Effect of Orexin Infusion into Third Ventricle on the Metabolic Parameters in the Goats Fed Low Energy Levels in Diets

The goal of this study was to determine whether orexin affects the mean plasma concentrations of metabolic parameters such as thyroxine (T4), triiodothyronine (T3), Growth Hormone (GH), insulin, glucagon, glucose, fatty acid and urea in the goats fed different energy content in diets. Sixteen goats were randomly divided into 4 groups. Animals in group 1 and 2 were fed 100% and animals in groups 3 and 4 were fed 50% energy content in diet for 20 days. After 20 days, animals in groups 1 and 3 received daily infusion of 1 μg orexin and groups 2 and 4 received daily infusion of 2 μg orexin into their third ventricle for 5 days. Lower dietary energy intake and infusions of 1 and 2 μg orexin significantly (p<0.01) decreased the mean plasma concentrations of T3, T4, insulin and glucose and significantly (p<0.01) increased the mean plasma concentrations of GH, glucagon, fatty acid and urea of the animals in groups 3 and 4. The results of this experiment indicated that orexin may negatively affect the T3, T4, insulin and glucose and increase GH, glucagon, fatty acid and urea in the goats with negative energy balance, but not in those with the positive energy balance.