| Background and Aim:The peach tree, Prunus persica (L.) Batsch is widely cultivated in China, and its flowers have been used for centuries in traditional Chinese medicine to treat gut motility disorders. Despite a long history of the use of Prunus persica (L.) Batsch flowers in traditional Chinese medicine, few studies have explored the pharmacological effect of these preparations on gastrointestinal motility or the underlying mechanism of action. The present study aims to investigate the mechanisms by which Prunus persica (L.) Batsch flowers regulate gastrointestinal motility by exploring the effects on gastric emptying and small intestinal transit and also by examining the effects on spontaneous smooth muscle contractions in isolated rat colonic tissue.Methods:The systemic solvents extractions of phytochemistry were used for extracting Prunus persica (L.) Batsch flowers and the resulting extracts were administered orally to rats fed with phenol red to investigate gastric emptying rate and intestinal transit rate. The effects of an ethyl acetate extract (EAE) on motilin or gastrin concentration in rat serum at different time were evaluated using the enzyme-linked immunosorbent assay. The effect of an ethyl acetate extract (EAE) on smooth muscle contractions was evaluated using isolated colonic tissue. To investigate the EAE-induced effects on spontaneous contractions, various blockers or antagonists were added before treatment with EAE. Toluidine blue staining and immunofluorescence were used to observe the changes in mast cells in colonic tissue. A RIA kit was used to measure EAE-induced histamine release.Results:EAE showed prokinetic activity in rats at a dose of 0.9 g/kg compared with the control group, with a statistically significant difference (p<0.01). There is no statistically significant difference in the EAE group compared with the mosapride group (p>0.05). And there were no obvious prokinetic activity of n-butanol extract (NBE), chloroform extract (CE) and petroleum ether extract (PEE). Compared to control group, EAE group could increase the concentration of gastrin and motilin at 30 and 60 min, but with a statistically significant difference at 60 min (p<0.05). EAE concentration-dependently increased the frequency and amplitude of colon muscle contractions in the concentration range 10-8-10-3g/mL but exerted an inhibitory effect at higher concentrations. The contractile effect (amplitude 150.4±13.12%) in the presence of EAE at a concentration of 10 g/mL was comparable to the basal level. EAE induced a definite contraction of the longitudinal muscle in the isolated rat colon strip at a dose of 10-6 g/mL (p<0.01). Pretreatment with with atropine, tetrodotoxin, norepinephrine, EGTA and indomethacin did not inhibit the EAE-induced contraction. But pretreatment with cimetidine, pyrilamine or ketotifen could inhibit the EAE-induced contraction. The EAE-treated group was found to have many more mast cells in the colon compared with the control group (p<0.05). Mast cells in the EAE-treated group also showed an increase in cell volume together with signs of degranulation compared with the control group. Immunofluorescence technique, which can reveal circumscript staining for mast cell tryptase, could also showed increased numbers of mast cells in the EAE group compared to the control group. The basal concentration of histamine in colon tissue was 0.68±0.05 ng/mg. The histamine concentration in colon tissue treated with EAE decreased to 0.46±0.05 ng/mg (p< 0.01). Following pretreatment of the colon tissue with ketotifen (100μM) for 10 min before adding the EAE, the histamine concentration in the tissue was 0.66±0.07 ng/mg (p>0.05). Simultaneously, the basal concentration of histamine in the supernatant of rat colon tissue was 0.15±0.02 ng/mL. Following treatment of the colon tissue with EAE, the histamine concentration increased to 0.30±0.03 ng/mL (p<0.01). If the colon tissues were pretreated with ketotifen (100 μM) for 10 min before adding the EAE, the histamine concentration was 0.18±0.03 ng/mL (p> 0.05).Conclusion:1. The systemic solvents extractions of phytochemistry were used for extracting Prunus persica (L.) Batsch flowers, and four separate extracts were thus obtained:a petroleum ether extract (PEE), a chloroform extract (CE), an ethyl acetate extract (EAE) and an n-butanol extract (NBE). EAE was the most effective fraction from the Prunus persica (L.) Batsch flowers extracts.2. EAE showed prokinetic activity at low-dose but exerted an inhibitory effect at higher dose. Prokinetic activity has been showed a significantly dose dependence.3. EAE could promote the secretion of gastrin and motilin, and mast cells in the EAE-treated group also showed an increase in cell numbers together with signs of degranulation compared with the control group.4. The mechanism involved in the stimulatory action of EAE may be related to its adjusting the release of gastrin and motilin, and mediated via mast cell degranulation, which increases histamine levels in the intestine. |
