in a process obeying first-order kinetics. The initial glycine consumption rate was 0.47 nmol per mg protein. The half-life of glycine radiolabel in the incubation medium was shorter than that of glycine mass. This suggests that glycine is produced from endogenous sources and released simultaneously with glycine uptake and metabolism. As the main metabolites of the glycine carbon skeleton in astroglia-rich primary cultures from rat brain, serine and lactate were released during glycine consumption. The main metabolite containing the glycine amino nitrogen was glutamine. To establish a metabolic pathway from glycine to serine in neural tissue, homogenates of rat brain and of neural primary cultures were assayed for their content of serine hydroxymethyltransferase (SHMT) and glycine cleavage system (GCS). SHMT activity was present in homogenates of rat brain as well as of astroglia-rich and neuron-rich primary cultures, whereas GCS activity was detectable only in homogenates of rat brain and astroglia-rich primary culture. Of the two known SHMT isoenzymes, only the mitochondrial form was found in rat brain homogenate. It is proposed that, in neural tissue, glycine is metabolized by the combined action of SHMT and the GCS. Owing to the absence of the GCS from neurons, astrocytes appear to be the only site of this part of glycine metabolism in brain. However, neurons are able to utilize as energy source the lactate formed by astroglial cells in this metabolic pathway.

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“…At present we cannot resolve these suppositions. Finally, serine has been posited as the immediate precursor to glycine based on brain (Daly and Aprison, 1974) and retinal biochemistry (Dasgupta and Narayanaswami, 1982), and we presumed that, like elevated glutamate levels in GABAergic neurons, we might observe a concordance between enriched serine signals and G+ cells. However, no cell-specific serine enrichment is evident in the goldfish retina.…”

Section: Additional Amino Acid Patternsmentioning

confidence: 99%

Pattern recognition of amino acid signatures in retinal neurons

1995

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Pattern recognition of amino acid signals partitions the cells of the goldfish retina into nine statistically unique biochemical theme classes and permits a first-order chemical mapping of virtually all cellular space. Photoreceptors, bipolar cells, and ganglion cells display a set of unique, nominally glutamatergic type E1, E1+E2, and E4 signatures, respectively. All horizontal cells are assignable to a GABAergic gamma 2 class or a non-GABAergic class with a glutamate-rich E3 signature. The amacrine cell layer is largely a mixture of (1) a taurine-dominated T1 Muller's cell signature and (2) GABAergic gamma 1, glycinergic G1, and dual glycinergic/GABAergic G gamma 1 amacrine cell signatures. Several major conclusions emerge from this work. (1) Glutamatergic, GABAergic, and glycinergic neural signatures and glial signatures account for over 99% of the cellular space in the retina. (2) All known neurons in the goldfish retina are associated with a set of conventional nonpeptide neurotransmitters. (3) Multiple forms of metabolic profiles are associated with a single nominal neurotransmitter category. (4) Glutamate and aspartate contents exhibit overlapping distributions and are not adequate univariate probes for identifying cell classes. (5) Signatures can serve as quantitative measures of cell state.

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Distribution of Serine Hydroxymethyltransferase and Glycine Transaminase in Several Areas of the Central Nervous System of the Rat

Cited by 57 publications

References 32 publications

Glycine: Inhibition from the Sacrum to the Medulla

Glycine: Inhibition from the Sacrum to the Medulla

Rapid uptake and degradation of glycine by astroglial cells in culture: Synthesis and release of serine and lactate

Pattern recognition of amino acid signatures in retinal neurons

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