Structural, morphologic and morphometric study of the phrenic nerve: association between experimental diabetes and arterial hypertension (728.24)

Abstract

Although the association between hypertension and diabetes is common in clinical practice, it is not well known the contribution of each of these diseases in the development of diabetic neuropathy in patients with hypertension. We investigated the presence of peripheral neuropathy, through morphology and morphometry analysis of the phrenic nerve in normotensive rats (Wistar) and spontaneously hypertensive rats (SHR) with experimentally induced chronic diabetes. Diabetic animals received a single injection of streptozotocin (STZ) intravenously while controls received vehicle on the same date. Twelve weeks after injection, arterial pressure and heart rate were recorded and the right and left phrenic nerves were removed and prepared for embedding in epoxy resin and computer morphometry. The phrenic nerves of SHR and diabetic SHR (SHR + STZ) showed reduced number and density of myelinated fibers and Schwann cell nuclei, compared to Wistar. The SHR and SHR+STZ rats showed myelinated fiber size distributions skewed to the right, with an important reduction of the small myelinated fibers. This finding was more pronounced on diabetic SHR when compared to normotensive diabetic animals. We suggest that hypertension causes a reduction of small myelinated fibers and the association of the hypertension and diabetes did not interfere with the small fiber neuropathy present in the hypertensive animals.Grant Funding Source: CAPES, FAPESP, CNPq and FAEPA