Growth Hormone, Insulin, and Glucose in Suckling, Weanling, and Mature Ruminants

Abstract

Experiments were designed to test growth hormone and immunoreactive insulin responses of goats and sheep at three stages of development to known stimulators of growth hormone release. Glucose, deoxyglucose, insulin, and arginine were injected intravenously into ruminants in which glucose utilization rates differed, and immunoreactive growth hormone and insulin, and glucose were measured in serum. Increased blood glucose was followed by increased serum growth hormone. Deoxyglucose injections increased glucose but decreased glucose utilization and increased growth hormone (most in suckling and least in mature ruminants). Insulin injections caused the most severe hypoglycemia in weanling ruminants, but there was no age-related difference in the growth hormone response as has been reported for humans. Arginine injections increased growth hormone and insulin in all groups although increases were least in the youngest animals. When compared with the pattern of responses previously reported, especially in mature primates, growth hormone responses to similar stimuli in mature ruminants were more sluggish and the peaks attained were lower. In ruminants intravenous glucose is a potent growth hormone stimulus whereas in primates it is a depressant. © 1971, American Dairy Science Association. All rights reserved.