Ananas comosus extract mediates uterotonic effect through serotonergic pathway

Ananas comosus is traditionally used to act as an abortifacient. We have previously shown that A. comosus extract can stimulate the uterine motility in vitro [1]. However, the in vitro technique may not reflect the complexity of cellular interactions occurring in vivo. This study is expected to provide information on uterotonic effect of A. comosus extracts in vivo as well as the underlying molecular mechanisms.

The ethanolic crude extract of A. comosus was prepared and fractionated through a series of liquid-liquid partitions. Total proteins were isolated from uterine strips following the functional studies for western blot analysis. The PhysioTel transmitter (PA-C40) was implanted under aseptic techniques in pregnant SD rats to measure intrauterine pressure (IUP).

Similar to serotonin, fraction 4 initiated the signal transduction through activation of ERK1/2, which resulted in the production of MMP-13. This data indicated the contribution of serotonergic pathway in the uterotonic activity of A. comosus extract. In pregnant animals (E18 and E19), F4 (1.5 g/100 g body weight), ergometrine (1 mg) and vehicle control (5 mL) did not stimulate the uterine contraction following oral administration. The lack of efficacy of the F4 in rat model is possibly due to low level of estradiol and as a consequent low 5-HT receptors at the time of administration. In contrast, IUP increased 20 hour following injection of mifepristone (15 mg) on E18 which caused premature labor in SD rats. In postpartum rats, oral administration of F4 and ergometrine showed significant increase in maximal IUP to 4.3 and 4.9 folds of basal IUP respectively (p < 0.05, student's t test, n = 8) suggesting that the active principle in aqueous fraction can serve as a drug lead in postpartum haemorrhage.

[1] Monji, F, Adaikan, P.G, Lau, L.C, Said, B.B, Gong, Y, Tan, H.M, Choolani, M, J Ethnopharmacol 2016; 193: 21 – 29.