Sympathetic nerves protect against stroke in stroke-prone hypertensive rats. A preliminary report

Studies were performed to determine whether sympathetic nerves protect against stroke in hypertensive rats. The superior cervical ganglion was removed on one side in 28 stroke-prone spontaneously hypertensive rats (SHRSP) when the rats were 4 weeks old. The rats were fed Japanese rat chow and 1% saline drinking water. When the rats were 19 weeks old, systolic pressure was 206 +/- 4 mm Hg (mean +/- SE). All rats died between 19 and 23 weeks of age. Microscopic and histological examination demonstrated cerebral hemorrhage in seven rats. All the hemorrhages occurred in the denervated hemispheres. Ischemic cerebral infarctions were found in 13 rats; in 10 rats, the infarcts were only in the denervated hemisphere. Pathological changes of cerebral arteries (hyalinosis, fibrinoid changes, and thrombus formation) were observed primarily in denervated hemispheres. Wall-to-lumen ratio was less in arteries of the denervated hemisphere than in arteries of the innervated hemisphere. These preliminary observations suggest that denervation of cerebral vessels increases susceptibility to stroke and inhibits development of cerebral vascular hypertrophy in SHRSP.