Ex vivo Inhibitory Activity of the Ethanol Root Extract of Senna occidentalis (Labaceae) on Isolated Rat Uterus

Abstract

The ex vivo activity of the ethanol root extract of Senna occidentalis (Labaceae) on isolated rat uterus was examined in order to determine its potential in the therapy of uterine related pathologies. The ethanol root extract of S. occidentalis was investigated on the isolated uterus of rats primed with diethyl stilboestrol (0.1 mg/kg) 24 h prior to the experiment. The extract (2.5 and 7.5 mg/mL) effect on ACh (0.1 – 1.0 μg/mL)– induced contractility, in the presence of atropine (0.12 μg/mL), propranolol (8 μg/mL), CaCl2 (in Ca²⁺-free medium) and in the presence of 100 mM KCl was examined. The extract significantly inhibited ACh-induced uterine contractions (P< 0.05) and CaCl_2- induced uterine contractions (in Ca²⁺-free medium) (P<0.05) in a non-competitive but concentration-dependent manner. A rightward shift of the concentration-response curve was observed in all cases. However, a bell- shaped concentration-response curve was observed for CaCl₂. The inhibitory effect of the extract on ACh-induced uterine contractions was unaffected by propranolol. The extract (0.1 - 0.4 mg/mL) also inhibited KCl- induced uterine contractions. The root extract of S. Occidentalis was shown to inhibit agonist-induced uterine contractions probably through interaction with voltage-operated calcium channels.

Keywords: Acetylcholine; Calcium; Propranolol; Ex vivo uterine activity; Senna occidentalis; Uterus