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Acidic amino acid accumulation by rat choroid plexus during development
H al-Sarraf1, J E Preston, M B Segal
1Sherrington School of Physiology, UMDS, St. Thomas' Hospital, London, UK. hameed@hsccmail.kuniv.edu.kw
Brain Research. Developmental Brain Research
|August 18, 1997
Summary
Acidic amino acid uptake by rat choroid plexus decreases with age. Both blood and CSF uptake of aspartate and glutamate show developmental decline, indicating maturation of transport mechanisms.
Area of Science:
- Neuroscience
- Developmental Biology
- Biochemistry
Background:
- The choroid plexus is crucial for regulating the cerebrospinal fluid (CSF) composition.
- Acidic amino acids like aspartate and glutamate play vital roles in neurotransmission.
- Understanding their transport across the blood-CSF barrier is essential for brain health.
Purpose of the Study:
- To investigate the developmental changes in acidic amino acid accumulation by the choroid plexus.
- To compare uptake from both blood and CSF sides of the choroid plexus.
- To characterize the transport kinetics and specificity of these amino acids.
Main Methods:
- Utilized bilateral in situ brain perfusion in rats of various ages (1 week to adult).
- Measured uptake of 14C-labeled aspartate, glutamate, and NMDA, with 3H-mannitol as a control.
- Employed ventriculo-cisternal perfusion to assess uptake from the CSF side.
Main Results:
- Uptake of [14C]aspartate and [14C]glutamate significantly declined with age from both blood and CSF sides.
- [14C]NMDA showed no significant uptake at any age.
- Transport kinetics (K(m)) for aspartate and glutamate decreased with development, indicating reduced transport capacity.
Conclusions:
- Choroid plexus transport of acidic amino acids is developmentally regulated, decreasing significantly from neonate to adult.
- The transport mechanisms are saturable, stereospecific, and shared by aspartate and glutamate.
- These findings highlight the maturation of the blood-CSF barrier's amino acid handling capacity.