The Preliminary Study About the Involvement of Relaxine in Adverse Effect of Polychlorinated Biphenyls on Bovine Myometrial Contractions

Abstract

Polychlorinated biphenyls (PCBs) are a group of synthetic xenobiotics, which were used in lots of industrial applications. Two individual congers (PCB 153 and PCB 77) belong to the most prominent environmental contaminations among PCBs, but they have opposite type of configuration and therefore they can exert a different way of action. Since PCBs increased the force of myometrial contractions, in this work, their effect on myometrial sensitivity on inhibitor of myometrial contractions (relaxine, RLX) was studied.Bovine myometrial cells and strips, and luteal cell at 4-8 month of pregnancy, were obtained accidentally in commercial abattoir. They were treated by PCB 153 and PCB 77 and mRNA expression of RLX receptor in myometrial cells and contractions of myometrial strips as well as the secretion of progesterone (P4) and oxytocin (OT) from luteal cells, were measured under their effect.Both studied congeners decreased (P<0.05) the mRNA expression of RLX receptor in myometrium. Admittedly, both PCB 77 and 153 increased (P<0.05) the basal force of contractions, while RLX showed any effect on myometrial contractions. Studied PCBs increased also (P<0.05) secretion of P4 and OT from luteal cells.It is suggested that PCBs can decreased the sensitivity of myometrium on RLX but their direct effect on RLX function have to be further investigated. Keywords: Endocrine Disruption; Pregnancy; Uterus IntroductionPolychlorinated biphenyls (PCBs) are a group of synthetic, chlorinated aryl hydrocarbons, which were extensively used in lots of industrial applications, mainly in transformers, capacitors or as hydraulic fluids, heat exchange liquids as well as plasticizers and others [1]. Because of different degree of chlorination, there are possible up to 209 congeners of PCBs. Among them, 3,3 ' ,4,4 ' -tetrachlorobiphenyl (PCB 77) is one of the most abundant PCB congeners in human milk. This congener is a non-ortho chlorine substituted with coplanar configuration and appear to exert its toxic effects via interacting with the cytosolic aryl hydrocarbon receptor (Ahr). Hence is recognized also as dioxin-like PCBs [2]. Since PCB 77 can affect the cell also through estrogen [3] and glucocorticoid receptors [4], it is recognized as a significant environmental pollutant and endocrine disruptor [3] with a wide spectrum of way of action. Admittedly 2,2',4,4', 5,5'-hexachlorobiphenyl PCB 153 is also one of the most prominent environmental contaminants, but oppositely to PCB 77 is classified as di-ortho, non-coplanar, non-dioxin congener of PCBs [5] and is known to have rather estrogenic properties [6]. Even though PCBs production and use were banned in USA and Europe more than three decades ago, they are still measured in environment [7]. Due to their lipophilic nature and resistance for biodegradation, PCBs have been bio-accumulated in animal tissues [8], also in domestic animals [9,10]. Therefore PCBs have been also measured in food samples [11] and they can be mentioned as a serious health risk.Since PCBs accumulation in preg...