title: Spasmogenic effects of Sclerocarya birrea stem bark aqueous extract on rat isolated uterine horns.
abstract: BACKGROUND
  Sclerocarya birrea (Anacardiaceae), popularly known as "marula", is used as a traditional remedy for allegedly treating dysmenorrhoea and a host of other ailments such as malaria, fever, diarrhoea, dysentery, stomach disorders, headaches and to facilitate childbirth. This study investigated the pharmacological effects of S. birrea extract (SBE) on isolated, spontaneously-contracting uterine horns of healthy, young adult, female Wistar rats.
  
  
  METHODS
  One kilogramme of S. birrea fresh stem bark was identified and authenticated. The bark was air-dried at room temperature (26 ± 1°C) for two weeks. The dried stem bark was milled and macerated in 2.5l of distilled water for 48 h and filtered. A rotary evaporator was used to concentrate the aqueous extract by drying it at 60 ± 1°C. Freeze-drying gave 61.3g/kg (i.e., 6.13% yield) of a dark-brown, powdery, crude extract. Rat isolated uterine horns were mounted in 25-ml Iworx tissue organ-baths containing De Jalon׳s physiological solution, and exposed to graded concentrations of 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 muscles, were recorded using LabScribe2 software.
  
  
  RESULTS
  The aqueous stem bark extract of S. birrea produced significant (p<0.05) concentration-dependent contractions of the uterine horn muscle preparation reaching a maximum at the 300 mg/ml dose. SBE mimicked and potentiated uterine muscle contractile effects of oxytocin (0.5-5 µU/ml) and acetylcholine (0.1-3 µg/ml). Pre-incubation of tissues with atropine (1-3 µg/ml), non-significantly (p>0.05) inhibited SBE-induced contractions on uterine muscles. Verapamil (2 µg/ml), indomethacin and -p-tosyl-l-phenylalanine-chloromethyl-ketone (TPCK) inhibited the contractile effects of SBE (25-400mg/ml/kg), suggesting possible calcium-mediated mechanism of action for SBE and possible COX-enzyme inhibition. Pre-incubating tissues with histamine (10(-8)-10(-5)M) resulted in relaxation of the uterus, while cimetidine potentiated the contractile effects of SBE. Serotonin potentiated the contractile effects of SBE.
  
  
  CONCLUSIONS
  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.
authors: Department of Clinical Pharmacology, University of Zimbabwe College of Health Sciences, P.O. Box A178, Avondale, Harare, Zimbabwe. Electronic address: tmawoza@gmail.com.
authors: Tariro
authors: T
authors: Mawoza
authors: Department of Clinical Pharmacology, University of Zimbabwe College of Health Sciences, P.O. Box A178, Avondale, Harare, Zimbabwe.
authors: Dexter
authors: D
authors: Tagwireyi
authors: Department of Clinical Pharmacology, University of Zimbabwe College of Health Sciences, P.O. Box A178, Avondale, Harare, Zimbabwe.
authors: Charles
authors: C
authors: Nhachi
mesh_terms: D027926:Anacardiaceae; D000818:Animals; D005260:Female; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D024301:Plant Bark; D010936:Plant Extracts / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D014599:Uterus / Q000187:drug effects* / Q000502:physiology
chemical_list: D010936:Plant Extracts
keywords: Aqueous extract; Contraction; Sclerocarya birrea; Uterus