Effect of banana peel extract on serotonin immunoreactivity and stool consistency in colon of healthy male Wistar rat

Banana peel is a potential natural source of serotonin precursor, which contains 5-hydroxytryptophan (5-HTP), tryptophan, and some other nutrients needed in serotonin metabolism. Serotonin is a neurotransmitter, which has a role in gastrointestinal motility and may affect stool consistency. The effect of banana peel extract on serotonin immunoreactivity and stool consistency is yet unclear. Here we aimed to investigate the effect of banana peel extract on serotonin immunoreactivity and stool consistency in the male. Twenty-five male Wistar rats (8-10 weeks old), were divided into 5 groups: Control Group (C), a control positive 5-HTP group given 5-HTP 1.50 mg/Kg, Banana Peel Extract Group dose 4 mg/KgBW (T1), Banana Peel Extract Group dose 8 mg/Kg (T2) and Banana Peel Extract Group dose 16 mg/Kg (T3). Stool consistency score was measured to examine stool consistency. Immunohistochemistry staining was measured to examine serotonin immunoreactivity. Oral administration of banana peel extract in T3 group (307.3 ± 69.2) group resulted in the enhancement of serotonin immunoreactivity (p<0.05) compared to the control group (199.9 ± 20.7). Stool consistency score of T1, T2, and T3 groups showed no difference compared to control and positive control groups. These results suggest that the administration of banana peel extract 16 mg/Kg increase serotonin immunoreactivity in male Wistar rat, but it is not related to stool consistenc