Tariro Mawoza
University of Zimbabwe Medical School, Zimbabwe
Title: Spasmogenic effects of Sclerocarya birrea stem bark aqueous extract on rat isolated uterine horns
Biography
Biography: Tariro Mawoza
Abstract
Sclerocarya birrea is used as a traditional remedy for allegedly treating dysmenorrhoea and a host of other ailments. This study investigated the pharmacological effects of S. birrea extract (SBE) uterine horns from Wistar rats. One kilogramme of S. birrea fresh stem bark was air-dried at room temperature (26±1°C) for two weeks, milled and macerated in 2.5 litres of distilled water for 48 hours and filtered. A rotary evaporator was used to concentrate the aqueous extract and freeze-drying gave 6.13% yield of the extract. Rat isolated uterine horns were mounted in 25-ml Iworx tissue organ-baths containing De Jalon’s physiological solution, and exposed to SBE (25, 50, 100, 200, 300, 400mg/ml/kg). The effects of SBE and atropine, oxytocin, verapamil indomethacin, acetylcholine, serotonin, cimetidine and histamine on the isolated uterine horns were recorded using LabScribe2 software. S. birrea produced significant (p<0.05) concentration-dependent contractions of the uterine muscles reaching a maximum at the 300mg/ml dose. SBE mimicked and potentiated the contractile effects of oxytocin (0.5-5μU/ml) and acetylcholine (0.1-3μg/ml). Pre-incubation of tissues with atropine (1-3μg/ml), non-significantly (p>0.05) inhibited SBE-induced contractions on uterine muscles. Verapamil (2μg/ml), indomethacin and -p-tosyl-l-phenylalanine-chloromethyl-ketone (TPCK) inhibited the contractile effects of SBE suggesting possible calcium mediated mechanism of action for SBE and possible COX-enzyme inhibition. Pre-incubating tissues with histamine (10-8-10-5M) resulted in relaxation of the uterus, while cimetidine potentiated the contractile effects of SBE. Serotonin potentiated the contractile effects of SBE. These results indicate that SBE causes contraction on uterine smooth muscles possibly through its effects on oxytocin, acetylcholine and serotonin receptors. As a result SBE should not be used by patients suffering from dysmenorrhoea as it can worsen it or pregnant patients as it can result in miscarriage/abortion.