Changes with aging in the levels of amino acids in rat CNS structural elements II. Taurine and small neutral amino acids

Banay‐Schwartz, M.; Lajtha, Ábel; Palkovits, Miklós

doi:10.1007/bf00964919

Cited by 99 publications

(48 citation statements)

References 21 publications

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“…The brain amino acid concentration of the control group re ceiving a 17% protein diet was in agreement with other data [I, [14][15][16], Taurine, lysine and tryptophan concentrations did not change in brain tissue by increasing the di etary protein content. Glutamic acid and glu tamine concentrations increased in all groups, particularly in the rats on the low protein diet.…”

Section: Plasma Liver and Brain Amino Acidsupporting

confidence: 80%

Effect of Different Protein Diets on the Distribution of Amino Acids in Plasma, Liver and Brain in the Rat

et al. 1992

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The distribution of amino acids between plasma, liver and brain was studied in adult male rats, fed a diet containing 8.7, 17 (control animals), 32 and 51 % of protein during 15 days. The caloric intake was nearly equal in all groups. The highest food intake was observed in the animals on the low protein diet. Changes in plasma amino acids were variable. In contrast to the behavior of most amino acids in plasma, the branched chain amino acids were highest in the animals fed the 51 % protein diet. Despite the low protein intake in the animals fed a 8.7 % protein diet, the concentration of serine, glutamic acid, glutamine, glycine, alanine, methionine, isoleucine, leucine, phenylalanine and ornithine were significantly higher compared to control animals, whereas in those receiving a high protein diet, valine, leucine, tyrosine, tryptophan and histidine increased in relation to the increased protein and amino acid intake. The plasma amino acid patterns are not greatly influenced by the amino acid distribution in the food and the amount ingested. Alanine aminotransferase, aspartate aminotransferase, glutamate dehydrogenase and cholinesterase showed a two- to fivefold increased activity in the liver of animals consuming a high protein diet. In the brain, the concentration of valine, leucine, isoleucine, phenylalanine and tyrosine in animals receiving the low protein diet was higher than in controls and increased further with increasing protein content of the diet. Glutamine was increased in all dietary groups. The predicted influx of amino acids showed increasing influx rates in dependence of the plasma amino acid concentration. The entry of tyrosine and tryptophan and their brain concentration was inversely proportional to the protein content of the diet. In the present study which considers long-term adaptation to an increasing protein and amino acid intake in comparison to a balanced control protein diet, the levels of the indispensable amino acids were maintained within narrow limits in the brain and liver. The results indicate that inspite of a variable protein intake, the body tends to keep organ amino acids in relatively narrow limits favoring in this way amino acid homeostasis.

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Section: Plasma Liver and Brain Amino Acidsupporting

confidence: 80%

Effect of Different Protein Diets on the Distribution of Amino Acids in Plasma, Liver and Brain in the Rat

et al. 1992

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“…Altered inputs onto fusiform cells from these inhibitory neurons would not be expected to significantly alter fusiform spontaneous rates. Previous DCN aging studies described decreased glycine levels, decreased strychnine binding (especially in the fusiform layer), and a loss of glycine immunoreactivity in cells at the junction between the deep and fusiform-cell layers of the cochlear nucleus (Banay-Schwartz et al, 1989;Willott et al, 1997;Milbrandt et al, 2000;Caspary et al, 2001). The subunit makeup of the glycine receptor showed age-related changes, in both the DCN and AVCN, that could account for functional changes observed in the present study (Krenning et al, 1998;Caspary et al, 2002).…”

Section: Discussionmentioning

confidence: 91%

“…Age-related loss of markers for inhibitory amino acids has also been described for the auditory midbrain. The inferior colliculus (IC) shows significant age-related changes related to GABA neurotransmission in rats (Banay-Schwartz et al, 1989;Caspary et al, 1990Caspary et al, , 1995Gutierrez et al, 1994;Milbrandt et al, 1994;Raza et al, 1994) and the loss of GABAimmunoreactive synaptic endings. Postmortem human studies of the cortex and IC are less clear.…”

Section: Discussionmentioning

confidence: 99%

Age-Related Changes in the Inhibitory Response Properties of Dorsal Cochlear Nucleus Output Neurons: Role of Inhibitory Inputs

