Abstract
Summary
Although the phenomenon of conditioned hypoglycemia is now well established, little is known about its mechanism. The present experiments lead to the conclusion that the mechanism involves a release of insulin: Experiment 1 showed that rats given an injection of streptozotocin, a drug which destroys the beta cells of the islets of Langerhans, did not show a conditioned hypoglycemia, whereas rats given only the vehicle for the streptozotocin did; and in experiment 2, blood drawn from conditioned rats just before the conditioned hypoglycemia would normally occur showed greater insulinlike activity than blood drawn from control rats. These results demonstrate a conditioned release of some hypoglycemic agent that depends upon the integrity of the beta cells. A neural control over release of insulin must be inferred to explain them.
This study was supported by the USPHS Training Grant No. 5TO1 GM 00666. Thanks are due to Dr. Clara A. Muehlbaecher and to Dr. Daniel Porte, Jr. for their helpful comments; to Jane Hajdu for the histological work; and to Dr. Raymond Pictet for supplying the streptozotocin.
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