The effect of electrical stimulation of the hypothalamus on continuously-monitored blood glucose levels.

The effects of hypothalamic stimulation on blood glucose levels were investigated in unanaesthetised rats with intracardiac catheters directly connected to a continuous glucose analyzer. Thirty sec of low level electrical stimulation produced hyperglycemia at 23 of the 34 sites stimulated. At the remaining 11 sites the electrical stimulation produced no changes in blood glucose levels. The hyperglycemia could be dissociated from the changes in motor activity produced by the stimulation. The highest probability of producing hyperglycemia was found at ventro-lateral sites although hyperglycemia was also observed after stimulation of dorsal and medial sites. Apart from this medio-lateral difference in the density of sites at which stimulation produced hyperglycemia, the effects were not well differentiated anatomically. In addition, in terms of latency, peak magnitude and duration of the hyperglycemia, stimulation of the various hypothalamic subdivisions appeared to be functionally equivalent. Thus with respect to hypothalamic involvement in the maintenance of blood glucose levels the present stimulation analysis suggests a medio-lateral functional similarity which is very different from the medio-lateral reciprocity of lesion effects on ingestive behaviour and body weight.