Long-term progestin contraceptives (LTPOC) induce aberrant angiogenesis, oxidative stress and apoptosis in the guinea pig uterus: A model for abnormal uterine bleeding in humans

Abstract

BackgroundIrregular uterine bleeding is the major side effect of, and cause for, discontinuation of long-term progestin-only contraceptives (LTPOCs). The endometria of LTPOC-treated women display abnormally enlarged, fragile blood vessels (BV), decreased endometrial blood flow and oxidative stress. However, obtaining sufficient, good quality tissues have precluded elucidation of the mechanisms underlying these morphological and functional vascular changes.MethodsThe current study assessed the suitability of the guinea pig (GP) as a model for evaluating the uterine effects of LTPOC administration. Thus GPs were treated with a transdermal pellet for 21 days and examined for endometrial histology, angiogenic markers as well as markers of oxidative stress and apoptosis.Results and DiscussionWe now demonstrate that GP uteri were enlarged by both estradiol (E2) and medroxyprogesterone acetate (MPA) (p < 0.001). Effects of MPA on uterine weight differed significantly depending on E2 levels (p < 0.001), where MPA opposed the E2 effect in combined treatments. Angiogenesis parameters were similarly impacted upon: MPA alone increased BV density (p = 0.036) and BV average area (p = 0.002). The presence of E2 significantly decreased these parameters. These changes were associated with highly elevated of the lipid peroxidation product, 8-isoprostane (8-isoP) content in E2+MPA-treated and by nuclear 8-OH-deoxyguanosine (8oxoG) staining compared to all other groups (p < 0.001). Abnormalities in the E2+MPA group were consistent with chromatin redistribution, nuclear pyknosis, karyolysis and increased apoptosis as observed by a marked increase in TUNEL labeling.ConclusionsLTPOC exposure alters endometrial vascular and tissue morphology consistent with oxidative stress and apoptosis in a complex interplay with endogenous estrogens. These findings are remarkably similar to in vivo change observed in the human uterus following LTPOC administration. Hence, the GP is an excellent model for the study of LTPOC effects on the uterus and will be extremely useful in determining the mechanistic pathways involved in this process which cannot be conducted on humans.

Thrombin impairs human endometrial endothelial angiogenesis; implications for progestin-only contraceptive-induced abnormal uterine bleeding

“…Therefore, uncovering the detailed role of CSPG4 in progestin-only contraceptive-induced aberrant endometrial angiogenesis will require future studies using pericyte-HEEC as well as HESC-HEEC co-cultures in view of the crucial role played by CSPG4 in such cell to cell interactions [15]. These studies will be augmented by investigating the impact of thrombin on HESC-HEEC and pericyte-HEEC interactions and extended by including studies using our previously published guinea pig model [6] to investigate the effect of thrombin inhibitors on contraceptiveinduced vascular changes that contribute to AUB. Newly available direct oral anti-coagulants, which include direct thrombin inhibitors (dabigatran, etexilate) and direct factor Xa inhibitors (rivaroxaban and apixaban) that limit new thrombin generation are promising therapeutic agents [40,41] for evaluation in a clinical trial aimed at counteracting AUB caused by administration of progestin-only contraceptives such as DMPA.…”

“…Previously, we demonstrated that progestin-only contraceptive treatment reduces uterine blood flow, which elicits endometrial hypoxia (HX)/reperfusion and reactive oxygen species (ROS) generation in women or guinea pigs [5,6]. At bleeding sites, these changes are accompanied by enhanced expression by decidualized human endometrial stromal cells (HESCs) of tissue factor, which promotes hemostasis via thrombin generation [4].…”

Long-acting progestin-only contraceptives impair endometrial vasculature by inhibiting uterine vascular smooth muscle cell survival

“…Our previous studies (8,9) demonstrated that, as in human endometria, LAPC administration to GPs results in such endometrial vascular changes as focal hemorrhage, increased oxidative stress, high apoptotic indices, and elevated lipid peroxidation. Similarly, as in endometria of women receiving Depo, the present study confirmed reduced numbers of αSMA (+) cells and decreased VSMC Fig.…”

“…The endometria of women receiving LAPCs contain elevated levels of VEGF and angiopoietin-2 (Ang-2) (4). Like women, the guinea pig (GP) exhibits spontaneous estrous cycling and hemochorial placentation (5)(6)(7) and is a relevant animal model to study LAPCinduced AUB (1,(8)(9)(10). In humans and GPs, this hyperangiogenic milieu creates endometria displaying superficial, irregularly distributed enlarged, thin-walled capillaries and venules (2,9,10).…”

Effects of Etonogestrel Treatment in the Reproductive Organs and Uterine Arteries of Nonoophorectomized Guinea Pigs

“…For example, we evaluated the separate and interactive effects of E2 and MPA on GP-endometrial weight, vascular morphology, oxidative stress, and apoptosis on oophorectomized GPs treated with hormones for 21 days. 14 We observed GP uteri to be enlarged by both E2 and MPA. Of note, MPA alone increased blood vessel density average area, while E2 significantly decreased this parameter.…”