Luteolytic effects of DL111-IT in pregnant rats

The present studies were conducted to evaluate the effects of DL111-IT [3-( 2-ethyl phenyl)-5-(3-methoxy phenyl)-1H-1, 2, 4 triazol] on ovaries of preg nant rats. Pregnant rats were i.m. treated with DL111-IT 2.5 mg kg(-1) day( -1) or camellia oleum (vehicle control) 0.2 ml/day from day 6 of pregnancy for 1, 3 or 5 days. Blood and ovaries were collected 24 h after the last in jection. Ovarian fresh weight and protein contents, activities of the 3 bet a-hydroxysteroid dehydrogenase (SP-HSD) and 20 alpha-hydroxysteroid dehydro genase (20 alpha-HSD) in ovaries, and cell apoptosis of corpus luteum (incl uding hematoxylin-eosine stain, in situ 3'-end labeling and nucleosomal ban ding) were estimated. Compared with that in the control group, ovarian fres h weight declined 11% and 22% after DL111-IT-3 days and -5 days; protein co ntent dropped 29% after 5-day administration. DL111-IT for 3 days provoked a marked decrease of serum progesterone, by 31% of the control; the activit y of 3 beta-HSD decreased 34.4% after i.m. DL111-IT for 5 days, while that of 20 alpha-HSD increased dramatically after only one injection of DL111-IT (P < 0.01). Histological analysis and in situ 3'-end DNA labeling indicate d that DL111-IT induced the pyknosis of cells and the formations of apoptot ic bodies and intense oligonucleosomes in luteal cells of pregnant rats. Th e cell apoptosis induced by DL111-IT was further confirmed by evaluation of nucleosomal DNA fragmentation by agarose gel electrophoresis in cultured l uteal cells exposed to DL111-IT for 24 h. In conclusion, all results, inclu ding shrunken luteal cells, decreased concentration of protein content and serum progesterone, changed activities of 3 beta-HSD and 20 alpha-HSD and f ormation of DNA fragments in luteal cells, showed the luteolytic effect of DL111-IT in pregnant rats. (C) 1999 Elsevier Science B.V. All rights reserv ed.