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Rates of local cerebral protein synthesis in the rat during normal postnatal development
1Laboratory of Cerebral Metabolism, National Institutes of Mental Health, Bethesda, Maryland 20892.
Insights
Protein synthesis in the developing rat brain shows regional variations. Cerebral leucine incorporation into protein (lCPSleu) is highest in early development, decreasing with age, except in specific hypothalamic nuclei.
Area of Science:
- Neuroscience
- Developmental Biology
- Biochemistry
Background:
- Protein synthesis and degradation are fundamental processes in brain development.
- Understanding the dynamics of amino acid recycling is crucial for assessing protein synthesis rates.
- Leucine is a key amino acid for protein synthesis.
Purpose of the Study:
- To measure the recycling of leucine from protein breakdown into the protein synthesis precursor pool in the rat brain.
- To calculate age-specific regional rates of cerebral leucine incorporation into protein (lCPSleu).
- To investigate developmental changes in protein synthesis across 44 brain regions.
Main Methods:
- Measurement of leucine recycling from protein breakdown at different postnatal ages in rats.
- Calculation of regional cerebral leucine incorporation into protein (lCPSleu) using age-specific values.
- Analysis of protein synthesis rates in 44 distinct brain regions and the whole brain.
Main Results:
- Protein degradation contributes a larger fraction to the precursor leucine pool in young rats compared to adults.
- Cerebral leucine incorporation into protein (lCPSleu) peaked at 10 days in the whole brain and most regions, then declined with age.
- Specific regions like the hypothalamus showed increased lCPSleu with age, while white matter peaks correlated with myelination timing.
Conclusions:
- Protein synthesis rates in the rat brain undergo significant developmental changes, varying by region.
- The balance between protein synthesis and degradation shifts during postnatal development.
- Regional differences in lCPSleu highlight the diverse developmental trajectories of brain structures.
Abstract:
The degree of recycling of leucine derived from protein breakdown into the precursor pool for protein synthesis was measured in rat brain at different postnatal ages, and age-specific values were used in the calculation of regional (local) rates of cerebral leucine incorporation into protein (lCPSleu) in 44 brain regions and the brain as a whole. Early in development, a greater fraction of the precursor leucine pool is derived from protein breakdown, indicating that protein degradation is higher in young rats compared with adults. In whole brain and in most regions, values for lCPSleu were highest at 10 days and gradually decreased with age. By 60 days of age, values in cortex were approximately 60% of those at 10 days of age. In the paraventricular and supraoptic nuclei of the hypothalamus, however, lCPSleu increased during development, reaching peak values in adults. In white matter of the cerebellum and the cerebrum, peaks of lCPSleu were reached at 14 and 21 days, respectively, approximately at the times of maximum rates of myelination.