Normotensive Wistar Rats Research Articles

A Subpressor Dose of Angiotensin II Elevates Blood Pressure in a Normotensive Rat Model by Oxidative Stress

Oxidative stress is an imbalance between free radicals and antioxidants, and is an important etiological factor in the development of hypertension. Recent experimental evidence suggests that subpressor doses of angiotensin II elevate oxidative stress and blood pressure. We aimed to investigate the oxidative stress related mechanism by which a subpressor dose of angiotensin II induces hypertension in a normotensive rat model. Normotensive male Wistar rats were infused with a subpressor dose of angiotensin II for 28 days. The control group was sham operated and infused with saline only. Plasma angiotensin II and H2O2 levels, whole-blood glutathione peroxidase, and AT-1a, Cu/Zn SOD, and p22phox mRNA expression in the aorta was assessed. Systolic and diastolic blood pressures were elevated in the experimental group. There was no change in angiotensin II levels, but a significant increase in AT-1a mRNA expression was found in the experimental group. mRNA expression of p22phox was increased significantly and Cu/Zn SOD decreased significantly in the experimental group. There was no significant change to the H2O2 and GPx levels. Angiotensin II manipulates the free radical-antioxidant balance in the vasculature by selectively increasing O2(-) production and decreasing SOD activity and causes an oxidative stress induced elevation in blood pressure in the Wistar rat.

Hypertension exacerbates predisposition to neurodegeneration and memory impairment in the presence of a neuroinflammatory stimulus: Protection by angiotensin converting enzyme inhibition

Hypertension is a risk factor for cognitive impairment. Furthermore, neuroinflammation and neurodegeneration are intricately associated with memory impairment. Therefore, the present study aimed to explore the involvement of hypertension and angiotensin system in neurodegeneration and memory dysfunction in the presence of neuroinflammatory stimulus. Memory impairment was induced by chronic neuroinflammation that was developed by repeated intracerebroventricular (ICV) injections of lipopolysaccharide (LPS) on the 1st, 4th, 7th, and 10th day. Memory functions were evaluated by the Morris water maze (MWM) test on days 13–15, followed by biochemical and molecular studies in the cortex and hippocampus regions of rat brain. LPS at the dose of 25μg ICV caused memory impairment in spontaneously hypertensive rats (SHRs) but not in normotensive Wistar rats (NWRs). Memory deficit was obtained with 50μg of LPS (ICV) in NWRs. Control SHRs already exhibited increased angiotensin converting enzyme (ACE) activity and expression, neuroinflammation (increased TNF-α, GFAP, COX-2 and NF-kB), oxidative stress (increased iNOS, ROS and nitrite levels), TLR-4 expression and TUNEL positive cells as compared to control NWRs. Further, LPS (25μg ICV) exaggerated inflammatory response, oxidative stress and apoptosis in SHRs but similar effects were witnessed at 50μg of LPS (ICV) in NWRs. Oral administration of perindopril (ACE inhibitor), at non-antihypertensive dose (0.1mg/kg), for 15days attenuated LPS induced deleterious changes in both NWRs and SHRs. Our data suggest that susceptibility of the brain for neurodegeneration and memory impairment induced by neuroinflammation is enhanced in hypertension, and that can be protected by ACE inhibition.

Renal Functional Responses to Angiotensin 1‐7 (Ang1‐7) in the Spontaneously Hypertensive Rat (SHR)

