The Effect of Tryptophan on Serotonin-Like Neurons in Duck Cerebellum

Healthy Cherry Valley ducks were used in the present study. Different doses of tryptophan were injected intraperitoneally to them after being fasted 4 h (8:00 a.m.–12:00 a.m.). One hour later, they were deeply anaesthetized and perfused. The cerebellum was removed to make serial paraffin longitudinal sections. The streptavidin-biotin-peroxidase complex (SABC) method was used to study the distribution of serotonin-like neurons in the cerebellum. All films were analysed by using a computer-assisted image analysis system. Serotonin-like neurons are only localized in cerebellar Purkinje cell layer. The optical density averages of serotonin-like neurons in 200 and 100 mg kg−1 group are significantly higher than that of 0 mg kg−1 group (P<0.01). These results show that serotonin-like neurons are distributed in Purkinje cell layer and that excessive tryptophan can affect the content of serotonin in cerebellum.