Free zinc increases at the site of injury after cortical stab wounds in mature but not immature rat brain.

The accumulation of free zinc (Zn2+) appears to play a role in the neuronal degeneration that occurs after brain injury. Given that neonates respond to brain injury with increased plasticity compared to adults, this study compared the effect of age on free Zn2+ and the Zn2+-binding protein metallothionein-3 (MT-3) after injury. Unilateral cortical stab wounds were produced in 3-day-old and adult rats. Four weeks later, brains were removed for in situ visualization of free Zn2+ and measurement of MT-3 mRNA. Free Zn2+ and MT-3 mRNA accumulated after 4 weeks at the site of injury site when injury occurred in adults. However, 4 weeks after neonatal injury there was no increase in free Zn2+ or MT-3 mRNA in or around the site of injury.