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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the present study we examined whether the angiotensin I converting enzyme inhibitor, captopril, would protect stroke-prone spontaneously hypertensive rats (SHRSP) from stroke and renal pathology over a 26-week period. In the control group of six untreated SHRSP fed Stroke-Prone Rodent Diet and 1% NaCl drinking solution, all animals developed severe hypertension and stroke by 16.1 weeks of age. In eight salt-loaded SHRSP treated with oral captopril (50 mg/kg/day) beginning at 8.4 weeks of age, systolic blood pressure was slightly but temporarily suppressed and then continued to rise; by 12 weeks of age systolic blood pressure reached levels of severe hypertension, 240 +/- 8 mm Hg, and did not differ from that of untreated SHRSP. No deaths or brain lesions were noted in captopril-treated SHRSP despite severe hypertension maintained through 26 weeks of age when the study ended. Captopril treatment prevented increases in urinary protein excretion (14 +/- 2 v 63 +/- 16 mg/day at 11.7 weeks of age, P less than .01) and the severe brain, renal, and cardiac vascular lesions observed in untreated SHRSP. When maintained on Stroke-Prone Rodent Diet and saline, plasma renin activity of untreated SHRSP surviving until 14.5 weeks of age was markedly increased (29.1 +/- 9.4 ng Ang I/mL/h) compared with either untreated SHRSP (9.2 +/- 2.5 ng Ang I/mL/h, P less than .01) or Wistar-Kyoto rats (3.5 +/- 1.0 ng Ang I/mL/h, P less than .01) maintained on standard diet and water.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Therapeutic benefit of captopril in salt-loaded stroke-prone spontaneously hypertensive rats is independent of hypotensive effect. 193 Aug 50

Stroke-Prone spontaneously hypertensive rat strain (SHR-SP) always develops hypertensive retinopathy. The aim of the present work was to study the activity of a new antihypertensive drug, a synthetic furopyridine: cicletanine, in retinal hypertensive morphological lesions. The experiment was performed in 39 rats SHR-SP/A3N Iffa Credo, 11 weeks old, divided into 3 groups: group 1 was the control group, groups 2 and 3 were orally treated with cicletanine (respectively 100 and 150 mg/kg). All the rats had free access to tap water containing 1 p. 100 NaCl. During 6 weeks, blood pressure, body weight and survival were recorded, then all the rats were sacrificed. The eyes were removed, the posterior pole collected and fixed with Trump liquid for transmission election microscopy. In the SHR-SP control group, each layer showed neural body and/or process lesions: in the ganglion cell layer, some ganglion cells realized cytoid bodies corresponding to a lysed cell with nucleus degeneration, most of the axons were destroyed. In the inner and outer plexiform layers, most of the contacts between processes were lost because of fibrinous deposits. Numerous synapses were destroyed in the outer plexiform layer. These findings might explain the numerous dense bodies in the inner rod segment and the vesiculation of the rod outer segment. The capillaries showed markedly hypertensive lesions. Whereas, in both treated groups, rare and animal lesions were observed. The fact that these lesions were so few and so unimportant after 6 weeks of treatment, as well as for the photoreceptors which remained unimpaired, is closely related to cicletanine therapy, since it was so even though the treatment had been started with an already high blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Malignant hypertensive retinopathy in spontaneously hypertensive stroke-prone rats. Effect of treatment with cicletanine]. 251 Jun 62

