An Investigation into the Role of Neutrophils in Decidualization and Early Pregnancy in the Rat1

Abstract

Possible roles for neutrophils in the response of sensitized rat uteri to a deciduogenic stimulus were investigated. Ovariectomized rats were sensitized for the decidual cell reaction by the administration of estradiol and progesterone. Sesame oil was injected into one uterine horn as a deciduogenic stimulus on the equivalent of Day 5 of pseudopregnancy. Neutrophil numbers in the endometrium, as determined by microscopy after application of the stimulus, were dependent on time and stimulation. Very few neutrophils were found in the endometrium before stimulation. To determine whether neutrophils were involved in the uterine responses to a deciduogenic stimulus, rats were depleted of circulating neutrophils by prior treatment with either methotrexate (MET) or antineutrophil serum (ANS). The increase in endometrial vascular permeability, as quantified with [125I]-BSA 10 h after stimulation, was not significantly affected by MET or ANS treatment, nor was the extent of decidualization, as indicated by the weight of the uteri 5 days after stimulation. Endometrial neutrophil numbers were significantly lower in the MET- and ANS-treated animals compared to their respective controls. In the uterus, activity of myeloperoxidase, an enzyme found mainly in neutrophils, was significantly reduced in MET-treated animals. To investigate the role of neutrophils in blastocyst implantation, we treated rats with ANS early on Day 5 of pregnancy. On Day 6, neither the numbers of implantation sites nor their weights were affected by ANS treatment. ANS treatment on Day 5 of pregnancy did not attenuate the numbers and weights of placentae and fetuses on Days 19 and 20 of pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Progesterone via Its Receptor Antagonizes the Pro-Inflammatory Activity of Estrogen in the Mouse Uterus1

“…Neutrophil numbers in the mouse uterus are high around the time of implantation, a time when P 4 levels are high. Subsequent studies showed that systemic depletion of neutrophils had no discernible effect on implantation, leaving the importance of neutrophil infiltration into the deciduum unclear [32]. In the current study, regulation of neutrophil accumulation in the uterus paralleled that of macrophages, with estrogen having a positive effect on uterine neutrophil numbers and P 4 having a PR-dependent negative effect.…”

“…The reaction of the uterus to implantation has been said to resemble an inflammatory response, with local production of a number of inflammatory mediators and resultant influx of neutrophils [29][30][31][32]. Neutrophil numbers in the mouse uterus are high around the time of implantation, a time when P 4 levels are high.…”

Expression of type VI collagen mRNAs in human endometrium during the menstrual cycle and first trimester of pregnancy

“…We reported that collagen VI protein is present as an extracellular fibrillar array in the stroma of proliferative, early and mid-secretory phase endometrium (Aplin et al, 1988 (Finn, 1986;Orlando-Mathur and Kennedy, 1993). Chymase and tryptase are mast-cell-specific enzymes, and it is noteworthy that mast cells are present in endometrium throughout the cycle, and have also been impli¬ cated in decidualization in rodents (De Feo, 1967;Finn, 1986;Shelesnyak, 1986 (Mulholland et al, 1992) (Colombatti et al, 1989;Bonaldo et al, 1990a;Doliana et al, 1990 (Carson et al, 1988 (Kielty et al, 1992b), type I collagen (Chu et al, , 1990, decorin (Bidanset et al, 1992) and also with cell surfaces Kielty et al, 1992c).…”

S100A8: emerging functions and regulation

“…However, homozygous null embryos contain greater numbers of cells of maternal genotype that were detected both by polymerase chain reaction, and by using mothers systemically expressing a nuclear lacZ transgene. Given that the decidual reaction to embryo implantation is essentially a form of acute inflammation [90][91][92], it is proposed that S100A8 may have an immunoregulatory role and so contribute to the regulation of the fetal-maternal interaction. Its absence thus allows infiltration by maternal cells, a process eventually manifesting as resorption.…”