Prostaglandin E and F2 alpha levels in plasma and amniotic fluid during mid-trimester abortion induced by trichosanthin.

ABSTRACT

This paper gives a brief account concerning the estimation of PGE and PGF2 alpha concentrations in both plasma and amniotic fluid by radioimmunoassay in mid-trimester abortion induced by Trichosanthin. The significant change in amniotic fluids as compared with that in plasma is brought out for discussion as an aid to the study of mechanism of abortion by Trichosanthin.

ABSTRACT

PIP Trichosanthin, an abortifacient plant protein isolated from Radix Trichosanthes, has a success rate of approximately 98%. This paper examines changes in prostaglandin (PG) E and F2alpha levels in both plasma and amniotic fluid by radioimmunoassay in midtrimester abortion induced by Trichosanthin. Trichosanthin was given by transabdominal amniotic injection (average dosage, 8-11 mg) in 8 women (7 primigravidae and 1 secundigravida) of 17-24 weeks gestation. Venous blood and amniotic fluid samples were collected both before and after drug administration. PGE and F2alpha in plasma and amniotic fluid were measured by radioimmunoassay based upon a method described by the Pekin Institute of Zoology. Injection-abortion time ranged from 72-168 hours with a mean of 100 hours. No significant change was observed between concentrations of PGE and PGF2alpha in the plasma before and after drug administration, probably due to the fact that the 2 PGs were released in pulsatile fashion instead of continuous, and because PGs have short half-life in the circulating blood. In contrast, both PGE and PGF2alpha levels in the amniotic fluid were markedly increased after Trichosanthin administration, the increments amounting to 12.8 and 23.8 times the preinjection value respectively (p0.001). In midtrimester abortion, Trichosanthin exerts a selective action on the syncytiotrophoblasts as demonstrated by their degenerative and necrotic changes and simultaneous deciduitis. These injuries are followed by impairment of the endocrine functions of the placenta, a disintegration of lysosomes inside the decidual cells, and a decreased stability of the lysosomal membrane, an increase of synthesis of PGE and PGF2alpha both in the fetal membrane and decidua, and finally, complete abortion.