A Neurophysiologic Hypothesis for the Reactions to Hypoglycemia and Hyperglycemia

Robert E. BUCKLEY
1966 Neurologia medico-chirurgica  
The strange combinations of symptoms, complaints, and results which have been associated with changes in the blood suger has long provided us with both paradoxes and problems. It is easier, perhaps, to accept the neurophysiologic changes associated with hyperglycemia than hypoglycemia, since a metabolite is being added to the brain which might be expected to increase its activity in some way; but this rationalization cannot be used to explain the effects of hypoglycemia. It is paradoxical that
more » ... s paradoxical that reduction of glucose which should decrease the metabolic activity of the brain seems to cause a stimulation of it. The most basic and simple answer for this dilemma is a proposal that a nega tive feed-back circuit is the one which is first interfered with, so that the apparent stimulation caused by hypoglycemia results from the areas which can manifest their basic and intrinsic activity when an inhibitory force has been removed. Such a circuit has been described in the gluco-receptor mechanism of the hypothalamus and the control effect which it has to regulate food intake'). A description of this circuit, and a review of the effect which changes in blood suger have on the im mediately adjacent nuclei leads to the hypothesis of several negative feed-back circuits which are related to the activity of the ventromedial nucleus of the hypothalamus. The medial hypothalamus contains a "satiety center" which is activated by elevations of blood sugar to inhibit the function of a lateral hypothalamic area "feeding center" . This will lead to a stopping of food intake. Destruction of the evntromedial nucleus will diminish the activity of this "satiety center", and it can no longer inhibit the lateral hypothalamic area. These animals develope hyper phagia and become obese. Destruction of the lateral area so markedly inhibits the drive for food intake that animals may starve themselves to death. The location of the hypothalamic nuclei which are parts of the glucoreceptor mechanism have been found by poisoning the animals with gold Thioglucose. As long as glucose is a part of the molecule there is damage inflicted to the ventromedial nucleus, the arcuate nucleus, and occasionally the preoptic nucleus is involved. When similar compounds which do not include glucose in the molecule, such as gold Thioglycerol
doi:10.2176/nmc.8.1 fatcat:g5r3m26s3jcj5aufmqmuifh46u