The present work investigated the effect of
MORINDA LUCIDA
(
M. lucida) extract on isolated uterine smooth muscle of pregnant and non-pregnant mice. Pregnant and non-pregnant mice were pretreated with oral stilboesterol (0.1mg/kg body weight) and killed by cervical dislocation. Thin strips of the uterus were cut and mounted in a 20-ml organ bath containing De Jalon solution bubbled with 95%O2-5% CO
2 gas mixture. The strips were connected to a force transducer coupled to a Grass 7D Polygraph for the recording of isometric tension. Effects of graded concentrations of oxytocin (OXY; 10
-5–10
-2 mol/L), acetylcholine (ACh; 10
-9-10
-5 mol/L) and
M. lucida extract (0.015–1.5mg/ml) were recorded. Fresh uterine strips were then incubated with
M. lucida extract for 5mins and cumulative response to OXY was repeated. Another set of fresh strips was incubated in L-NAME for 15mins and the cumulative responses to M.lucida extract were repeated. OXY resulted in increased contractile responses in both pregnant and non-pregnant uterine muscles.
M. lucida resulted in relaxation of the uterine smooth muscle in both pregnant and non-pregnant mice at all doses. However, at 1.500mg/ml,
M. lucida completely blocked spontaneous uterine contractions. Following incubation with L-NAME,
M. lucida extract led to a slightly greater relaxation of the uterine strips. In conclusion,
M. lucida reduced contractility of uterine smooth muscle in both pregnant and non-pregnant mice as well as blocking contractile responses to OXY and Ach in uterine smooth muscle of pregnant and non-pregnant mice. There was no significant alteration of
M. lucida activity by L-NAME suggesting that the action of the compound on uterine muscle is not associated with impaired nitric oxide synthase.