In the caudal and renal arteries of the male Wistar rat, interruptions in the internal elastic lamina (IEL) form spontaneously with age. beta-aminopropionitrile (BAPN), which is an inhibitor of the enzyme lysyl oxidase implicated in the synthesis of elastin, is able to induce in the young Wistar rat interruptions in the IEL which are morphologically very similar to those which form spontaneously. The spontaneously hypertensive strain (SHR), together with the Stroke-Prone spontaneously hypertensive substrain (SHR-SP) which is susceptible to cerebrovascular accidents early in life, have been selected from the Wistar strain. We have compared the incidence of IEL interruptions in caudal and renal arteries from SHR-SP aged 12 and 23 weeks with that observed in age-matched SHR. In addition, we have studied the effect of BAPN, administered from weaning during two weeks, on the formation of interruptions in the IEL in the caudal artery of SHR-SP, SHR and normotensive Wistar and WKY rats. Interruptions in the IEL were quantified by light microscopy on longitudinal semi-thin sections. Results showed that, in the caudal and renal arteries of SHR-SP, the number of interruptions in the IEL which form spontaneously was greater than in SHR. Moreover, BAPN administered between the age of 3 and 5 weeks led to the premature formation of a higher level of interruptions in the IEL in SHR-SP than in the 3 other strains of rat. The SHR was the strain which developed the least.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Formation of disruptions of the internal elastica lamina, spontaneous and BAPN induced, in arteries of stroke-prone spontaneously hypertensive rats]. 311 72

To develop a system to be used for confirming diagnosis of Tyzzer's disease in seropositive rat colonies, 38 Mol:SPRD, BB/Wor/Mol-BB, and Stroke-Prone rats suffering from megaloileitis were examined. All affected rats had been found by a systematic examination of 5-week-old male rats from barrier-protected colonies, sero-positive to Bacillus piliformis, the agent of Tyzzer's disease. The rats were evaluated by serologic testing, histologic examination of the ileum, liver, and heart (hematoxylin and eosin and Warthin-Starry staining), and immunofluorescence staining of tissue smears of the ileum and liver. The presence of B. piliformis was verified in 24 of the rats. All animals that had the agent in the liver or heart also had it in the ileum. The sensitivity of immunofluorescence staining for identification of the agent was higher than that for Warthin-Starry staining. Thirty-seven rats had histologic changes indicative of Tyzzer's disease in the liver, and 23 had histologic changes in the myocardium. All rats had a high titer of antibodies against B. piliformis. Having verified the presence of the agent, germ-free sentinels were placed in one of the colonies. These also became infected, as did germ-free sentinels caged with the infected rats outside the barrier unit. The number of sentinels infected increased with the age of the sentinels at introduction. To prove the absence of Tyzzer's disease in a seropositive colony, it is considered necessary to examine approximately 3,000 5-week-old rats for abdominal distension and demonstrate negative staining of the ileum for B. piliformis.
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PMID:Studies on the diagnosis of Tyzzer's disease in laboratory rat colonies with antibodies against Bacillus piliformis (Clostridium piliforme). 753 Dec 55

Many reports indicate that GM1 ganglioside is effective in reducing CNS ischemic injury in animal models. These models employ invasive surgery to induce ischemic damage in otherwise healthy animals. The purpose of this study was to determine if the beneficial effects of GM1 could be generalized to Spontaneously Hypertensive Rats-Stroke Prone (SHRSP). The SHRSP strain develops a pathology similar to those observed in patients with stroke. The SHRSP have "risk" factors that include hypertension, fibrinoid necrosis, and sensitivity to diet. Female SHRSP were randomly assigned to GM1- or saline-treatment conditions. Rats were fed a stroke-inducing diet. Daily body weights, weekly blood pressure, time of stroke onset, and age at death were recorded. Spontaneous activity and performance on a tail-hang test were assessed thrice weekly. The results indicate that GM1 treatment did not delay the time of stroke onset or death. GM1 did reduce hyperactivity in the initial stages of the ischemic pathology, but did not prevent the marked decline in behavioral activity observed at later time points. There were no differences in weight loss, performance on the tail-hang test, or number of CNS injury-related symptoms observed. These findings suggest that GM1 was not as effective in decreasing mortality, weight loss, or behavioral deficits in SHRSP as previously reported using other animal models of ischemia. Distinguishing between those animal models in which GM1 is more and less effective may be useful in determining under which clinical situations GM1 is likely to be most suitable.
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PMID:GM1 ganglioside treatment of spontaneously hypertensive stroke prone rats. 815 30

