BRAIN SEROTONINERGIC SYSTEM AND ANXIETY I N C57BL AND CBA MICE STRAINS

Serotonin metabolism and 5-HT2A and 5-HT1A specific binding were studi ed in high-aggressive C57BL and low-aggressive CBA mice. In three main tests for anxiety (elevated plus-maze, <<dark-light test>>, and socia l contacts) C57BL mice revealed higher anxiety than CBA. Activity of t ryptophan hydroxylase, the key enzyme in serotonin biosynthesis was si gnificantly lower in the midbrain and neostriatum of C57BL than CBA mi ce. The specific binding of [H-3] -ketanserin in C57BL was higher in t he frontal cortex and lower in the neostriatum than in the same struct ures of CBA mice being indicative of the differences in 5-HT2A recepto r density. There were no significant differences in 5-HT1A receptor de nsity (as indicated by specific [H-3] -8-OH-DPAT binding) between the strains, It was suggested that decreased serotonin metabolism and char acteristic distribution of 5-HT2A receptors can underlie the expressio n of genetic predisposition to anxiety and aggression.