The expression pattern of GGT catalytic activity along the rat epididymal duct in this study confirms previous observations that proximal regions of the rat epididymis have higher GGT catalytic activity than the distal regions . The values of GGT catalytic activity in the caput and cauda regions are also in agreement with previous reports . The decrease of GGT catalytic activity in the initial segment following 3 days of EDL (Fig. 1) is probably due to decreased GGT protein level (Fig. 2). buy ortho tri-cyclen online
Previous studies have shown that GGT mRNA-IV is highly expressed in the initial segment and that the expression of GGT mRNA-IV decreases after loss of testicular factors . It is suggested that the decreased GGT protein level and GGT catalytic activity are at least partially due to the decreased expression of GGT mRNA-IV. However, the expression of GGT mRNA-IV decreases about 50% and 80% of the sham control value by 12 h and 24 h of EDL . If GGT mRNA-IV is responsible for maintaining high GGT catalytic activity in the initial segment, then the level of GGT catalytic activity in the initial segment by 3 days and 14 days after EDL would be reduced to about 50% and 10% of the sham value, respectively, considering the 3- to 5-day half-life of GGT protein.