Reduction in aggressive behavior and increase in 5-HT metabolism by the
precursor 5-HTP. (A and B) Aggressive
behavior as measured by the resident–intruder test 30 min after 0.9%
saline solution, 50 mg/kg or 100 mg/kg 5-HTP i.p. injections in WT
and nNOS−/− mice (n = 6 each group).
(C) Locomotor activity in an open field 30 min after
i.p. injections in different animals (saline and 5-HTP 100 mg/kg,
n = 6 in each genotype; and 5-HTP 50 mg/kg,
n = 5 in each genotype). *,
P < 0.05; and †, P < 0.01 in
relation to the saline group in the same genotype; and #,
P < 0.05; and ##, P < 0.01 in
relation to WT same treatment. Data are means ± SEM and were
analyzed by using two-way ANOVA (genotype × treatment) with post
hoc Tukey test. (D) HPLC determinations of 5-HT (S) and
its metabolite 5-HIAA (M) in the cerebral cortex (Cor), hypothalamus
(Hyp), hippocampus (Hipp), amygdala (Amy), midbrain (Mid), and
cerebellum (Cer) of WT and nNOS−/− mice
(n = 5 each genotype) 45 min after 100 mg/kg
5-HTP. Data are percent increase above saline groups in each genotype
(n = 6 each; means ± SEM). The percent of
turnover increase (5-HIAA/5-HT) ranged from 346% to 646% in these
brain areas. All data in D are P <
0.01 in relation to saline controls (two-way ANOVA with post hoc Tukey
test).