Effect of tokishakuyakusan on corpus luteum endothelin

The presence of endothelin-1 (ET) and effect of Tokishakuyakusan (TS) on ET in rat corpora lutea (CL) was investigated in superovulated ovaries, induced with pregnant mare's serum gonadotropin and human chorionic gonadotropin. A high concentration of ET was found in the CL. The level of ET was significantly lower in the CL from TS-treated rats than that in TS-untreated rats (402.68 versus 575.60 pg/g wet weight, p less than 0.05). In contrast, the ET levels in plasma were by far lower than those in CL. These data indicate an inhibitory effect of TS on ET, an intraovarian peptide, production or accumulation in the CL.