Prolonged fasting or clonidine can restore the defective growth hormone secretion in old dogs

Age-related changes in GH secretion were studied in the dog. In preliminary experiments, administration of GH-relasing hormone (GHRH-40, 2 μg/kg, iv) or the α 2 -adrenoceptor agonist clonidine (4 μg/kg, iv) elicited significantly higher plasma GH rises in 3 to 4 years old than in 10 to 14 years old beagle dogs