title: Identification of gonadotropin-releasing hormone metabolites in greyhound urine.
abstract: Gonadotropin-releasing hormone (GnRH) is a 10-residue peptide hormone that induces secretion of luteinizing hormone (LH) and follicle-stimulating hormone into the blood from the pituitary gland. In males, LH acts on the testes to produce testosterone. The performance-enhancing potential of testosterone makes administration of exogenous GnRH a concern in sports doping control. Detection of GnRH abuse is challenging owing to its rapid clearance from the body and its degradation in urine. Following recent investigations of GnRH abuse in racing greyhounds in New Zealand, we carried out a GnRH administration study in greyhounds in an attempt to identify GnRH metabolites that might provide more facile detection of GnRH abuse; little information is available on in vivo metabolites of exogenous GnRH in any species and none in dogs. We identified three C-terminal GnRH metabolites in urine: GnRH 5-10, GnRH 6-10, and GnRH 7-10. These metabolites and intact GnRH, which was also detected in urine, were all excreted over a 1-3 h period after GnRH administration. Two of the GnRH metabolites - GnRH 5-10 and GnRH 6-10 - were more stable in urine than intact GnRH offering improved potential to detect GnRH administration. Copyright © 2017 John Wiley & Sons, Ltd.
authors.affiliation: New Zealand Racing Laboratory Services Ltd, PO Box 19514, Avondale, Auckland, 1746, New Zealand.
authors.forename: David
authors.identifier: http://orcid.org/0000-0001-8969-5192
authors.initials: D
authors.lastname: Palmer
authors.affiliation: New Zealand Racing Laboratory Services Ltd, PO Box 19514, Avondale, Auckland, 1746, New Zealand.
authors.forename: Katie
authors.initials: K
authors.lastname: Rademaker
authors.affiliation: New Zealand Racing Laboratory Services Ltd, PO Box 19514, Avondale, Auckland, 1746, New Zealand.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Martin
authors.affiliation: Racing Integrity Unit, Private Bag 17902, Greenlane, Auckland, 1546, New Zealand.
authors.forename: Joan
authors.initials: J
authors.lastname: Hessell
authors.affiliation: New Zealand Racing Laboratory Services Ltd, PO Box 19514, Avondale, Auckland, 1746, New Zealand.
authors.forename: Rob
authors.initials: R
authors.lastname: Howitt
mesh_terms: D000818:Animals; D004285:Dogs / Q000378:metabolism / Q000652:urine*; D004300:Doping in Sports; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000378:metabolism / Q000652:urine*; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D009520:New Zealand; D058573:Performance-Enhancing Substances / Q000008:administration & dosage / Q000378:metabolism / Q000652:urine*; D052616:Solid Phase Extraction / Q000379:methods; D015813:Substance Abuse Detection / Q000379:methods*
chemical_list: D058573:Performance-Enhancing Substances; D007987:Gonadotropin-Releasing Hormone
keywords: gonadotropin-releasing hormone; greyhound; mass spectrometry; metabolites; urine