Experiments were performed to determine the effect of chronic therapy with the potent and long-acting thromboxane (TX) A2/prostaglandin endoperoxide (TP) receptor antagonist, ifetroban, on hypertension development and the incidence of stroke in stroke-prone spontaneously hypertensive rats (SHRSP). SHRSP instrumented with radiotelemetry probes, for continuous monitoring of arterial blood pressure, were given 1% NaCl to drink and Stroke-Prone Rodent Diet and were chronically treated with ifetroban (20 mg/kg/day, n = 10) or vehicle (n = 12) starting at 16.5 weeks of age. Ifetroban did not affect blood pressure or the development of proteinuria and cerebrovascular lesions. Chronic administration of a higher dose ifetroban (40 mg/kg/day) starting at 7 weeks of age was also without effect on blood pressure and stroke in noninstrumented saline-drinking SHRSP. These results do not support a major role for TXA2 and its endoperoxide precursors in the elevation of blood pressure and the development of cerebrovascular lesions in saline-drinking SHRSP.
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PMID:Effect of ifetroban, a thromboxane A2 receptor antagonist, in stroke-prone spontaneously hypertensive rats. 886 99

Enormous differences exist between rat strains with respect to the infarct volume induced by unilateral middle cerebral artery (MCA) occlusion. We performed three experiments to address the following questions. Firstly, whether the pattern of MCA-occlusion (MCA-O) induced sensorimotor impairments in rats are strain dependent; secondly, whether proximal (i.e., close to its origin) and distal occlusions (above the lenticulostriate branch) of the MCA affect infarct volume and the behavioral impairments to a different extent; and thirdly, whether there is a relationship between the infarct volume and behavioral deficits. We found that the pattern of sensorimotor malfunctions induced by proximal unilateral MCA-O were highly strain dependent. Of the eight strains tested, Winkelmann-Wistar rats, Spontaneously Hypertensive Stroke-Prone rats, and Wistar-Kyoto rats were most severely affected. By contrast, Brown-Norway rats showed only mild behavioral deficits after the MCA-O. The second experiment confirmed that proximal occlusions induced slightly more behavioral malfunctions than distal occlusions did. Histological evaluation of the brain damage caused by proximal and distal MCA-O, confirmed that distal MCA-O damaged nearly exclusively cortical areas, and spared the caudate/putamen. An exploratory analysis of the relationship between infarct volume and behavioral deficits did not indicate that the severity of sensorimotor malfunctions can be predicted from the size of the infarct.
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PMID:Sensorimotor impairments in rats with cerebral infarction, induced by unilateral occlusion of the left middle cerebral artery: strain differences and effects of the occlusion site. 891 66

Stroke-prone spontaneously hypertensive rats (SHRSP) on 1% NaCl drinking solution and Stroke-Prone Rodent Diet develop severe hypertension and glomerular and vascular lesions characteristic of thrombotic microangiopathy seen in malignant nephrosclerosis. We recently reported that spironolactone, a mineralocorticoid receptor antagonist, markedly reduced proteinuria and malignant nephrosclerotic lesions in these animals. This observation, together with our previous findings that angiotensin-converting enzyme inhibitors prevent the development of vascular damage, suggests that mineralocorticoids, as part of the renin-angiotensin-aldosterone system, play a pathophysiological role in this model. In the present study, we examined whether chronic (2-week) infusion of aldosterone can reverse the renal vascular protective effects of captopril in SHRSP. SHRSP received vehicle (n=8); captopril alone (50 mg. kg-1. d-1, orally) (n=10); aldosterone infusion alone (40 microg. kg-1. d-1, SC) (n=7); or captopril and aldosterone at 20 (n=6) or 40 (n=7) microg. kg-1. d-1. Systolic blood pressure was markedly elevated in all groups. Vehicle- and aldosterone-infused SHRSP developed severe proteinuria and comparable degrees of renal injury (21+/-3% and 29+/-3%, respectively) manifested as thrombotic and proliferative lesions in the arterioles and glomeruli. Captopril treatment reduced plasma aldosterone levels concomitant with marked reductions in proteinuria and the absence of histologic lesions of malignant nephrosclerosis. Aldosterone substitution at 20 or 40 microg. kg-1. d-1 in captopril-treated SHRSP resulted in the development of severe renal lesions (16+/-3% and 21+/-2%, respectively) and proteinuria comparable with that observed in SHRSP given either aldosterone or vehicle alone. These findings support a major role for aldosterone in the development of malignant nephrosclerosis in saline-drinking SHRSP, independent of the effects of blood pressure.
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PMID:Role of aldosterone in renal vascular injury in stroke-prone hypertensive rats. 993 Nov 10

