Structural and functional consequence of neonatal sympathectomy on the blood vessels of spontaneously hypertensive rats.

Abstract

SUMMARY Neonatal sympathectomy of spontaneously hypertensive rats (SHR) and control Wistar-Kyoto rats (WKY) was performed by a combined treatment with antiserum to nerve growth factor and guanethidine during the first 4 weeks after birth. The development of hypertension was completely prevented in the treated SHR: at 28 to 30 weeks of age, systolic blood pressure of treated SHR was 139 ± 2 mm Hg as compared with 195 ± 8 mm Hg in untreated SHR. The extent of sympathectomy was verified by histofluorescence. Fluorescence histochemistry for catecholamine-containing nerves showed a complete absence of adrenergic nerves in the mesenteric arteries of treated rats. A supersensitivity to norepinephrine was exhibited by mesenteric arteries, anococcygeus muscle, and tail arteries from the treated SHR and WKY. In the mesenteric vascular bed, maximal response to norepinephrine was significantly reduced by sympathectomy. Sympathectomy also abolished the responses (e.g., generation of excitatory junctional potentials) of tail arteries to electrical stimulation of perivascular nerves. Morphometric measurements of three categories of mesenteric arteries showed that sympathectomy had no effect on the hypertrophic change of smooth muscle cells in the conducting vessels, but it prevented the hyperplastic changes of the muscle cells from reactive, muscular arteries and small resistance vessels. These results suggest that one of the primary roles of the overactive sympathetic nervous system in the development of hypertension in SHR is manifested through its trophic effect on the arteries of SHR. This trophic effect appears to cause a hyperplastic change in the smooth muscle cells in the reactive and resistance vessels, thereby contributing to the development of hypertension in older SHR. (Hypertension 10: 328-338, 1987) KEY WORDS • sympathetic nervous system • hypertension • arteries • spontaneously hypertensive rats • nerve growth factor • guanethidine

Noninvasive Evaluation of the Time Course of Change in Cardiac Function in Spontaneously Hypertensive Rats by Echocardiography

“…An early increase of LV weight was also observed in SHR of the present study, and previous reports have demonstrated that sympathetic nerve stimulation might play an important role in early stage LV hypertrophy (14,15). Furthermore, Dang et al (16) showed that LV tissue angiotensin-II concentrations were significantly higher in SHR than in WKY from 15 to 28 weeks of age, although plasma angiotensin-II levels were similar in both groups.…”

Peptide-containing nerves around blood vessels of stroke-prone spontaneously hypertensive rats.

“…A sensory function has been suggested for SP in the vascular nerves, 1 yet, neonatal treatment of spontaneously hypertensive rats (SHR) with capsaicin, which presumably depletes neuronal SP, also prevented hypertension development in these rats, 2 suggesting SP may have other functions besides a sensory function. In our recent study on the effect of sympathectomy on hypertension development and vessel wall morphology, 3 we found that despite the destruction of sympathetic nerves with our procedure, other nerve types were still present.The primary aim in our present study was to locate and identify various peptide-containing nerves from the cerebral and peripheral blood vessels of stroke-prone SHR (SHRSP) and Wistar-Kyoto rats (WKY). Our intent was to relate the distribution of these nerves to the known action of the peptides so that we could gain some understanding concerning the possible involvement of these nerves in the development of hypertension.…”

“…A sensory function has been suggested for SP in the vascular nerves, 1 yet, neonatal treatment of spontaneously hypertensive rats (SHR) with capsaicin, which presumably depletes neuronal SP, also prevented hypertension development in these rats, 2 suggesting SP may have other functions besides a sensory function. In our recent study on the effect of sympathectomy on hypertension development and vessel wall morphology, 3 we found that despite the destruction of sympathetic nerves with our procedure, other nerve types were still present.…”

“…8 In SHR, the parental stock of SHRSP, adrenergic innervation of large and small mesenteric arteries was denser than in WKY. 3 Therefore, it is not surprising that NPY nerves in SHRSP were also found to be denser than in WKY. The NPY nerve density in the veins was also higher in SHRSP than in WKY.…”

“…This is consistent with our previous observation that sympathetic nerves in the cerebral arteries of SHR were not affected by our procedure. 3 It is possible that our procedure is not effective against nerves that are already established, because at birth, the cerebral arteries of SHR are already innervated, whereas innervation in the mesenteric arteries occurs after birth (E.I. Mangiarua and R.M.K.W.…”