New establishment of hypertensive diabetic animal models: neonatally streptozotocin-treated spontaneously hypertensive rats.

Hypertensive diabetic animal models have been developed by injecting streptozotocin (STZ) in neonatal stroke-resistant spontaneously hypertensive rats (SHRSR) and stroke-prone SHR (SHRSP) at the age of two days. After the treatment, the animals showed mild insulin deficiency and mild hyperglycemia at the age of three to four months. Diabetic nephropathy was produced particularly in STZ-treated SHRSR at the age of six months. The effect of neonatal STZ injection on hyperglycemia varied among normotensive Wistar-Kyoto rats (WKY), SHRSR, and SHRSP; SHRSR showed the highest glucose levels, SHRSP showed intermediate levels, and WKY was the lowest. All STZ-treated SHRSR showed glycosuria, while glycosuria was not observed in the treated SHRSP and WKY. Histologic study indicated that these strain differences were partly ascribed to differences in islet B-cell sensitivity to toxic effects of STZ. The development of hypertension was not accelerated in these SHRSR and SHRSP compared with respective nontreated controls. Since STZ-treated SHRSR develop mild diabetic symptom with hypertension and develop mild diabetic glomerulosclerosis, they are good models for studying vascular complications or other problems relating to the synergism between hypertension and diabetes mellitus.