Glucose and endocrine responses to hypothalamic electrical stimulation in rats.

The effect of ventromedial (VMN) or basolateral (LHA) hypothalamic electrical stimulation on glucose and hormone production was examined in conscious and anesthetized male rats. Barbiturate treatment alone led to large increases of corticosterone and smaller but significant increases of glucose, insulin, and glucagon. When hypothalamic stimulation was combined with anesthesia, interactions between the hypothalamic sites and the awake-anesthetized conditions were observed. This was most evident with LHA placements, as awake rats exhibited mild hypoglycemia and hypoglucagonemia in response to low-level (approximately 10 microA rms) current, but no effects on these values were seen with VMN electrodes. With barbiturate anesthesia, the same level of stimulation led to severe hyperglycemia in both VMN and LHA rats and a mild hyperglucagonemia in the LHA group. No consistent effects of stimulation on immunoreactive insulin or corticosterone were detected at either hypothalamic site or in any anesthesia condition. The present results point out the important role anesthetics may play in studies defining functional aspects of the hypothalamus. Furthermore, our inability to elicit consistent autonomic responses with electrical stimulation, when compared with the effectiveness of both metabolic agents and pharmacologic stimuli, suggests that the sites integrating autonomic function may be diffusely distributed over the basal diencephalon.