Ischemic preconditioning (PC) is a phenomenon whereby a brief exposure to ischemia renders a tissue more tolerant to a subsequent sustained ischemic insult. Animals of the Spontaneously Hypertensive (SHR) and the Spontaneously Hypertensive Stroke-Prone (SHR-SP) rat strains produce cerebral infarcts that are larger and more reproducible in size than infarcts of normotensive rats. This study compared the effects of PC in SHR and SHR-SP rats, under the hypothesis that PC may not be as effective in the SHR-SP, a strain genetically predisposed to stroke. There were two groups per strain, with between eight and ten animals each. The Precondition group (PC) had a 10 min occlusion of the middle cerebral artery on day -1. On the same day the Sham group (Sham) received sham surgery. On day 0, both groups underwent permanent occlusion of the middle cerebral artery. The ischemic lesion was measured on day 1 using T(2)-weighted magnetic resonance imaging. Percent hemispheric infarct was significantly reduced in SHR PC vs. SHR Sham, SHR-SP PC vs. SHR-SP Sham, and SHR PC vs. SHR-SP PC. Thus, rats of the SHR-SP strain respond to PC less markedly than SHR animals. Both models may now be used to elucidate the mechanisms underlying PC.
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PMID:Strain-dependent response to cerebral ischemic preconditioning: differences between spontaneously hypertensive and stroke prone spontaneously hypertensive rats. 1261 17

Estrogen produces both beneficial and adverse effects on cardiovascular health via mechanisms that remain unclear. Stroke-prone spontaneously hypertensive rats (SHRSP) maintained on Stroke-Prone Rodent Diet and 1% NaCl drinking water (starting at 8 wk of age) rapidly develop stroke and malignant nephrosclerosis that can be prevented, despite continued hypertension, by drugs targeting angiotensin II and aldosterone actions. This study evaluated estrogen's effects in the SHRSP model. Female SHRSP that were sham operated (SHAM), ovariectomized (OVX) at 4 wk of age, or OVX and treated with estradiol benzoate (E2,30 microg x kg-1 x wk-1) were studied. In a survival protocol, OVX rats lived significantly longer (15.1 +/- 0.3 wk) compared with SHAM (13.6 +/- 0.2 wk) or OVX+E2 rats (12.4 +/- 0.2 wk). In a protocol in which animals were matched for age, at 11.5 wk, terminal systolic blood pressure and urine protein excretion were elevated in SHAM and OVX+E2 rats compared with OVX rats; blood urea nitrogen, renal microvascular and glomerular lesions, and plasma renin concentration were elevated in OVX+E2 relative to SHAM or OVX rats. In a survival protocol using intact female SHRSP, treatment with an antiestrogen (tamoxifen, 7 mg.kg-1.wk-1) prolonged survival by >2 wk compared with controls (P < 0.01). The data indicate that estrogen promotes microangiopathy in the kidney and stroke in saline-drinking SHRSP.
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PMID:Estrogen promotes microvascular pathology in female stroke-prone spontaneously hypertensive rats. 1267 Aug 33


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