Programme Hospitalier Recherche Clinique, Institut Pasteur, Inserm, French Public Health Agency.

Diabetic nephropathy represents a major complication of diabetes mellitus (DM), and the origin of this complication is poorly understood. Vasopressin (VP), which is elevated in type I and type II DM, has been shown to increase glomerular filtration rate in normal rats and to contribute to progression of chronic renal failure in 5͞6 nephrectomized rats. The present study was thus designed to evaluate whether VP contributes to the renal disorders of DM. Renal function was compared in Brattleboro rats with diabetes insipidus (DI) lacking VP and in normal Long-Evans (LE) rats, with or without streptozotocin-induced DM. Blood and urine were collected after 2 and 4 weeks of DM, and creatinine clearance, urinary glucose and albumin excretion, and kidney weight were measured. Plasma glucose increased 3-fold in DM rats of both strains, but glucose excretion was Ϸ40% lower in DI-DM than in LE-DM, suggesting less intense metabolic disorders. Creatinine clearance increased significantly in LE-DM (P < 0.01) but failed to increase in DI-DM. Urinary albumin excretion more than doubled in LE-DM but rose by only 34% in DI-DM rats (P < 0.05). Kidney hypertrophy was also less intense in DI-DM than in LE-DM (P < 0.001). These results suggest that VP plays a critical role in diabetic hyperfiltration and albuminuria induced by DM. This hormone thus seems to be an additional risk factor for diabetic nephropathy and, thus, a potential target for prevention and͞or therapeutic intervention.One of the major complications of diabetes mellitus (DM) is a progressive nephropathy that develops in about one-third of patients within 10-20 years after the onset of the disease and leads in most cases to end stage renal failure (1). This represents a major problem of public health because a large fraction of dialysis requirements is attributable to DM nephropathy. Although a number of studies have already been devoted to this problem, the factors contributing to diabetic nephropathy are not yet fully identified.A characteristic feature observed in diabetic patients is an elevation of plasma vasopressin (VP), well documented in both type I and type II DM (2-5). This elevation also occurs in animal models of DM, whether experimental or genetically determined (6, 7). Several studies have investigated the possible factors responsible for this increase in VP secretion (3,6,8,9). But they did not succeed in identifying the responsible stimulus for this increase. They revealed a resetting of the osmostat in diabetics but concluded that hyperglycemia was not responsible for this resetting because increasing plasma glucose and osmolality by intravenous infusion of hypertonic dextrose produced no increase in plasma vasopressin in diabetics or in healthy controls (8).Little attention has been given to the possible functional consequences of the rise in plasma VP. To our knowledge, the possible contribution of VP to the renal complications of DM has never been investigated in spite of several previous findings suggesting that this hormone represents a ...