There is evidence that the natriuretic and diuretic actions of Ang1‐7 are dependent on the degree of activation of the renin angiotensin system but it is uncertain whether they are independent of blood pressure. This study examined the effect of intra‐renal infusion of Ang1‐7 on sodium and water excretion in SHR and normotensive Wistar rats, in which both strain's plasma renin and angiotensin II are similar. Twelve week old male Wistar or SHRs (n=7) were anaesthetised and prepared for measurement of mean arterial pressure (MAP), glomerular filtration rate (GFR), urine flow (UV) and fractional sodium excretion (FENa). Clearances, of 20 min, were taken before and during the intra‐renal infusion of saline or Ang1‐7 (3x10‐3M) at 1ml/h. Means±SEM were compared (Wilcoxon matched pairs) and significance taken at P<0.05. Intra‐renal Ang1‐7 infusion did not change MAP or GFR in either SHR or Wistar groups, at 172±9 and 113±6mmHg and 3.4±0.3 and 4.8±0.2ml/min/kg respectively. UV and FENa increased from 57.5±11.1 to 69.3±9.1µl/min/kg and 1.6±0.3 to 2.5±0.3% (P<0.05) in the SHR group and from 96.0±3.9 to 132.1±8.1µl/min/kg and from 1.8±0.1 to 2.3±0.1% (P<0.05) in the Wistar group. These responses were not significantly different across the groups. These findings showed that Ang1‐7 infusion into the kidney caused a diuresis and natriuresis, the magnitude of which was indistinguishable between SHR and normotensive Wistar rats. They indicate that the elevated MAP in the SHR does not contribute to the magnitude of the excretory responses. The data further support the view that the natriuretic and diuretic actions of Ang1‐7 are dependent on the status of the endogenous renin‐angiotensin system but are independent of blood pressure.

Reduced Dilatory Capacityof Brainstem Parenchymal Arteries of Young Spontaneously Hypertensive Rats

Our recent data suggest that spontaneously hypertensive rats (SHR) show reduced functional hyperemia and impaired relaxation of vertebral and basilar arteries. Here, using brainstem slices from pre‐hypertensive SHR (PHSHR, P21‐P30), young hypertensive SHR (YHSHR, P45‐P70) and age‐matched normotensive Wistar rats, we compared vascular dilatory capacity of both pial and penetrating parenchymal arterioles. Changes in vascular diameter in response to application of vasodilator agents, adenosine (1‐10 µM) and sodium nitroprusside (1‐10 µM), were assessed after pre‐constriction with a thromboxane agonist (U46619 70 nM). In PHSHR and aged‐matched Wistar rats, treatment with U46619 constricted parenchymal arterioles to 82±7% and 88±2% of their resting diameters: 15±3μm and 16±2μm, respectively. These responses remained unchanged in YHSHR and their aged‐matched controls. Adenosine reversed the U46619‐induced vasoconstriction by 24% and 30% in PHSHR and Wistar controls, respectively. In contrast, adenosine failed to reduce vasoconstriction in YHSHR, although its vasodilator efficiency in aged‐matched Wistar rats remained unaltered. Likewise, superfusion with sodium nitroprusside reduced the U46619‐induced vasoconstriction in penetrating arterioles from PHSHR, but not YHSHR. Intriguingly, vasodilator efficiency of adenosine in pial arterioles of a similar size (21±4 μm) was preserved in YHSHR. These results suggest that the dilatory capacity of brainstem parenchymal arteries is reduced in YHSHR. Whether this contributes to neurogenic hypertension remains to be determined. The distinct responses of parenchymal versus pial arterioles in YHSHR suggest that the impaired dilatory reserve cannot be ascribed to increased blood pressure per se. BHF funded research.

English

This work investigated the effects of the ethanolic extract (EEJg) of aerial parts of Jatropha gossypiifolia L. and its aqueous (AFJg) and chloroformic (CFJg) fractions on the blood pressure and vascular reactivity (VR) in normotensive Wistar rats (NWR) and spontaneously hypertensive rats (SHR). In anaesthetized NWR, the EEJg and its fractions reduced mean blood pressure (MAP). The oral administration of EEJg (100 mg/kg/bw), for 8 weeks, did not alter MAP and heart rate in the non-anesthetized SHR. VR was determined in mesenteric artery rings, with the EEJg and fractions inhibiting the contractile responses to noradrenaline (NA, 10-9 to 10-4 M) in NWR, but not in SHR. In addition, the CFJg inhibited the contractile response to calcium (CaCl2, 10-6 to 10-2 M). These results suggest that J. gossypiifolia L. has no effect on the hypertensive factors in SHR, which is a model of polygenic hypertension, but indicate the presence of substances with hypotensive activity, which act directly on the adrenoceptor and/or decrease calcium mobilization in NWR. Key words: Jatropha gossypiifolia L., vascular reactivity, hypertension, calcium, mesenteric artery.

