“
“Ovulation is characterized as a sequence of events in a responsive preovulatory follicle after a luteinizing

hormone (LH) surge [12] and [28]. This event is controlled by a complex interaction of factors, including endocrine mechanisms, cellular messengers, proteases, cinases and activating enzymes and has been compared to an inflammatory response [12] and [28]. The kallikrein–kinin system (KKS) is an important mediator of inflammatory responses acting Dinaciclib nmr on vasodilatation, activation and inactivation of proteases, stimulation of prostaglandin biosynthesis as well as induction of smooth muscle contractility [3] and [24]. Kininogen (KNG) is a precursor protein of the KKS; plasma kallikrein uses KNG as a substrate to generate bradykinin while tissue kallikrein liberates kallidin that is cleaved to the bradykinin [3] and [11]. Transmembrane Transporters modulator Bradykinin is a nonapeptide kinin, the main mediator of KKS responses [3] and [8]. This system acts through two types of receptors, type 1 (B1R) and

type 2 receptor (B2R). Therefore, the ovulation resembles an inflammatory process and the KKS is involved in the inflammatory function. This system has been suggested as a possible important mediator of the ovulatory process [5], [16], [17] and [18]. Despite the increasing evidences on the role of the KKS in mammal ovaries, little is known about the regulation of these components at distinct ovarian compartments, mainly in monovulatory species. Additionally, the intrafollicular factors that initiate and control the ovulatory process are not well understood [13]. Thus, the knowledge on this system role during the ovulatory process can allow a better control of physiological functions to be applied to reproduction biotechnology and infertility treatments. The purpose of this study is to characterize the presence and regulation of some of the KKS components during the bovine ovulation process.

Twenty-seven cyclic beef cows were pre-synchronized to obtain a GnRH responsive follicle (≥12 mm; [30]) at the beginning of the experiment according to a previous study [13]. Briefly, females that had ≥12 mm pre-ovulatory follicles on Day 10, were administered GnRH analog (Gonadorelin, 100 μg IM, Profertil®, Tortuga, Brazil) and the ovaries were removed 0, 3, 6, 12 and 24 h after the GnRH, by colpotomy Clomifene in standing position [10]. After the ovariectomy, follicular fluid, granulosa and theca cells were collected and stored conform described first [29]. All procedures involving animals performed in this experiment were approved by the Ethics and Animal Welfare Committee, Universidade Federal de Santa Maria, protocol number 23081.007716/2010-61. Total RNA was extracted using Trizol (theca cells) or silica based protocol (granulosa cells; Qiagen, Mississauga, Canada) according to the manufacturer’s instructions and was quantified by absorbance at 260 nm.