Location: Livestock Bio-Systems
Project Number: 3040-31000-095-008-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Apr 1, 2017
End Date: Mar 31, 2021
The pig is one of just a few mammalian species that produce a functional GnRH-II receptor. Preliminary study from our laboratory revealed that GnRH-II receptor is present on specialized cells in the testis that are important for production of steroid sex hormones and sperm production. The long-term goal of the current proposal is to enhance understanding regarding the biological role of the porcine GnRH-II receptor in reproductive function and utilize this knowledge to improve fertility in swine. The specific objectives of the proposal are: 1. Partition the autocrine/paracrine pathways associated with LH-independent GnRH-II stimulation of testosterone production; 2. Identify signaling pathways and potential downstream targets resulting from GnRH-II binding to its cognate receptor in testicular tissue of the boar; 3. Determine how GnRH-II and its receptor influence spermatogensis and/or sperm function and fertility. ARS scientists will be involved in all three objectives.
The approach will be to use a transgenic line of pigs that the University of Nebraska has developed. These pigs over-express a small hairpin RNA specific for the GnRH-II receptor that eliminates transcritional expression of the GnRH-II receptor gene. A series of in vivo endocrine studies in mature boars will be paired with in vitro studies using testicular cultures to understand the molecular mechanisms through which GnRH-II receptor regulates testicular function. Hormone assays, RNA sequencing and cell signaling arrays will be used. An additional set of experiments will evaluate how sperm function is regulated by GnRH-II and what consequences result for fertility. The approach will be to quantify concentrations of GnRH-II, which activates the GnRH-II receptor on sperm, in seminal plasma from boars used for artificial insemination at USMARC and determine how the concentrations of GnRH-II relate to fertility.