The effect of baclofen on growth hormone, thyroxine, and triiodothyronine in Holstein cows

In this research study, the effect of baclofen (GABAB receptor agonist) on mean concentration of growth hormone, thyroxine, and triiodothyronine was examined. For this purpose, twelve Holstein Cows were divided into four groups. Then, each cow received daily injection of 25, 50, 75, and l00 mg/kg of baclofen for a period of four days. Blood samples were daily collected at one time point for eight days. Growth hormone, thyroxine, and triiodothyronine concentrations of plasma samples were measured by RIA (Radioimmunoassay) method. The results showed that baclofen increased mean plasma concentration of growth hormone and thyroxine (p<0.01). In addition, low doses of baclofen decreased mean plasma concentration of triiodothyronine (p<0.05), while 100 mg/g of baclofen increased mean plasma concentration of triiodothyronine (p<0.05).