Neuropathy in the spontaneously hypertensive rat: An electrophysiological and histological study

Abstract

SHR showed slowed nerve conduction velocity and pathological abnormalities of hindlimb nerves. Sustained severe hypertension may cause axonal atrophy and endoneurial microangiopathy. Muscle Nerve 54: 756-762, 2016.

Sensory and Motor Conduction Velocity in Spontaneously Hypertensive Rats: Sex and Aging Investigation

“…Despite our results of a continuous body weight increase in adult life in all animals studied (Figure 2), motor conduction velocity got stable at 20-week old hypertensive animals but continued to increase in normotensive ones (Figure 3), becoming statistically higher in 40 weeks old WKY compared to SHR. This is in agreement with previous nerve morphology results of thinning of the large myelinated fibers observed at 6 months of age (Tomassoni et al, 2004) and myelin splitting observed at 44 weeks of age (Nukada et al, 2016) in SHR with well-established hypertension. It is important to point out that the MCV values obtained in our normotensive rats are very similar to those reported for normotensive Wistar rats or WKY rats with similar ages investigated in the present study.…”

“…(0.1 ml/100 g of body weight) and subdermal needle electrodes (used both to stimulate and to record) were positioned as follows (Figure 1). Methods for measuring SCV and MCV were adapted from those previously described in the literature for rats (Baba et al, 1982, 2006; Nukada et al, 2016).…”

“…Previous reports suggested that hypertension could cause neuropathy in human beings (Chaco and Viskoper, 1971; Viskoper et al, 1971) but very little investigation on this issue was performed later. Laboratory animal models (Sabbatini et al, 1996; Fazan et al, 1999, 2001; Tomassoni et al, 2004; Fazan et al, 2005; Licursi de Alcântara et al, 2008; Rodrigues et al, 2011; Sanada et al, 2012; Nukada et al, 2016; da Silva et al, 2016) were investigated for the possibility of nerve fiber lesions in hypertension. For all these animal studies, the spontaneously hypertensive rats (SHR) were used for being considered a good model of human essential hypertension (Trippodo and Frohlich, 1981).…”

“…For all these animal studies, the spontaneously hypertensive rats (SHR) were used for being considered a good model of human essential hypertension (Trippodo and Frohlich, 1981). Also, despite a large number of rodent models of hypertension (Lerman et al, 2019), the SHR is still the most common rat model used for investigation of hypertensive target-organ damage and its treatment (Nukada et al, 2016; Lerman et al, 2019). Despite the morphological descriptions of a mild neuropathy, with mainly thin myelinated fibers alterations, in several functional distinct peripheral nerves (sensory, motor and autonomic), information on functional nerve alterations, particularly involving nerve conduction velocity in the SHR is still scarce.…”

Hypertension Contributes to Neuropathy in Patients With Type 1 Diabetes

“…8 In a hypertensive T2DM model, there was a reduction in sensory nerve conduction velocity and increased expression of matrix metalloproteinase at sites of myelin thinning 10 In nondiabetic hypertensive rats impaired epineurial arteriolar function was shown to contribute to reduced endoneurial perfusion and neuropathy 16 as well as axonal atrophy and myelin splitting with endoneurial microangiopathy. 17 However, treatment with fosinopril prevented the development and maintenance of tactile allodynia 18 and a combination of enalapril, α-lipoic acid and menhaden oil improved thermal hypoalgesia, intraepidermal nerve fiber profiles, and corneal subbasal nerve fiber length in a normotensive T2DM model. 19 These improvements were related to improved vascular relaxation to acetylcholine and calcitonin gene-related peptide in sciatic nerve epineurial arterioles.…”