Age-dependent changes of brain GABA levels, turnover rates and shock-induced aggressive behavior in inbred strains of mice.

Shock-induced aggressive behavior (SIAB) is absent or very weak in C57BL/6 (C57) mice at the age of 12 weeks while it reaches high levels at the age of 20 weeks. This age-dependent increase of aggressive responses is absent in DBA/2 (DBA) mice. Aggressive C57 mice (20 week old) are characterized by lower GABA levels in amygdala, striatum and substantia nigra than both non-aggressive C57 (12 week old) and DBA mice (12-20 week old). Concerning turnover rate, C57 mice at the age of 20 weeks show lower turnover rate values in cerebellum and raphe and higher values in septum in comparison with 12 week old mice of the same strain. These results are discussed in terms of the role of GABA function in brain areas which are involved in the control of emotionality and aggressive behavior.