Brainstem hypoxia contributes to the development of hypertension in the spontaneously hypertensive rat.

Systemic arterial hypertension has been previously suggested to develop as a compensatory condition when central nervous perfusion/oxygenation is compromised. Principal sympathoexcitatory C1 neurons of the rostral ventrolateral medulla oblongata (whose activation increases sympathetic drive and the arterial blood pressure) are highly sensitive to hypoxia, but the mechanisms of this O2 sensitivity remain unknown. Here, we investigated potential mechanisms linking brainstem hypoxia and high systemic arterial blood pressure in the spontaneously hypertensive rat. Brainstem parenchymal PO2 in the spontaneously hypertensive rat was found to be ≈15 mm Hg lower than in the normotensive Wistar rat at the same level of arterial oxygenation and systemic arterial blood pressure. Hypoxia-induced activation of rostral ventrolateral medulla oblongata neurons was suppressed in the presence of either an ATP receptor antagonist MRS2179 or a glycogenolysis inhibitor 1,4-dideoxy-1,4-imino-d-arabinitol, suggesting that sensitivity of these neurons to low PO2 is mediated by actions of extracellular ATP and lactate. Brainstem hypoxia triggers release of lactate and ATP which produce excitation of C1 neurons in vitro and increases sympathetic nerve activity and arterial blood pressure in vivo. Facilitated breakdown of extracellular ATP in the rostral ventrolateral medulla oblongata by virally-driven overexpression of a potent ectonucleotidase transmembrane prostatic acid phosphatase results in a significant reduction in the arterial blood pressure in the spontaneously hypertensive rats (but not in normotensive animals). These results suggest that in the spontaneously hypertensive rat, lower PO2 of brainstem parenchyma may be associated with higher levels of ambient ATP and l-lactate within the presympathetic circuits, leading to increased central sympathetic drive and concomitant sustained increases in systemic arterial blood pressure.

Spontaneously hypertensive rats have more orexin neurons in their medial hypothalamus than normotensive rats.

What is the central question of this study? Blockade of orexin receptors reduces blood pressure in spontaneously hypertensive rats (SHRs) but not in normotensive Wistar-Kyoto (WKY) rats, suggesting that upregulation of orexin signalling underlies the hypertensive phenotype of the SHR. However, it is not known what causes this upregulation. What is the main finding and its importance? Using orexin immunolabelling, we show that SHRs have 20% more orexin neurons than normotensive WKY and Wistar rats in the medial hypothalamus, which is a good match to their blood pressure phenotype. In contrast, there is no such match for the orexin neurons of the lateral hypothalamus. Essential hypertension may be linked to an increase in orexin neurons in the medial hypothalamus. The neuropeptide orexin contributes to the regulation of blood pressure as part of its role in the control of arousal during wakefulness and motivated behaviour (including responses to psychological stress). Recent work shows that pharmacological blockade of orexin receptors reduces blood pressure in spontaneously hypertensive rats (SHRs) but not in normotensive Wistar-Kyoto (WKY) rats. It is not clear why orexin signalling is upregulated in the SHR, but one possibility is that these animals have more orexin neurons than their normotensive WKY and Wistar relatives. To test this possibility, SHRs, WKY and Wistar male rats (6-16 weeks old) were killed, perfused and their brains sectioned and immunolabelled for orexin A. Labelled neurons were plotted and counted in the six best labelled hemisections (120 μm apart) of each brain. There were significantly more orexin neurons (+20%) in the medial hypothalamus (medial to fornix) of SHRs compared with WKY and Wistar rats (126 ± 4 versus 106 ± 5 and 104 ± 5 per hemisection, respectively, P < 0.05), which matches well the blood pressure phenotypes. In contrast, counts in the lateral hypothalamus did not match the blood pressure phenotypes (69 ± 2 versus 50 ± 3 and 76 ± 4, respectively). The results support the idea that orexin signalling is upregulated in the SHR and suggest that this is due, at least in part, to a greater number of orexin neurons in the medial hypothalamus. These medial orexin neurons, which are also involved in hyperarousal and stress responses, may contribute to the development of essential hypertension.

