Anti-oxidative and anti-inflammatory activities of adrenomedullin (ADM) in the rat uterus

Abstract

Adrenomedullin (ADM) is a multifunctional peptide that signals through a Gprotein -coupled receptor. Previous studies in our laboratory showed that in rats, the genes encoding for ADM peptide, Adm and its receptor omponents are expressed in male accessory sex glands (ASGs), including the prostate, the coagulating gland and the seminal vesicle while ADM is found in both the tissues and the secretions of these ASGs. The high level of ADM found in post coital uterine flushing suggests that this hormone may play a possible role in reproductive physiology, especially in the female reproductive tract. The aim of this study is to investigate the functional roles of ADM in the female reproductive tract. After pretreatment with 100nM ADM for 30 min, the reactive oxygen species (ROS) level generated by 1lM hydrogen peroxide in isolated endometrial epithelial cells were measured by the fluorescence intensity method using 5-(and-6)-chloromethyl-2’,7’-dichlorodihydrofluorescein diacetate, acetyl ester (CM-H2DCFDA). We found that incubating with ADM significantly decreased the hydrogen peroxide-induced ROS level in endometrial epithelial cells, suggesting that ADM secreted by the ASGs may protect the sperm against ROS generated in uterus. A similar decrease in ROS in epithelial cell was also observed when treated with post coital uterine flushings, suggesting the ADM from seminal plasma can protect uterine epithelial damage from ROS. ADM has been shown to be an anti-inflammatory agent that acts through nitric oxide system. To find out the anti-inflammatory effect of ADM on the rat uterus, uterine tissue was cultured with ADM for 4 h and the levels of tumor necrosis factor-alpha(TNF-alpha) in the culture media were measured using enzyme-linked immunosorbent assays (ELISA).- Treatment with ADM significantly decreased TNF-alpha production suggesting that ADM may play an anti-inflammatory role in the uterus. The present study provides evidence for a role of ADM in the seminal plasma in ROS production and the maternal immune response in the uterus. This study is supported by a grant from the Research Grant Council of Hong Kong SAR (GRF775908).