Author(s): Teresa DeGolier, Chelsea Lyle and Andrea Ortmann

Abstract: The effect of aqueous extracts from evening primrose seeds, Oenothera biennis, on mouse uterine tissues and rat cervical tissues in vitro were investigated at various concentrations (10-40 mg) using standard 15 mL organs baths. All extract concentrations used increased the force of uterine contractions; the highest concentrations yielded significant increases (P=0.01972). These contractile forces were slightly greater than those evoked from acetylcholine (10^-5 M). Cervical tissues that were pre-contracted with a high potassium solution did not demonstrate any relaxation following 15 min incubations with the evening primrose seed extracts. The badrenergic receptor agonist isoproteronol did relax the cervical tissues by 97% (P=0.05). These results may indicate that some of the evening primrose constituents responsible for (1) uterine contractions are water-soluble and are present in the aqueous extract; and (2) cervical relaxation are primarily lipid-soluble and are present to a greater degree in the oil fraction.