[Spasmolytic activity of Piper nigrum fruit aqueous extract on rat nonpregnant uterus]

ABSTRACT

Piper nigrum [Black pepper] from Piperaceae is main constituent of food spice and piperine as its main component increases bile and small intestine secretions, but reduces the gastric emptying and increases intestine transit time in rat and mouse. In traditional medicine, black pepper is used for relief of menorrhalgia in women but this effect has not been evaluated scientifically. The study was performed to investigate the effect of black pepper fruit aqueous extract on rat non-pregnant uterus contractions and the mechanism[s] of its action. Aqueous extract of black pepper was prepared by adding 10 g of black pepper powder to 200 ml of boiling distilled water for 15 min and after filtering, solvent was evaporated. Uterus was dissected from non-pregnant adult rat [Wistar] and in an air bubbled De Jalon solution; contractions were recorded isometrically under 1 g tension. Cumulative concentrations of black pepper aqueous extract [0.125, 0.25, 0.5, 1 and 2 mg/ml] reduced the uterus contractions induced by KCl [60mM] and oxytocin [10mU/ml] dose dependently [p<0.0001]. The spasmolytic effect of extract on the KCl-induced contractions was unaffected by L-NAME [100 micro M] but rather increased by phentolamine [1 micro M] and naloxone [1 micro M]. However, propranolol [1 micro M] reduced the extract spasmolytic effect significantly [p<0.01-p<0.0001]. In calcium free De Jalon solution with high potassium [60mM], extract [0.0312, 0.625, 0.125 and 0.25 mg/ml] reduced the contractions induced by cumulative concentrations of calcium chloride [0.1-0.5mM] dose dependently [p<0.05- p<0.0001]. Our results suggest that the spasmolytic effect of black pepper aqueous extract on rat uterus was mediated via voltage dependent calcium channels and also beta-adrenoceptors could be involved in this action. However, the alpha-adrenoceptors, opioid receptors and nitric oxide generation were not involved. Our results may support the usage of black pepper for relief of menorrhalgia in women