title: Thyreotropic effect of human Chorionic Gonadotropin (hCG) in mares at estrus.
abstract: The beta-subunits of thyroid stimulating hormone (TSH) and human chorionic gonadotropin (hCG) share a high homology, just like the ectodomains of their receptors, do. As a consequence, hCG was shown to exert a thyrotropic action in humans and hamsters. This study aimed to investigate whether hCG, used to induce ovulation, displays a thyrotropic effect in the equine species too. Forty mares at estrus were divided in two groups; 20 were intravenously treated with sterile saline solution (NaCl 0.9%) (group A); 20 were intravenously treated with 4000 I.U. of hCG (group B). All the mares were artificially inseminated 24 hours after the administration of the drugs and underwent blood collection at estrus detection (T1), 2, 6, 24 hours later (T2, T3, T4), and 3 and 6 days later (T5, T6), in order to detect serum fT3 and fT4 concentrations. fT3 concentrations gave rise to similar and constant trends in the two groups, without any statistically significant difference, whereas fT4 concentrations declined in both groups, remaining statistically higher in group B than in group A for 48 hours (p < 0.05), thus accounting for a thyrotropic effect of hCG. Pregnancy rate was 70% in group B and 40% in group A, respectively. The higher success in the outcome of pregnancy may result from the immunomodulating and steroidogenic effects of hCG and from the higher levels of thyroid hormones observed in the hCG treated group.
authors.affiliation: Department of Animal Production, Faculty of Veterinary Medicine, University of Bari, Valenzano, Bari, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Rizzo
authors.forename: Maddalena
authors.initials: M
authors.lastname: Mutinati
authors.forename: Massimo
authors.initials: M
authors.lastname: Spedicato
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Minoia
authors.forename: Carmelinda
authors.initials: C
authors.lastname: Trisolini
authors.forename: Stefano
authors.initials: S
authors.lastname: Punzi
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Roscino
authors.forename: Felicita
authors.initials: F
authors.lastname: Jirillo
authors.forename: Raffaele
authors.initials: R
authors.lastname: Sciorsci
mesh_terms: D000818:Animals; D006063:Chorionic Gonadotropin / Q000008:administration & dosage*; D004971:Estrus / Q000097:blood / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D006736:Horses; D007315:Insemination, Artificial; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000097:blood / Q000187:drug effects / Q000276:immunology; D013972:Thyrotropin / Q000008:administration & dosage*; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*
chemical_list: D006063:Chorionic Gonadotropin; D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine