Activity and subcellular distribution of mouse uterine alkaline phosphatase during pregnancy and pseudopregnancy

Abstract

The biochemical assay of alkaline phosphatase in the uterus of mice revealed a 13-fold increase in the activity of the enzyme during the peri-implantation period with a relatively short-lived maximum being reached on Day 7 of pregnancy. A similar increase in the activity of the enzyme occurred between Days 5 and 7 of pseudopregnancy in uterine horns of mice receiving a deciduoma-inducing stimulus on Day 4. The presence of factors in uterine homogenates which could possibly modify the activity of the enzyme could not be detected. Low and unaltered levels of alkaline phosphatase activity were found in the blood serum of mice between Days 1 and 10 of pregnancy, suggesting that no appreciable entry of the uterine enzyme into the circulation occurs in this species. Alkaline phosphatase activity in the uterine homogenates was associated with particulate fractions sedimented during centrifucation at at 500, 10,000 and 105,000 g, and only about 29% of the activity was associated with the cytosol fraction. The subcellular distribution of the enzyme activity was the same in decidualized and non-decidualized horns. The association of the enzyme with the particulate material in uterine cells was considered to involve lipoprotein membranes because treatment of homogenates with 0.2% (v/v) Triton X-100 solubilized the enzyme without affecting its catalytic activity.

Foetotoxicity of Cadmium in Quackenbush Strain Mice and the Effects of the Metal on Uterine Alkaline Phosphatase During Pseudopregnancy

“…These are characteristic features of the decidual reaction and have been described previously (Finn and Hinchliffe 1964;Murdoch et at. 1978).…”

“…Female QS mice, aged 7-9 weeks, were used in all experiments and were housed as previously described (Murdoch et al 1978). Pregnancy and pseudopregnancy were brought about by pairing the females with intact or vasectomized males, respectively.…”

“…Deciduomata were induced in the left uterine horns of these mice on day 4 by the intraluminal injection of 30 III of peanut oil as previously described (Murdoch et al 1978). Six mice were used in each treatment group and the animals were killed by cervical dis1ocation between 0900 and 1000 h on day 7 of pseudopregnancy.…”

“…It is possible, therefore, that in vivo inhibition of alkaline phosphatase in uterine decidual cells by cadmium could lead to functional alterations in the decidua which may be detrimental to the developing embryo. This possibility gains credence from the work of Dencker (1975) who showed that, during early gestation in mice, intravenously injected cadmium accumulated not only in the maternal ovary and primitive gut of the developing embryo, but also in the uterine decidua and placenta where alkaline phosphatase activity is normally high (Murdoch et al 1978).…”

“…In this context, alkaline phosphatase (orthophosphoric monoester phosphohydrolase, EC 3.1.3.1) from the pregnant mouse uterus is a zinc-containing metalloenzyme and is also inhibited in vitro by cadmium (Murdoch et al 1980). This enzyme is associated with the induction of the decidual cell reaction during early pregnancy (Finn and Hinchliffe 1964;Murdoch et al 1978) and may play an important role in facilitating maternal-embryonic relationships during the peri-implantation period. It is possible, therefore, that in vivo inhibition of alkaline phosphatase in uterine decidual cells by cadmium could lead to functional alterations in the decidua which may be detrimental to the developing embryo.…”