Glucose and Osmosensitive Neurones of the Rat Hypothalamus

THE lateral hypothalamic region (LH) is generally referred to as the feeding centre of the brain in the regulation of food intake, and many authors consider the ventromedial hypothalamic nucleus (VMH) to be the satiety centre1. Various hypotheses have been put forward to explain how the cells of these centres are activated, and one of these is the glucostat theory1. The existence of hypothalamic chemoreceptors, such as those sensitive to the concentration of blood glucose, can be inferred from studies of single unit discharges induced by intravenous or intracarotid administration of various solutions2–4 and from work on selective gold thioglucose lesions5. It has, however, been impossible to determine which centre is activated or inhibited first or whether both centres are modulated directly by a change in the concentration of blood glucose, because of the reciprocal relations which exist between the activities of the VMH and the LH2,6. We report here the direct effects of glucose on individual cells of the VMH and LH, which we studied by means of electro-osmotic applications of glucose from micropipettes—the method used by Krnjević and Whittaker7 in other regions in the brain.