Association of chronic diabetes and hypertension in sural nerve morphometry: an experimental study.

BackgroundProspective studies have shown incidence rates of hypertension in diabetes mellitus to be three times that of subjects without diabetes mellitus. The reverse also applies, with the incidence of diabetes two to three times higher in patients with hypertension. Despite this common clinical association, the contribution of each isolated entity in the development of a neuropathy is still not well understood. The aims of the present study were to investigate the presence of peripheral neuropathy in spontaneously hypertensive rats (SHR) and SHR with chronically induced diabetes, using a morphological and morphometric study of the sural nerves.MethodsFemale SHR and normotensive Wistar rats (WR), 8 weeks old, received a single intravenous injection of streptozotocin (STZ) through the tail vein. Controls from both strains received vehicle. Twelve weeks after the injection, sural nerves were dissected and prepared for light microscopy. Morphometry of sural nerve fascicles and myelinated fibers was performed with the aid of computer software.ResultsThe sural nerve myelinated fibers were highly affected by experimental diabetes in normotensive rats, causing mainly the reduction of the fiber size. Hypertensive rats showed characteristics of small fiber neuropathy and a severe reduction of the number and density or Schwann cells. The association between diabetes and hypertension caused an increase on the average size of the myelinated fibers, pointing to a small fiber loss, associated to axonal atrophy.ConclusionsOur study gives morphological support to the existence of a neuropathy due to hypertension, which is among one of the most common risk factors for diabetic neuropathy. The association between the two neuropathies showed to be a complex alteration, involving and including both, large and small fibers neuropathy. Hypertension caused, indeed, an exacerbation of the alterations already observed in experimental models of diabetic neuropathy.

Protective effect of telmisartan on neurovascular unit and inflammasome in stroke-resistant spontaneously hypertensive rats

Objectives:Hypertension is a crucial risk factor for both stroke and dementia, including Alzheimer’s disease (AD). We inspected the effect of telmisartan on the neurovascular unit (NVU) and related inflammatory responses in spontaneously hypertensive rat stroke resistant (SHR-SR) by observing the components of NVU such as N-acetyl glucosamine oligomer (NAGO), collagen IV, astrocytes, and matrix metalloproteinase-9 (MMP-9), as well as inflammasome NOD-like receptors family protein 3 (NLRP3).Methods:In the present study, we examined the effect of a highly selective angiotensin type 1 (AT-1) antagonist of angiotensin 2 receptor with high lipid solubility, telmisartan, on NVU and related inflammatory responses in SHR-SR with a low dose (0·3 mg/kg/day) only for improving metabolic syndrome, and a high dose (3 mg/kg/day) for improving both metabolic syndrome and SHR-SR hypertension.Results:Compared to normotensive Wistar rats, long-lasting hypertension in SHR-SR disrupted NVU by changing immunohistological components such as NAGO, collagen IV, astrocytes, and MMP-9. SHR-SR also strongly induced AD-related inflammasome NLRP3 in neuronal cells with age. However, such NVU disruption and inflammasome activation were greatly improved with dose-dependent telmisartan treatments.Discussion:These results suggest that telmisartan comprehensively protected the NVU components by reducing inflammatory reactions relative to AD in hypertensive rats, which could also preclude the risk of AD under hypertension.

Vibroacustic microvibrations enhance kidney blood supply, glomerular filtration and glutathione peroxidase activity in spontaneously hypertensive rats.

