Administration of bovine, porcine and equine growth hormone to the horse: effect on insulin-like growth factor-I and selected IGF binding proteins.

The research article discusses a study conducted on Thoroughbred horses to investigate the effects of administering different types of growth hormone, specifically equine, bovine, and porcine. The aim of the research was to identify potential markers that could indicate the misuse of these hormones in horses, with insulin-like growth factor I (IGF-I) emerging as the most promising.

Methodology and Outcome of the Research

• The study featured bio-medical experiments conducted on Thoroughbred geldings, aged between 3 and 5 years. The horses were administered with equine, bovine or porcine variants of recombinant growth hormone (GH) at doses recommended by experts.
• Porcine GH administration resulted in severe injection-site reactions in the horses, and thus, it had to be concluded ahead of schedule.
• The outcomes of this treatment with the different types of GHs were monitored by examining the serum concentration of several protein markers associated with GH. Specifically, insulin-like growth factor-I (IGF-I) was found to be a promising marker, showing an increase up to 270% of the base concentration after administration of equine GH.
• IGF-I was found to take a longer time to return to base concentration than GH itself, indicating that an elevated concentration of IGF-I could be a good marker to detect the abuse of GHs.

Significance of the Findings

• The finding that porcine GH induced severe injection site reactions suggests it is not a suitable treatment option in horses.
• The discovery of a potential new marker, IGF-I to indicate GH misuse is a major contribution of this research paper.
• The potential use of IGF-I as a GH administration indicator extends beyond Thoroughbred geldings, potentially being applicable to a variety of horses and other equine species as well.
• The research also provides significant insight on the behavior of specific proteins, like IGF-I and IGFBP-3, in response to GH administration in Thoroughbred horses, which might prove useful in understanding the biological mechanism of action and regulation of growth hormones.

Observations Beyond the Study Population

• Importantly, from a population of over 2000 Thoroughbred horses across three continents, it was observed that the concentration of IGF-I resulting from GH administration significantly exceeded normal natural concentrations.