Utilization of 3-hydroxybutyrate by chick cerebral hemispheres during postnatal maturation
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Newly hatched chicks utilize 3-hydroxybutyrate for brain development, converting it into crucial amino acids like glutamate. This ketone body is vital for early brain maturation in birds.
Area of Science:
- Neuroscience
- Biochemistry
- Developmental Biology
Background:
- The developing brain's energy metabolism shifts after hatching.
- Ketone bodies, like 3-hydroxybutyrate, are alternative energy sources.
Purpose of the Study:
- To investigate the role of 3-hydroxybutyrate in chick telencephalon maturation.
- To compare its utilization in newly hatched versus older chicks.
Main Methods:
- Measured blood concentrations and cerebral uptake of 3-hydroxybutyrate.
- Assessed the incorporation of labeled 3-hydroxybutyrate into amino acids in brain slices and after injection.
Main Results:
- Newly hatched chicks have higher blood 3-hydroxybutyrate levels and greater brain uptake.
- Brain slices and injected chicks showed increased labeling of dicarboxylic amino acids from 3-hydroxybutyrate, especially in younger birds.
- 3-hydroxybutyrate efficiently contributes to glutamate biosynthesis in the young chick brain.
Conclusions:
- 3-hydroxybutyrate serves as a significant precursor for dicarboxylic amino acid synthesis, particularly glutamate, in the post-hatching chick brain.
- This highlights the importance of 3-hydroxybutyrate in early brain development, similar to glucose's role.
Abstract:
1. The utilization of 3-hydroxybutyrate has been studied in the chick telencephalon during its post-hatching maturation. 2. In the 1-day-old chick the blood concentration of 3-hydroxybutyrate appears to be relatively high and its value is 5 times that estimated in the 4- and 30-day-old chicks. 3. The determination of the cerebral arteriovenous differences of 3-hydroxybutyrate shows that the brain of the newly-hatched chick takes up 3 times more actively this ketone body than the brain of the 4-day-old bird does. 4. During incubation in a non-oxygenated and an oxygenated physiological medium, in the presence of 3-hydroxy [3-14C]butyrate, the specific radioactivity of the dicarboxylic amino acids in the 1-day-old chick brain slices is higher than in those of the 30-day-old chick, particularly in the oxygenated medium. 5. Thirty minutes after a subcutaneous injection of 3-hydroxy [3-14C]butyrate, the specific radioactivity of the dicarboxylic amino acids in the 1-day-old chick telencephalon is 3-4 times higher than that in the 4- and 30-day-old chick. 6. In conclusion, in the brain of the newly hatched chick, 3-hydroxybutyrate is an efficient precursor in the biosynthesis of dicarboxylic amino acids, particularly glutamate, and, as glucose, it is metabolically related to the "large compartment" of glutamate. 7. These results have been discussed comparatively to those previously obtained in the developing rodent brain.