Changes of plasma glucose and insulin during defense reactions in monkeys

Changes of plasma glucose and immunoreactive insulin (IRI) were measured during defense reactions elicited by electrical stimulation of the lateral hypothalamus in 12 unanesthetized rhesus monkeys adapted to chronic restraint in primate chairs. When hypothalamic stimulation was sufficient to produce marked behavioral excitement, plasma glucose approximately doubled within 15 min and remained elevated for the hour of stimulation. During the first 30 min of the elicited hyperglycemia, plasma IRI increased slightly, but less than expected relative to the glycemic stimulus. Despite the sustained hyperglycemia during the second 30 min of stimulation, plasma IRI returned to control values. The hyperglycemia during vivid defense reactions was abolished or greatly reduced in two adrenalectomized monkeys maintained on cortisone, suggests suggest that epinephrine is a major mechanism for acute hyperglycemia in monkeys. The hyperglycemia appeared to be related to the behavioral excitement of hypothalamic stimulation because when excitement was slight during stimulation of threshold intensity, or when excitement was prevented by pentobarbitol anesthesia, hyperglycemia was slight or was not observed. Inhibition of IRI during emotional hyperglycemia tends to divert glucose from the insulin dependent skeletal muscles and to conserve glucose for the central nervous system.