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Substances: Equine Growth Hormone (eGH)

Growth hormone (or somatotropin) is a protein of 191 amino acids synthesised in the pituitary gland of all animals (including humans).

Growth hormone (GH) is released in multiple pulses throughout the day and as such production levels vary dependent upon both individual and environmental factors. Generally a marked decrease in production of GH is observed in aging animals.

Primarily GH promotes growth and regulates metabolism in a wide range of species. It acts on various cell types both directly and indirectly via stimulating the release of insulin like growth factor (IGF-1). For this reason the effects of GH administration are diverse. Its use as a therapeutic agent vary from human GH (hGH) administration in children with dwarfism to equine GH (eGH) administration in aging horses.

A synthetic form of eGH can be produced via recombinant DNA technology. Though it has one additional methionone residue, recombinant eGH is identical to pituitary-derived equine somatotropin. Recombinant eGH is intended for use, in horses only, as an aid to improve the nitrogen balance (as a negative nitrogen balance in aged horses is thought to lead to a decline in body condition and muscle tone). The Australian Pesticides and Veterinary Medicines Authority strictly regulate the supply of this substance for it's intended purpose.

Anecdotal evidence suggests that athletes seeking to illegally enhance sporting performance may choose to ignore the potential adverse health effects that could be encountered from using a substance intended for use in another species.

The similarity of chemical structure between the human and equine forms of GH is high and as such eGH is prohibited in sporting competition. However appropriate clinical trials have not been conducted to determine the activity of eGH in humans. Such trials involving the administration of cross species hormones are unlikely to ever be approved by any ethics committee.

Side Effects

Administration of a foreign substance will induce the production of anti-bodies to that substance. This could manifest in the form of site of injection reactions or potentially fatal reactions such as anaphylactic shock.

Status in Sport

Equine growth hormone is prohibited both in and out-of-competition under the World Anti-Doping Code 2007 Prohibited List (effective from 01/01/07).

 

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