Physiological response of uterine muscle to Steganoteania araliacea in rat models

Abstract

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.