Morphological studies on the mechanism of anti-implantative and early-pregnancy-terminative effect by norethisterone oxime in rats
In this study it was found that norethisterone oxime (NorO) could produce changes in some organelles of the ovarian corpora lutea in early pregnant rats including decrease in smooth endoplasmic reticulum, accumulation of lipid droplets, swelling of Golgi bodies and increase in secondary lysosomes. NorO also depressed the activity of 3β-hydroxysteroid dehydrogenase in the ovary, resulting in the obstruction of biological synthesis of steroid hormone in the ovary. It was found that the activity of acid phosphatase of the corpora lutea increased, which showed an increase in the membrane permeability of lysosomes and damage to the cells. Morphological changes unfavourable to implantation occurred in the endometrium of the early pregnant rats, such as, decrease in the transformation of stroma cells into decidual cells, degeneration and necrosis of the decidual cells. On the 4th day of pregnancy estrogenic effect could be detected in the endometrium of the rats. Further study should be made to determine whether this is due to the depression of progesterone level by NorO and thereafter less depression of the action of estrogen or due to the estrogenic activity of the drug itself.