EFFECT OF REPEATED EXPERIENCE OF VICTORY AND DEFEAT IN DAILY AGONISTIC CONFRONTATIONS ON BRAIN TRYPTOPHAN-HYDROXYLASE ACTIVITY

The rate-limiting enzyme of serotonin biosynthesis, tryptophan hydroxy lase (TPH), was studied in brain areas of male mice with repeated expe rience of victory (winners) or defeat (losers) gained in 10 daily agon istic confrontations, A reduction of TPH activity in the midbrain and an increase in the hypothalamus was demonstrated for winners compared with controls, In contrast, repeated defeat in social confrontations w as associated with higher TPH activity in the striatum and hypothalamu s in losers compared with controls, Agonistic interactions did not aff ect TPH activity in the amygdala, nucleus accumbens or hippocampus in either winners or losers, The sensory contact technique used in this w ork for generating winners and losers may be productive in the analysi s of TPH gene regulation. (C) 1997 Federation of European Biochemical Societies.