[Nervous mechanisms in the regulation of blood sugar]

The aim of this paper is to precise the involvement of the nervous system in blood glucose regulation. The relevant mechanisms, triggered by blood glucose changes (increase or decrease of glycemia), intervene through the control of pancreatic and surrenal hormone release on the one hand, and hepatic glucose synthesis on the other hand. The part of various efferents and afferents, sensory endings and central "glucosensitive" neurons was analyzed in different situations. 1) Hyperglycemia increases the activation of the pancreatic parasympathetic fibres and decreases that of the surrenal sympathetic fibres. Hypoglycemia elicits reverse effects in the two types of efferents. 2) Hyperglycemia produces an activation in hepatic efferent vagal fibres and thus an acceleration of glycogen synthesis. Reversely, hypoglycemia stimulates both the hepatic sympathetic efferents and the glucose release by the liver. 3) The gustative receptors and the gastro-intestinal glucoreceptors are stimulated by glucose, which produces an insulin release. 4) The various kinds of afferents modify the efferent control of blood glucose level, through the "glucosensitive" central neurons located in hypothalamic and medullary regions.