PSX-A-3 - Late-Breaking: Analysis of serum chemistry for metabolic function in GnRH-II receptor knockdown and littermate control boars

Pigs are the only livestock species encoding functional proteins for both the second form of gonadotropin-releasing hormone (GnRH-II) and its receptor (GnRHR-II), which are uniquely expressed in reproductive and non-reproductive tissues. To examine the physiological role of the GnRH-II/GnRHR-II system, we produced a swine line with reduced endogenous levels of GnRHR-II (GnRHR-II KD); males exhibit 70% diminished testicular GnRHR-II mRNA levels and 82% reduced circulating testosterone concentrations. Given that testosterone impacts metabolism, blood was collected from GnRHR-II KD (n = 5) and littermate control (n = 5) boars via indwelling jugular catheters, with serum isolated and subjected to veterinary diagnostic panels for metabolic analyte examination (PhysLab, Lincoln, NE). Statistical analyses utilized the MIXED procedure of SAS; the model included line as fixed and litter as random effects. Creatine kinase and blood urea nitrogen (BUN):creatinine ratios were elevated, creatinine was reduced (P < 0.01), and thyroxine tended to be decreased (P < 0.10) in GnRHR-II KD compared with control boars. Glucose, BUN, amylase, and lipase levels were not different. Liver products differed in transgenic versus control boars; levels of lactic dehydrogenase, aspartate and alanine aminotransferases (AST; ALT), and gamma-glutamyl transpeptidase were higher, whereas AST:ALT ratios, total protein, albumin, and globulin levels were lower (P < 0.05) in GnRHR-II KD boars. Albumin:globulin ratios and bilirubin (total and direct) did not differ. Additionally, serum cholesterol was decreased (P < 0.05), non-high density lipoproteins (HDLs) and low density lipoproteins (LDLs) tended to be decreased (P < 0.10), and triglycerides, HDLs, and cholesterol:HDL ratios did not differ between GnRHR-II KD and control males. These data suggest metabolic disruption in GnRHR-II KD boars, which may be due to suppressed gonadal steroidogenesis or ubiquitous knockdown of GnRHR-II expression. Supported by USDA/NIFA AFRI (2017-67015-26508) and Hatch Multistate (NEB-26-244) funds. USDA is an equal opportunity provider and employer.