Physiological Response of uterine muscle to aqueous root extract of Steganoteania Araliacea Hochst (Herbal''Pitocin'') in Rats

Abstract

Background: The bark root of Steganotaenia araliacea Hochst (Umbelliferae) nicknamed “herbal pitocin” is used in the traditional circles in Zambia to induce and/or enhance labour. This work was aimed at investigating the contractile stimulatory effects of the aqueous extracts of Steganotaenia araliacea (SAEª) on isolated smooth muscle preparations of the rat uterus. Objectives: To determine the physiological effect of SAEª on isolated pregnant and non-pregnant uterine muscle. Methods: A gravid/non-gravid rat was sacrificed by cervical dislocation (decapitation) method and the abdomen opened to expose the internal organs. The two uterine horns were identified, dissected out and transferred to a dish containing De Jalon’s physiological solution. Acetylcholine (Ach) and Oxytocin (OT) were used as reference agonist with their corresponding antagonists; atropine (AT), and indomethacin and salbutamol (SBM) respectively. The effect of these reference agonists with their corresponding antagonist and that of aqueous extract of SAE on non-pregnant rat uterus pre-treated with 1 mg/kg stilboesterol for 24 h and on the pregnant rat uterus were investigated. Results: In vitro studies of SAEª on uterine tissue showed contractile (uterotonic) activity on both isolated gravid and estrogenized non-gravid rat uterus at the concentration shown in this study. SAE ª significantly increased the amplitude(from baseline value of 0.1471mN to 0.3003mN) and frequency of spontaneous uterine contractions. However, SBM significantly inhibited (p < 0.05) the frequency and amplitude of spontaneous uterine contractions on the isolated pregnant and non – pregnant rat uterus preparations but atropine and indomethacin could not modify the contractions produced by SAEª, hence indicating a non-muscarinic and non-prostaglandin biosynthesis dependant respectively. Conclusion: The inhibition of contractile effect of the crude aqueous extract of SAEª shown by Salbutamol (p < 0.05) suggests the probable stimulation of the Oxytocinergic receptors of the uterus by the extract. These physiological finding justify the traditional use of the plant for its uterotonic properties.