Fighting among C57BL/6J mice and its implications for [3H]8-hydroxy-N, N-dipropyl-2-aminotetralin binding in various brain regions.

The binding of [3H]8-hydroxy-N, N-dipropyl-2-aminotetralin ([3H] 8-OH-DPAT) 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. The Bmax of [3H]8-OH-DPAT binding sites was found to be decreased in the hippocampus of the T20 winners when compared to the T10 winners or the control mice, and increased in the amygdala of the T20 losers. The Kd was increased in the amygdala of the T20 losers when compared to the animals of any other experimental group. No change in [3H]8-OH-DPAT binding was observed in the midbrain or the hypothalamus of the winners or losers. It was concluded that the 20-day agonistic confrontations, arranged in order to categorize the mice as winners or losers, had opposing effects on [3H]8-OH-DPAT binding.