The binding of [3H]SCH 23390 has been studied in various brain regions of male mice with the experience of repeated victory (winners) or defeat (losers) gained over 10 (T10) and 20 (T20) days of daily agonistic confrontations. In the frontal cortex, B(max) of [3H]SCH 23390 binding sites was found to be increased in T10 losers and decreased in T20 losers when compared to the control mice. In the striatum, T10 and T20 winners had reduced values of [3H]SCH 23390 binding sites than the ones in the

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... ontrol mice. The K(d) was increased in the frontal cortex of T10 losers and T10 winners as well as in the amygdala of T20 losers. Reduced K(d) values were found in the striatum of all experimental groups as well as in the amygdala of T20 winners. Thus, both specific changes relating to social behavior patterns and non-specific ones in [3H]SCH 23390 binding were found in the brain regions of mice after 10 and 20 days of intermale confrontations.