Restraint stress delays endometrial adaptive remodeling during mouse embryo implantation

Abstract

We showed previously in mice that restraint stress reduces the number of embryo implantation sites in the endometrium. Here we hypothesized that the uterine microenvironment is altered by restraint stress and consequently is sub-optimal for embryo implantation. On embryonic day 1 (E1), 60 of 154 pregnant CD1 mice underwent restraint stress (4h), repeated daily to E3, E5 or E7 (n = 10 mice per group). Restraint stress decreased food intake and suppressed body weight gain on E3, E5 and E7. Restraint stress decreased the actual and relative weight (percent body weight) of uterus and ovary on E5 (by 14.9%, P = 0.03; 16.1%, P = 0.004) and E7 (by 16.8%, P = 0.03; 20.0%, P = 0.01). Morphologically, restraint stress decreased relative endometrial area (by 8.94-18.8%, P = 0.003-0.021) and uterine gland area (by 30.6%, P < 0.01 on E3 and 44.5%, P < 0.01 on E5). Immunohistochemistry showed that restraint stress decreased microvessel density (by 12.9-70.5%, P < 0.01) and vascular endothelial growth factor expression (by 14.6-45.9%, P = 0.007-0.02). Restraint stress decreased by 32.4-39.8% (P = 0.002-0.01) the mean optical density ratio for proliferating cell nuclear antigen/terminal deoxynucleotidyl transferase dUTP nick end labeling. Methyl thiazolyl tetrazolium assay showed a dosedependent decrease in proliferative activity of endometrial stromal cells (from 52 of 154 pregnant E5 control mice) incubated with H 2 O 2 (100-1000 μM) in vitro. These findings supported the hypothesis that restraint stress negatively influences endometrial adaptive remodeling via an oxidative stress pathway, which resulted in fewer implantation sites. Stress Downloaded from informahealthcare.com by Nanyang Technological University on 08/26/15 For personal use only. Stress Downloaded from informahealthcare.com by Nanyang Technological University on 08/26/15 For personal use only. Stress Downloaded from informahealthcare.com by Nanyang Technological University on 08/26/15 For personal use only. Stress Downloaded from informahealthcare.com by Nanyang Technological University on 08/26/15 For personal use only. Stress Downloaded from informahealthcare.com by Nanyang Technological University on 08/26/15 For personal use only.

Restraint stress induces uterine microenvironment disorder in mice during early pregnancy through the β2-AR/cAMP/PKA pathway

“…Therefore, the uterus may be an important organ for studying reproductive stress exposure as a form of psychological stress. Additionally, in the present study, we found that restraint stress affected the balance between oxidation and antioxidation [10], as well as the balance between proliferation and apoptosis, under restraint stress in early pregnancy [21]. Recently, psychological stress has attracted worldwide attention.…”

“…Primary mouse uterine stromal cells from E5 pregnant mouse uteri were isolated as described in a related study [21]. Briefly, uterine tissue from E5 mice was removed from the fat tissue, cut longitudinally, and washed with Hanks' balanced salt solution (HBSS, containing 100 U/mL penicillin and 100 µg/mL streptomycin).…”

“…During pregnancy, the balance between cell proliferation and death is crucial for successful embryo implantation and the maintenance of pregnancy [20]. In our previous studies, restraint stress was shown to disturb the adaptive reconstruction of the endometrium during implantation in maternal mice [21] and to be associated with oxidative stress-induced immune dysfunction and an imbalance between cell proliferation and apoptosis [10,21]. β 2 -AR activates adenylyl cyclase (AC) by triggering the coupling of the receptor to Gs.…”

A novel and compact review on the role of oxidative stress in female reproduction

“…In addition, restraint stress markedly decreased the CD3 + CD4 + T/CD3 + CD8 + T cell ratio. Additionally, antioxidant ability was compromised, and the concentration of MDA was increased [ 86 ]. Moreover, restraint stress reduced the weight of the uterus and ovary and the intake of food with reduction in weight, while the relative endometrial area and uterine gland area were reduced after restraint stress.…”

Stress and the HPA Axis: Balancing Homeostasis and Fertility

“…Restraint stress in pregnant mice significantly reduced the pregnancy rate and average litter size of mice as compared to controls, attributed in part to reduced number of implantation sites [ 46 ]. Decreased endometrial cell proliferation, vascular endothelial growth factor expression, and microvessel density were found in mated female mice exposed to restraint stress, which may provide some insight into the mechanisms by which restraint stress negatively influences the uterine environment [ 47 ]. Auditory stress on female mice has also been reported to have adverse effects on uterine receptivity [ 48 ].…”