Extracellular (36Cl) space, electrolyte, protein, and DNA content in brain of DBA and C57 mice: effects of age.

Abstract

DBA/2J (DBA) mice are susceptible to audiogenic seizures (AGSs) in an age-dependent manner, susceptibility being maximal at 21 days and absent at 110 days of age. Previous studies have demonstrated that there is a decrease in anion transport and an increase in carbonic anhydrase (CA) activity in brain from DBA mice as compared with C57BL/6J (C57, non-AGS) mice at 21 days. Since these results suggest that there are alterations in cellular and electrolyte composition of brain from DBA mice, the present work was directed toward determining electrolyte content, extracellular space, and DNA content of brain from DBA and C57 mice at 21 and 110 days of age. There was a decrease in intracellular chloride and sodium content, and an increase in intracellular potassium content in cerebral cortex, cerebellum, and brainstem from DBA mice at both 21 and 110 days. Also, extracellular space was larger in these three brain tissues from DBA mice at both ages. DNA content, not different between the strains at 21 days, was significantly lower in cerebellum from DBA mice at 110 days. These findings give further evidence of alterations in the transport of ions in brain from DBA mice. In addition, they demonstrate that there are alterations in the intracellular and extracellular space values, an indication of changes in cellular composition of brain in these mice. Such changes may contribute to AGS susceptibility by disrupting the balance that normally exists in the neuronal microenvironment of the central nervous system.