THE EFFECTS OF HYPERTENSION ON CEREBRAL ATHEROSCLEROSIS IN THE CYNOMOLGUS MONKEY

Background and Purpose: There is substantial clinical, pathological, and experimental evidence that hypertension aggravates atherosclerosis of the extracranial vessels. The present study assesses the effects of hypertension on the development of cerebral atherosclerosis in nonhuman primates fed an atherogenic diet. Methods: The extent and severity of cerebral atherosclerosis were evaluated morphologically, morphometrically, and biochemically in atherosclerotic monkeys with and without hypertension. Atherosclerosis was induced by feeding a hypercholesterolemic diet for 12 months; hypertension was produced by surgical coarctation of the thoracic aorta. Results: At autopsy, gross atherosclerotic lesions of the major cerebral arteries were observed in 15 of 16 atherosclerotic monkeys with hypertension compared with 5 of 16 atherosclerotic animals without hypertension. In the hypertensive-atherosclerotic group, 38.5% of the vessels examined showed gross involvement compared with only 3.4% of the vessels involved in the atherosclerotic group (P<.001). The lesions in the atherosclerotic group were generally mild, whereas those in the hypertensive-atherosclerotic group were severe and resulted in significant luminal narrowing and occlusion of vessels (P<.001). The small branches of the cerebral arteries also showed severe disease with luminal obstruction in the hypertensive-atherosclerotic group. The extent and severity of cerebral atherosclerosis were significantly related to the severity of the hypertension (P<.05). Conclusions: Hypertension is an important factor in cerebral atherosclerosis because of its accelerating effect on the disease. Nonhuman primate models may be useful in clarifying the role of hypertension and atherosclerosis in cerebral vascular disease.