MELATONIN SUPPRESSES HYPERGLYCEMIA CAUSED BY INTRACEREBROVENTRICULAR INJECTION OF 2-DEOXY-D-GLUCOSE IN RATS

To elucidate the role of melatonin (MT), we examined the effects of in tracranial injection of MT and an MT-antagonist (S20928) on the hyperg lycemic response to intracranial injection of 2-deoxy-D-glucose (2DG) in rats. The hyperglycemic and hyperglucagonemic responses caused by i ntracerebroventricular injection of 2DG were inhibited by intracerebro ventricular co-injection of MT, but enhanced by coinjection of the MT- antagonist. Intraperitoneal injection of MT also inhibited the hypergl ycemic response, though the inhibition seemed to be less than that aft er intracranial injection of MT. These results suggest that MT plays a n endogenously suppressive role in the hyperglycemia caused by 2DG, po ssibly through a brain site. (C) 1997 Elsevier Science Ireland Ltd.