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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 #313406
Title: LH-independent testosterone secretion is mediated by the interaction between GNRH2 and its receptor within porcine testes

Author
item DESAULNIERS, AMY - University Of Nebraska
item CEDERBERG, REBECCA - University Of Nebraska
item MILLS, GINGER - University Of Nebraska
item FORD, JOHNY - Retired ARS Employee
item Lents, Clay
item WHITE, BRETT - University Of Nebraska

Submitted to: Biology of Reproduction
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/2015
Publication Date: 8/1/2015
Publication URL: https://handle.nal.usda.gov/10113/61428
Citation: Desaulniers, A.T., Cederberg, R.A., Mills, G.A., Ford, J.J., Lents, C.A., White, B.R. 2015. LH-independent testosterone secretion is mediated by the interaction between GNRH2 and its receptor within porcine testes. Biology of Reproduction. 93(2):45.

Interpretive Summary: Although often overlooked, fertility of boars has an important impact on reproductive efficiency of swine herds. Currently, 80% of swine producers in the United States utilize artificial insemination, requiring an estimated 30 million doses of semen every year. There is a critical need to understand testicular function to develop methods to improve semen production and quality. ARS scientists, in collaboration with researchers from the University of Nebraska, found that boars have a hormone receptor called gonadotropin-releasing hormone receptor 2 (GnRHR2). They discovered that GnRHR2 is localized to special cell types within the testicle and found that activating the receptor increased secretion of testosterone, which is important for sperm production. Continued examination of how GnRHR2 regulates testicular function in boars will ultimately result in improvements in production and quality of semen for increased fertility.

Technical Abstract: Unlike the classical gonadotropin-releasing hormone (GNRH1), the second mammalian isoform (GNRH2) is an ineffective stimulant of gonadotropin release. Species that produce GNRH2 may not maintain a functional GNRH2 receptor (GNRHR2) due to coding errors. A full length GNRHR2 gene has been identified in swine, but its role in reproduction requires further elucidation. Our objective was to examine the role of GNRH2 and GNRHR2 in testicular function of boars. We discovered that GNRH2 is more highly expressed in the testis than in the anterior pituitary gland or hypothalamus, corresponding to greater GNRHR2 levels in the testis versus the anterior pituitary gland. Moreover, GNRH2 is most abundant within the seminiferous tubules, whereas GNRHR2 is highly expressed on Leydig cells. A GNRH2 pretreatment of testis explant cultures elicited testosterone secretion similar to hCG stimulation. Treatment of mature boars with GNRH2 stimulated testosterone secretion similarly to GNRH1 treated males, despite minimal GNRH2-induced release of luteinizing hormone (LH). When pretreated with a GNRH1 antagonist (SB-75), subsequent GNRH2 treatment elicited low levels of testosterone secretion despite a pattern of LH release similar to the previous trial, suggesting that SB-75 inhibited testicular GNRHR2s. Given pigs lack testicular GNRHR1, these data may indicate that GNRH2 and its receptor are involved in autocrine or paracrine regulation of testosterone secretion. Notably, our data are the first to suggest a biological function of a novel GNRH2-GNRHR2 system in the testes of swine.