Caspary

Schatteman²,

Hughes³

2005

J. Neurosci.

161

114

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Age-related hearing loss frequently results in a loss in the ability to discriminate speech signals, especially in noise. This is attributable, in part, to a loss in temporal resolving power and ability to adjust dynamic range. Circuits in the adult dorsal cochlear nucleus (DCN) have been shown to preserve signal in background noise. Fusiform cells, major DCN output neurons, receive focused glycinergic inputs from tonotopically aligned vertical cells that also project to the ventral cochlear nucleus. Glycine-mediated inhibition onto fusiform cells results in decreased tone-evoked activity as intensity is increased at frequencies adjacent to characteristic frequency (CF). DCN output is thus shaped by glycinergic inhibition, which can be readily assessed in recordings from fusiform cells. Previous DCN studies suggest an age-related loss of markers for glycinergic neurotransmission. The present study postulated that response properties of aged fusiform cells would show a loss of inhibition, resembling conditions observed with glycine receptor blockade. The functional impact of aging was examined by comparing response properties from units meeting fusiform-cell criteria in young and aged rats. Fusiform cells in aged animals displayed significantly higher maximum discharge rates to CF tones than those recorded from young-adult animals. Fusiform cells of aged rats displayed significantly fewer nonmonotonic CF rate-level functions and an age-related change in temporal response properties. These findings are consistent with an age-related loss of glycinergic input, likely from vertical cells, and with findings from other sensory aging studies suggesting a selective age-related decrement in inhibitory amino acid neurotransmitter function.

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“…Peripheral auditory changes include a sloping low-frequency loss of outer hair cells and a small loss of apical and basal inner hair cells (for review, see Willott et al, 1991;Saitoh et al, 1994;Gratton et al, 1996Gratton et al, , 1997Spongr et al, 1997;Ingham et al, 1999;Tang et al, 2014) accompanied by auditory nerve fiber loss (Keithley et al, 1989(Keithley et al, , 1992Dazert et al, 1996;Schmiedt et al, 1996). Parallel central aging effects include a net down-regulation of glycinergic and GABAergic inhibition in the cochlear nucleus (Banay-Schwartz et al, 1989b;Krenning et al, 1998;, inferior colliculus (Banay-Schwartz et al, 1989a,b;Caspary et al, 1990;Gutierrez et al, 1994;Milbrandt et al, 1994Milbrandt et al, , 1996, MGB (Richardson et al, 2013a), and auditory cortex Stebbings et al, 2016). This CANS loss of inhibition at least partially subserves the age-related loss of accurate temporal processing seen in older humans (Harris et al, 2012;Mattys and Scharenborg, 2014).…”

Section: Changes Of Bottom-up Processing With Agingmentioning

confidence: 99%

Responses to Predictable versus Random Temporally Complex Stimuli from Single Units in Auditory Thalamus: Impact of Aging and Anesthesia

2016

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Human aging studies suggest that an increased use of top-down knowledge-based resources would compensate for degraded upstream acoustic information to accurately identify important temporally rich signals. Sinusoidal amplitude-modulated (SAM) stimuli have been used to mimic the fast-changing temporal features in speech and species-specific vocalizations. Single units were recorded from auditory thalamus [medial geniculate body (MGB)] of young awake, aged awake, young anesthetized, and aged anesthetized rats. SAM stimuli were modulated between 2 and 1024 Hz with the modulation frequency ( fm) changed randomly (RAN) across trials or sequentially (SEQ) after several repeated trials. Units were found to be RAN-preferring, SEQ-preferring, or nonselective based on total firing rate. Significant anesthesia and age effects were found. The majority (86%) of young anesthetized units preferred RAN SAM stimuli; significantly fewer young awake units (51%, p Ͻ 0.0001) preferred RAN SAM signals with 16% preferring SEQ SAM. Compared with young awake units, there was a significant increase of aged awake units preferring SEQ SAM (30%, p Ͻ 0.05). We examined RAN versus SEQ differences across fms by measuring selective fm areas under the rate modulation transfer function curve. The largest age-related differences from awake animals were found for mid-to-high fms in MGB units, with young units preferring RAN SAM while aged units showed a greater preference for SEQ-presented SAM. Together, these findings suggest that aged MGB units/animals employ increased top-down mediated stimulus context to enhance processing of "expected" temporally rich stimuli, especially at more challenging higher fms.

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Changes with aging in the levels of amino acids in rat CNS structural elements II. Taurine and small neutral amino acids

Cited by 99 publications

References 21 publications

Effect of Different Protein Diets on the Distribution of Amino Acids in Plasma, Liver and Brain in the Rat

Effect of Different Protein Diets on the Distribution of Amino Acids in Plasma, Liver and Brain in the Rat

Age-Related Changes in the Inhibitory Response Properties of Dorsal Cochlear Nucleus Output Neurons: Role of Inhibitory Inputs

Responses to Predictable versus Random Temporally Complex Stimuli from Single Units in Auditory Thalamus: Impact of Aging and Anesthesia

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