[The characteristics of the brain serotonin system and anxiety in the C57BL and CBA mouse strains].

Serotonin metabolism and 5-HT2A and 5-HT1A specific binding were studied in high-aggressive C57BL and low-aggressive CBA mice. In three main tests for anxiety (elevated plus-maze "dark-light test", and social contacts) C57BL mice revealed higher anxiety than CBA, Activity of tryptophan hydroxylase, the key enzyme in serotonin biosynthesis was significantly lower in the midbrain and neostriatum of C57BL than CBA mice. The specific binding of [3H]-ketanserin in C57BL was higher in the frontal cortex and lower in the neostriatum than in the same structures of CBA mice being indicative of the differences in 5-HT2A receptor density. There were no significant differences in 5-HT1A receptor density (as indicated by specific [3H]-8-OH-DPAT binding) between the strains. It was suggested that decreased serotonin metabolism and characteristic distribution of 5-HT2A receptors can underlie the expression of genetic predisposition to anxiety and aggression.