GAMMA-GLUTAMYL-TRANSFERASE (GGT) ACTIVITY AND BIOCHEMICAL-CHARACTERIZATION OF RAT VISCERAL YOLK-SAC DURING GESTATION WITH OR WITHOUT TRYPANBLUE EXPOSURE

Yolk-sacs from untreated Sprague-Dawley rat conceptuses were removed o n gestational days (GD) 9 to 18 and examined for gamma glutamyl transf erase (GGT), alkaline phosphatase (AP), lactate dehydrogenase (LDH), a nd glutamic-oxaloacetic transaminase (GOT) activities. All enzyme acti vities were found to increase through gestation in total activity as w ell as in specific activity. Protein (PRO) and urea nitrogen (UN) were also found to increase through gestation whereas triglyceride (TRI) i ncreased steadily from GD 9 to 13 and then appeared to plateau through GD 19. Additional rats were treated on GD 8 with 75 mg trypan blue (T B)/kg body weight and yolk-sacs taken on GD 9 to 18. Yolk-sac GGT and GOT activities from TB-treated rats were significantly higher than the respective control during early gestation but recovered to or were lo wer than control levels during midgestation. GGT activity in treated r ats was significantly higher than the controls on GD 15 and 16, and bo th GGT and GOT were significantly lower than controls on GD 17 and 18. AP activity in the TB-treated yolk-sacs was significantly lower than that in controls during early and midgestation but was not significant ly different from the control values late in gestation, Triglyceride c oncentration was not affected early in gestation but significantly dec reased on GD 16 and 18. Thus, the yolk-sac enzymes monitored, which ar e associated with nutrition and normal growth, increased in activity t hrough GD 18. The yolk-sac toxicant, trypan blue, significantly affect ed enzymatic activity at various time periods during gestation and res ulted in significant changes in yolk-sac protein and triglyceride cont ent.