Antispasmodic effect of Physalis alkekengi fruit extract on rat uterus

Background: Studies have shown that Physalis alkekengi reduces implantation and induces antifertility in rat. In Iranian traditional medicine it is believed that this plant has abortifacient and antifertility activities. Objective: The goal of this study was to evaluate the effect of Physalis alkekengi ripe fruit hydroalcoholic extract (PFE) on uterine contractility and its possible mechanism(s). Materials and Methods: Extraction of Physalis alkekengi fruit was carried out by maceration method (70% alcohol). Uterus was dissected out from adult non-pregnant rat (Wistar) and contracted by KCl (60mM) or oxytocin (10mU/ml) in an organ bath containing De Jalon solution and the effect of PFE on the uterine contractions was investigated. Furthermore, the role of ?- and B-adrenoceptors, opioid receptors, nitric oxide and cyclic guanosine monophosphate synthesis inhibitors on the extract effects were evaluated. Results: KCl- and oxytocin-induced uterine contractions were inhibited (p < 0.001) by the cumulative concentrations of the extract in a concentration dependent manner. Incubation of uterus with propranolol (1?M) and L-NAME (100?M) attenuated the PFE antispasmodic effect (p < 0.05). But the PFE effect was unaffected by phentolamine (1?M), naloxone (1?M) or methylene blue (10?M). In Ca2+-free with high potassium (60mM) De Jalon solution, cumulative concentrations of CaCl2 (0.1-0.5mM) induced uterine contraction concentration-dependently (p < 0.001). Uterus incubation (5min) with PFE (0.25-1.75mg/ml) attenuated the CaCl2–induced contractions (p < 0.05). Conclusion: It seems that the extract induced antispasmodic effect mainly via calcium influx blockade and partially through blocking B-adrenoceptors and nitric oxide (NO) synthesis. However, neither ?-adrenoceptors nor opioid receptors or cGMP synthesis were involved.