Gravid Uterine Responses in Wistar Rats administered Pterocarpus santalinoides at Late Pregnancy

There are increasingly significant safety concerns regarding the use of medicinal plants with regard to maternal and fetal health. This is particularly due to the established capacity of some bioactive compounds like phytoestrogens, saponins, and others to influence reproductive hormone levels, enhance contraction of the uterus, and jeopardize the integrity of the myometrium. The effect of ethanol leaf extract of Pterocarpus santalinoides (ELEPS) on the gravid uterus of primigravid Wistar rats during late pregnancy, gestational day 15 – 21, was investigated in this study. Pregnant rats were divided into 5 groups: A, B, C, D, and E, and administered 10ml/kg distilled water, 50 µg/kg misoprostol, 400 mg/kg ELEPS, 600 mg/kg ELEPS, and 800 mg/kg ELEPS, respectively. Results showed dose-dependent adverse effects, including significant weight reduction and complete fetal loss across ELEPS-treated groups C, D, and E. Fetuses exhibited intrauterine growth restriction at lower doses, while the highest dose induced early abortion with uterine involution and hemorrhage. Histological analysis revealed increased endometrial folding, inflammatory cell infiltration, and hyperemia. Immunohistochemistry demonstrated elevated expression of uterine oxytocin receptors (OTR) and cyclooxygenase-2 (COX-2), indicating enhanced contractile and inflammatory pathways. These findings suggest that Pterocarpus santalinoides possesses potent uterotonic and fetotoxic properties, which may be mediated through hormonal disruption, estrogen potentiation, and prostaglandin synthesis, and poses significant risks in pregnancy. The findings from this research suggest that intake of Pterocarpus santalinoides during late gestation is unsafe.

Key Words: Pterocarpus santalinoides, late pregnancy, oxytocin receptors, Wistar rats