LYSLY OXIDASE ACTIVITY IN THE MOUSE UTERINE CERVIX IS PHYSIOLOGICALLY REGULATED BY ESTROGEN

Lysyl oxidase activity in the mouse cervix was examined during the estrous cycle, pregnancy, and the postpartum period. It was highest in estrus and lowest in diestrus. On day 1 of pregnancy, the activity was comparable to that seen in estrus. It then declined continuously until day 17 of pregnancy, when it was approximately equal to that seen during diestrus. The activity showed a slight increase toward term, then a precipitous increase occurred on the 1st postpartum day. The activity fell by the 7th postpartum day to a value comparable to that seen in diestrus. Enzyme activity fell to 1/4 of its former value 3 days after ovariectomy. The injection of 1 .mu.g 17.beta.-estradiol or more in 0.9% NaCl 10 days after ovariectomy raised the activity in 18 h to the level seen in estrus. One milligram of progesterone had no effect on the enzyme activity, but a combination of 1 .mu.g 17.beta.-estradiol and 1 mg progesterone raised the activity to that seen with 1 .mu.g 17.beta.-estradiol alone. Apparently lysyl oxidase activity in the mouse cervix is under the control of estrogen.