Abstract:

BACKGROUND: Studies have shown that castor bean extract has certain anti-fertility effect; however, there are few reports in China about anti-fertility aspect of castor bean.
OBJECTIVE: To explore the effects of castor oil diet extract on uterine contraction of rats and the content of prostaglandin E2 in amniotic tissue.
METHODS: Sixty Wistar unfertilized adult female rats were selected and randomly divided into normal saline, oxytocin and castor oil diet extract group (n=20 rats/group). Before and after drug administration, contraction intensity, frequency and motility of isolated uterus of rats in each group were observed and recorded. Ninety Wistar adult female rats of gestation for 18 days were selected and randomly divided into normal saline, oxytocin and castor oil diet extract groups (n=30 rats/group). Prostaglandin E2 level in amniotic tissues of rats was measured by radioimmunoassay method. The amniotic tissue of rats in normal saline group was obtained. The amniotic cells were cultured in vitro by adding different concentrations of ricinoleic acid in the culture medium for 18 hours. Prostaglandin E2 level in amniotic cells was measured by radioimmunoassay method.
RESULTS AND CONCLUSION: Compared with before drug administration and normal saline group, contraction intensity, frequency and motility of isolated uterus of rats in castor oil diet extract group were significantly improved after administration. There were no significant differences in contraction intensity and frequency (t=2.321, P > 0.05) after drug administration between oxytoxin and castor oil diet extract groups, however, after drug administration, motility in the castor oil diet extract group was significantly lower (t=2.765, P < 0.05) than in the oxytoxin group. Compared with normal saline group, prostaglandin E2 level in amniotic tissues of pregnant rats in castor oil diet extract group was significantly higher (t=14.91, P < 0.01); however, prostaglandin E2 level in 
amniotic tissue of pregnant rats in the castor oil diet extract group was significantly lower than in the oxytocin group (t=2.769, P < 0.05). Prostaglandin E2 levels in amniotic cells of rats were positively correlated with ricinoleic acid concentration and culture time. These results suggested that castor oil diet extract can enhance contractions and increase prostaglandin E2 levels in amniotic tissue. Ricinoleic acid may be the active ingredient of castor oil diet to induce aboration.