A reexamination of the hypoglycemia-aggression hypothesis in laboratory mice

The suggestion of a clinical link between hypoglycemia and aggression has been recently encouraged by the work of Virkkunen and others. Modern techniques have impressively established a correlation between reactive hypoglycemia (low blood sugar levels engendered by stimulation of endogenous insulin secretion) and hostility as expressed in a variety of situations. It is not surprising that blood sugar levels influence behavior, as the brain is entirely dependent on glucose reaching it via the vascular system. In spite of this impressive link, there are remarkably few successful studies involving the effects of manipulating glucose levels on fighting in infrahuman animals. As there have been several methodological developments in this area it was thought appropriate to reinvestigate such phenomena in mice. The effects of injected bovine insulin and glucose were assessed using an ethopharmacological methodology applied to social encounters by isolated male Swiss mice with docile anosmic opponents. Although manipulation of blood glucose levels did not consistently change attack or defensive behavior, these treatments did modify aspects of the interactions.