Morphological and conduction changes in the sciatic nerve of spontaneously hypertensive rats

The morphology and function of sciatic nerve were investigated in spontaneously hypertensive rats (SHR), either control or hydralazine-treated, and in normotensive Wistar Kyoto rats of 6 months of age. In control SHR decreased percentages of class I fibers (20-15 microm in diameter), of axonal NFP-H 200 kDa neurofilament protein immunoreactivity and of nerve conduction velocity were found. The percentages of class III (10-5 microm in diameter) and IV (<5 microm in diameter) and of S100beta-immunoreactive Schwann cell profiles were increased. Treatment with the hypotensive drug hydralazine countered sciatic nerve changes. The shift of nerve composition vs. smaller fibers is probably the cause of reduced nerve conduction velocity found in SHR and is consistent with the occurrence of a sympathetic hyper innervation in this animal model of hypertension. Our findings support the hypothesis that arterial hypertension may represent a risk factor of neuropathy.