Investigations on the Endometrial Response to Intrauterine Administration of N‐Acetylcysteine in Oestrous Mares

Abstract

In mares, mating-induced persistent endometritis contributes to low fertility. The condition is in part related to delayed clearance of mucus accumulated within the uterine lumen. The objective of this study was to investigate the endometrial response of healthy mares to intrauterine (i.u.) treatment with N-acetylcysteine (NAC). Oestrous mares (n = 12) were randomly assigned to a treatment (TM) or control (C) group and received an i.u. infusion of 5% NAC and saline (total volume 140 ml), respectively. Endometrial biopsies were collected in five of the mares 24 h after treatment, in the remaining seven mares 72 h after treatment. Endometrial biopsies were evaluated for integrity of the luminal epithelium, number of polymorphonuclear neutrophils (PMN), staining for cyclooxygenase 2 (COX2), staining with Kiel 67 antigen (Ki-67), lectins and periodic acid-Schiff (PAS). The integrity of endometrial epithelial cells was not affected by treatment (no statistical differences between groups or times). At 24 h after treatment, the mean number of PMN in endometrial biopsies from NAC- and C-mares did not differ, but at 72 h after treatment, number of PMN was significantly higher (p < 0.05) in C (3.9 ± 0.6 PMN/field) compared with NAC-treated mares (2.3 ± 0.2 PMN/field). At 72 h after treatment, the intensity of staining for COX2 was significantly higher after saline than after NAC treatment (p < 0.05). In the epithelium, no differences in staining for the proliferation marker Ki-67 were seen with respect to time and treatment. Score for the lectin wheat germ agglutinin (WGA) was slightly higher in NAC-treated mares than in C-mares 72 h after treatment (p < 0.05). Score for PAS staining of mucus in deep uterine glands differed significantly between groups at 24 h after treatment (p < 0.05). The present study demonstrates that NAC does not adversely affect the endometrial function. Moreover, an anti-inflammatory effect on the equine endometrium was observed.

Preimplantation factor modulates acute inflammatory responses of equine endometrium

“…; Melkus et al . ); however, with each there are important drawbacks (LeBlanc ; Gores‐Lindholm et al . ; Woodward et al .…”

Update on endometritis therapy

“…Local treatment is well tolerated (Gores-Lindholm et al 2009, LeBlanc 2010, Melkus et al 2013) and therefore the preferred route of treatment is IU. Treatment of normal mares with 140 ml of 5 % NAC reduced inflammation: neutrophil numbers and intensity of staining for COX-2 were significantly lower at 72 h as compared to controls.…”

“…Pferdeheilkunde 32 (2016) 41 the endometrium (Melkus et al 2013). In the study of GoresLindholm et al (2009), 3 % NAC inhibited the oxidative burst of serum-derived neutrophils and reduced extracellular mucus thickness and staining intensity.…”

Die persistierende belegungsinduzierte Endometritis bei der Stute – ein nicht zu unterschätzender Grund für Fruchtbarkeitsstörungen

“…per os In eigenen Studien wurde N-Acetylcystein sowohl intrauterin als auch oral an gesunde Stuten während der Rosse gegeben. Es kam zwar zu keinen nennenswerten Einflüssen auf die Viskosität des Uterussekretes, allerdings zeigte sich, dass N-Acetylcystein deutliche entzündungshemmende Einflüsse auf das Endometrium hat [6,12]. …”