Cerebral leucine uptake and protein synthesis in the  near-term ovine fetus: relation to fetal behavioral state

Czikk, Marie J.; Sweeley, John; Homan, Jacobus; Milley, J. Ross; Richardson, Bryan

doi:10.1152/ajpregu.00190.2002

Cited by 28 publications

(25 citation statements)

References 22 publications

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“…As such, we found no evidence of a differential effect of increases versus decreases in circulating amino acids as maintained over 2-4 h on cerebral protein synthesis in the near-term ovine fetus. Of note, the FSR MAX and FS-R MIN values reported herein for the cerebral cortex are somewhat higher than those reported by Schaefer and Krishnamurti [1] for animals at ϳ 130 days' gestation at ϳ 37 and 14%/day, respectively, and by Czikk et al [3] for animals at ϳ 135 days' gestation at ϳ 20 and 16%/day, respectively. This may relate to a developmental decrease in cerebral protein synthesis/degradation as seen in rodents during early brain development [5] and is consistent with the higher cerebral FSR values we have reported for the preterm ovine fetus [24] .…”

Section: Discussioncontrasting

confidence: 69%

“…13 C]-leucine enrichment were modified from those reported by Horber et al [23] and Czikk et al [3] , as we have previously described [24] .…”

Section: Tissue Leucine Content Enrichment and Protein Synthesismentioning

confidence: 99%

“…It can be calculated for each brain region using respective MPE PB and MPE IF or MPE P values, depending on which is considered to be more representative of the precursor pool, and the total infusion time (days) in the following formulae [3] :…”

Section: Tissue Leucine Content Enrichment and Protein Synthesismentioning

confidence: 99%

“…Protein synthesis during brain growth and development has been studied in the near-term ovine fetus [1][2][3] as well as postnatally in sheep [2] , and shown to be high (upwards of 40%/day) in protein fractional synthetic rates (FSR), i.e. the percentage of brain protein that is newly synthesized per day.…”

Section: Introductionmentioning

confidence: 99%

“…Postnatal studies in rats have also shown high rates of brain protein synthesis during early development, with peak values occurring shortly after birth and gradually decreasing thereafter [4,5] . While high rates of cerebral protein synthesis are thus evident during early life in both sheep and rats in support of the brain's growth and development, these rates are considerably greater than the anticipated protein accretion, indi-cating that protein degradation must also play an important role in the growth and development of the brain [3,5] .…”

Section: Introductionmentioning

confidence: 99%

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Cerebral Protein Synthesis in the Ovine Fetus Near Term with Amino Acid Infusion and Insulin-Induced Hypoaminoacidemia

MacLachlan¹,

McCallum²,

Smith

et al. 2010

Neonatology

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Background: Studies during early development have shown that the precursor availability of amino acids directly affects protein synthesis both at the whole-body level and for select organ tissues, although this has not been studied for the brain. Objective: We utilized a mixed amino acid infusate and an insulin euglycemic clamp technique in the ovine fetus near term, with increases and decreases in circulating amino acid levels of ∼30 to 40% on average, and determined the impact on cerebral protein synthesis. Methods: Fetal sheep received a 6-hour infusion of Primene® 10% (amino acid infusate group) or a co-infusion of insulin and 10% dextrose (insulin/dextrose infusate group) together with a continuous infusion of L-[1-¹³C]-leucine. Measurements were obtained for fetal plasma leucine enrichment at steady-state and brain tissue intracellular free and protein-bound leucine enrichment at necropsy, followed by the determination of cerebral protein fractional synthetic rates (FSR). Results: Protein FSR for the cerebral cortex averaged ∼58 and ∼39%/day when using the intracellular free and plasma enrichment values for the precursor pool measurements, respectively, providing for maximal and minimal FSR values, and with little difference between the amino acid and insulin/dextrose groups, although significantly higher than respective values for the cerebellum. Conclusion: Accordingly, there was no evidence of a differential effect of increases versus decreases in circulating amino acids on cerebral protein synthesis as studied, which may be attributed to the saturable nature of the blood-brain barrier transporters for amino acids.

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Section: Discussioncontrasting

confidence: 69%

“…13 C]-leucine enrichment were modified from those reported by Horber et al [23] and Czikk et al [3] , as we have previously described [24] .…”

Section: Tissue Leucine Content Enrichment and Protein Synthesismentioning

confidence: 99%

Section: Tissue Leucine Content Enrichment and Protein Synthesismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cerebral Protein Synthesis in the Ovine Fetus Near Term with Amino Acid Infusion and Insulin-Induced Hypoaminoacidemia

MacLachlan¹,

McCallum²,

Smith

et al. 2010

Neonatology

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Neonatal eyelid conditioning during sleep

Tarullo

Isler

Condon

et al. 2016

Developmental Psychobiology

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Using an eyelid conditioning paradigm modeled after that developed by Little, Lipsitt, and Rovee-Collier (1984), Fifer et al. (2010) demonstrated that newborn infants learn during sleep. This study examined the role of sleep state in neonatal learning. We recorded electroencephalogram (EEG), respiratory, and cardiovascular activity from sleeping full term newborn infants during delay eyelid conditioning. In the experimental group (n = 21), a tone was paired with an air puff to the eye. Consistent with Fifer et al. (2010), newborn infants reliably learned during sleep. The experimental group more than doubled EMR rates to a tone alone, while a control group (n = 17) presented with unpaired tones and puffs maintained low EMR rates. Infant learners were more likely to produce a conditioned EMR during quiet sleep compared to active sleep. Understanding the influence of sleep state on conditioned responses will inform the potential use of eyelid conditioning for early screening.

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Sleep and infant learning

Tarullo

Balsam

Fifer

2011

Infant and Child Development

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Human neonates spend the majority of their time sleeping. Despite the limited waking hours available for environmental exploration, the first few months of life are a time of rapid learning about the environment. The organization of neonate sleep differs qualitatively from adult sleep, and the unique characteristics of neonatal sleep may promote learning. Sleep contributes to infant learning in multiple ways. First, sleep facilitates neural maturation, thereby preparing infants to process and explore the environment in increasingly sophisticated ways. Second, sleep plays a role in memory consolidation of material presented while the infant was awake. Finally, emerging evidence indicates that infants process sensory stimuli and learn about contingencies in their environment even while asleep. As infants make the transition from reflexive to cortically mediated control, learned responses to physiological challenges during sleep may be critical adaptations to promote infant survival.

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Cerebral leucine uptake and protein synthesis in the near-term ovine fetus: relation to fetal behavioral state

Cited by 28 publications

References 22 publications

Cerebral Protein Synthesis in the Ovine Fetus Near Term with Amino Acid Infusion and Insulin-Induced Hypoaminoacidemia

Cerebral Protein Synthesis in the Ovine Fetus Near Term with Amino Acid Infusion and Insulin-Induced Hypoaminoacidemia

Neonatal eyelid conditioning during sleep

Sleep and infant learning

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