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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Livestock Bio-Systems » Research » Publications at this Location » Publication #416460
Research Project: Improving Lifetime Productivity in Swine using Systems Biology and Precision Management Approaches

Location: Livestock Bio-Systems

Title: Knockdown of gonadotropin-releasing hormone II receptor impairs ovulation rate, corpus luteum development, and progesterone production in gilts

Author
item DESAULNIERS, AMY - University Of Nebraska
item CEDERBERG, REBECCA - University Of Nebraska
item Lents, Clay
item WHITE, BRENT - University Of Nebraska

Submitted to: Animals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/13/2024
Publication Date: 8/14/2024
Citation: Desaulniers, A.T., Cederberg, R.A., Lents, C.A., White, B.R. 2024. Knockdown of gonadotropin-releasing hormone II receptor impairs ovulation rate, corpus luteum development, and progesterone production in gilts. Animals. 14. Article 2350. https://doi.org/10.3390/ani14162350.
DOI: https://doi.org/10.3390/ani14162350

Interpretive Summary: Failure of female pigs (gilts) to become pregnant and produce a litter is the main cause of culling females in swine industry and costs producers over $1500 for every culled gilt. The pig is one of the only mammals that produce a hormone called gonadotropin-releasing hormone 2 (GnRH2). This hormone and its receptor (GnRHR2) have a critical role in controlling reproduction in male pigs, but their role in regulating reproduction in gilts is completely unknown. To address this gap in knowledge, ARS scientist in collaboration with researchers from the University of Nebraska, examined the ovaries and measured reproductive hormones in a unique line of pigs that were genetically modified to produce less GnRHR2 and compared them to unmodified pigs. They found that the modified pigs had fewer ovulations and that their ovaries produced less progesterone, a critical hormone that promotes pregnancy. This research provides important new insights into factors that contribute to pregnancy in gilts. This new understanding is expected to lead to new ways to improve fertility and productivity of breeding gilts.

Technical Abstract: Reproduction is classically controlled by gonadotropin-releasing hormone (GnRH-I) and its receptor (GnRHR-I) within the brain. In pigs, a second form (GnRH-II) and its specific receptor (GnRHR-II) are also produced, with greater abundance in peripheral vs. central reproductive tissues. The binding of GnRH-II to GnRHR-II has been implicated in the autocrine/paracrine regulation of gonadal steroidogenesis rather than gonadotropin secretion. Blood samples were collected from transgenic gilts, with the ubiquitous knockdown of GnRHR-II (GnRHR-II KD; n = 8) and littermate controls (n = 7) at the onset of estrus (follicular) and 10 days later (luteal); serum concentrations of 16 steroid hormones were quantified by high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). Upon euthanasia, ovarian weight (OWT), ovulation rate (OR), and the weight of each excised Corpus luteum (CLWT) were recorded; HPLC-MS/MS was performed on CL homogenates. During the luteal phase, serum progesterone concentration was reduced by 18% in GnRHR-II KD versus control gilts (p = 0.0329). Age and weight at puberty, estrous cycle length, and OWT were similar between lines (p > 0.05). Interestingly, OR was reduced (p = 0.0123), and total CLWT tended to be reduced (p = 0.0958) in GnRHR-II KD compared with control females. Luteal cells in CL sections from GnRHR-II KD gilts were hypotrophic (p < 0.0001). Therefore, GnRH-II and its receptor may help regulate OR, CL development, and progesterone production in gilts.