Changes in lateral hypothalamic neuronal activity accompanying hyper- and hypoglycemias.

Blood glucose level and forebrain unit activity were simultaneously recorded in rats anesthetized with a ketamine IV infusion. Slight and transient fluctuations in glycemia, occurring either spontaneously or after IV injections of glucose or phlorizin, were observed. The spike frequency of more than 1/3 of the neurons tested in the lateral hypothalamic area was affected by these fluctuations. A majority of the responsive cells displayed either an activation during hypoglycemia or a depression during hyperglycemia. These neurons might mediate the effects of a drop in blood glucose on either meal initiation or neuroendocrine or autonomic events related to nutritional functions.