The Role of Tissue-type Plasminogen Activator in Rat Corpus Luteum

It is here reported for the first time that luteal cells are capable of secreting plasminogen activators (PA),(both tissue-type,tPA,and urokinase-type,uPA),and plasminogen activator inhibitor type-1 (PAl-1).Using organ culture model,we have demonstrated that tPA,but not uPA,showed marked change during luteolytic period in rat corpus luteum.A great amount oftPA was secreted in corpus luteum on D 14 and D 17 while very low level of tPA activity was detected before D 12. Correspondingly,the progesterone production in the corpus luteum increased gradually in a time- dependent manner from D 1 to D 12 but dropped abruptly to a very low level on D 14.Addition of exogenous tPA to the CL culture caused considerable decrease in progesterone secretion while inclusion of purified monoclone tPA antibodies in the culture augmented progesterone production of CL.It is therefore suggested that tPA may play an important role in luteolytic process.