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Change of zinc distribution in rat brain with increasing age
J Sawashita1, A Takeda, S Okada
1Department of Radiobiochemistry, School of Pharmaceutical Sciences, University of Shizuoka, Japan.
Insights
Brain zinc accumulation is crucial for development and function. Neonatal rats show higher zinc uptake in the cerebellum, while adults exhibit higher concentrations in the hippocampus.
Area of Science:
- Neuroscience
- Developmental Biology
- Trace Element Research
Background:
- Zinc (Zn) plays a vital role in brain development and function.
- Understanding Zn accumulation patterns across different brain regions and ages is essential.
Purpose of the Study:
- To investigate the significance of zinc accumulation in the rat brain during development and aging.
- To compare Zn distribution in neonatal versus adult rat brains.
Main Methods:
- Analysis of endogenous zinc concentrations in rat brain tissues at various ages (neonatal to adult).
- Radiotracer study using 65ZnCl2 injection in neonatal (5-day-old) and adult (48-week-old) rats.
- Quantification of 65Zn distribution across different brain regions (cerebral hemisphere, cerebellum, cerebral cortex, hippocampus formation).
Main Results:
- Cerebral hemisphere Zn concentration was low in neonatal rats (1-11 days).
- Cerebellar Zn concentration increased post-birth, plateauing around 11 days.
- Adult (48-week-old) rat brains showed higher Zn concentrations in the cerebral cortex and hippocampus compared to the neonatal cerebral hemisphere.
- Neonatal rats exhibited higher 65Zn distribution overall compared to adult rats.
- In neonates, 65Zn concentrated highest in the cerebellum, then hippocampus; in adults, it concentrated in the hippocampus (CA3 and dentate gyrus).
Conclusions:
- The cerebellum shows high zinc demand during rapid postnatal development.
- Increasing zinc concentrations with age suggest roles in neuromodulation and ongoing brain maturation.
- Differential zinc accumulation patterns highlight region-specific developmental trajectories and functional requirements.
Abstract:
Zinc (Zn) accumulation in the brain of rats of various ages was studied to look into the significance of Zn for the development and function of the brain. The Zn concentration of the cerebral hemisphere was relatively low in 1- to 11-day-old rats. The Zn concentration of the cerebellum gradually increased after birth and reached nearly a plateau at 11 days old. At 48 weeks old, the Zn concentrations of the cerebral cortex and hippocampus formation were approximately twice that of the cerebral hemisphere at the early stage after birth and significantly higher than that of the cerebellum. When 65ZnCl2 was injected into two groups of rats at 5 days and 48 weeks old for comparison, 65Zn distribution in the brain of the former group was higher than that of the latter. In the neonatal rats, the highest concentration of 65Zn was found in the cerebellum, followed by the hippocampus formation, a Zn-containing neuron-rich region. In the adult rats, the highest concentration of 65Zn was found in the CA3 and dentate gyrus of the hippocampus formation. At 48 weeks, 65Zn distribution in the cerebellum was relatively low and at about the same level as in the cerebral cortex. These results suggest that Zn is highly demanded by the cerebellum, which develops rapidly after birth. The increase in Zn concentration with increasing age may reflect the Zn requirement for functioning as an neuromodulator as well as for brain development.