Limited numbers of studies include research of microvibration therapy in experimental models. We examined effects of chronic vibroacustic-microvibration treatment on haemodynamics and anti-oxidative defense in experimental hypertension. Study was performed on chronically treated hypertensive and normotensive Wistar rats. Mean arterial pressure (MAP), cardiac output (CO), renal blood flow (RBF), glomerular filtration and activity of anti-oxidative enzymes were determined after three weeks treatment. Vibroacustic treatment had no influence on MAP and CO, but RBF was increased in both groups of treated rats. Additionally, vibroacustic treatment enhanced diuresis and increased glomerular filtration in hypertensive rats. Glutathione peroxidase (GSH-Px) activity was elevated in both treated rat strains, but activity of superoxide dismutase was unchanged. We conclude that microvibration treatment doesn't ameliorate hypertension but improves renal blood supply (trough diminished renal vascular resistance), glomerular filtration, diuresis, and enhances glutathione dependent anti-oxidant defense with more important beneficials in hypertensive animals.

Reduced mechanical efficiency in left-ventricular trabeculae of the spontaneously hypertensive rat.

Long‐term systemic arterial hypertension, and its associated compensatory response of left‐ventricular hypertrophy, is fatal. This disease leads to cardiac failure and culminates in death. The spontaneously hypertensive rat (SHR) is an excellent animal model for studying this pathology, suffering from ventricular failure beginning at about 18 months of age. In this study, we isolated left‐ventricular trabeculae from SHR‐F hearts and contrasted their mechanoenergetic performance with those from nonfailing SHR (SHR‐NF) and normotensive Wistar rats. Our results show that, whereas the performance of the SHR‐F differed little from that of the SHR‐NF, both SHR groups performed less stress‐length work than that of Wistar trabeculae. Their lower work output arose from reduced ability to produce sufficient force and shortening. Neither their heat production nor their enthalpy output (the sum of work and heat), particularly the energy cost of Ca2+ cycling, differed from that of the Wistar controls. Consequently, mechanical efficiency (the ratio of work to change of enthalpy) of both SHR groups was lower than that of the Wistar trabeculae. Our data suggest that in hypertension‐induced left‐ventricular hypertrophy, the mechanical performance of the tissue is compromised such that myocardial efficiency is reduced.

Repeated phase shifts in the lighting regimen change the blood pressure response to norepinephrine stimulation in rats.

Disturbed circadian activity of the sympathetic system may be involved in negative consequences of chronodisruption on the cardiovascular system. We studied daily changes in pressure response to adrenergic stimulation in rats exposed to repeated phase advance shifts (PAS) of light/dark (LD) regimen. Blood pressure (BP), heart rate (HR) and locomotor activity was measured by radiotelemetry in normotensive Wistar rats exposed to repeated PAS (three 8-h shifts per week) lasting for 12 weeks. Norepinephrine was administered subcutaneously in the middle of L and D during week 12 of PAS exposure. In the control LD cycle, cardiovascular parameters exhibited significant daily rhythms with expected higher values during D than L phase. Rats exposed to PAS showed disturbed rhythms without a BP and HR increase. Administration of norepinephrine to control rats revealed daily variability in the cardiovascular response with higher stimulation of BP during L than D. This daily pattern of BP response to norepinephrine was diminished in the PAS group. The damped daily variability in pressure response to norepinephrine and augmented response during the light phase of the day suggest that the increased and desynchronized activity of the sympathetic system may worsen responses of the cardiovascular system to load in individuals exposed to irregular LD conditions.

Telmisartan Reduces Progressive Accumulation of Cellular Amyloid Beta and Phosphorylated Tau with Inflammatory Responses in Aged Spontaneously Hypertensive Stroke Resistant Rat

In addition to reducing the level of blood pressure (BP), telmisartan was expected to show the long-term neuroprotective effects preventing accumulation of cellular amyloid beta peptide (Aβ) and phosphorylated tau (pτ) by ameliorating neuroinflammation. We examined effects of telmisartan on cellular Aβ and pτ with inflammatory responses in the brain of a spontaneously hypertensive stroke resistant (SHR-SR) rat by giving either telmisartan at 0 (vehicle), .3 mg/kg/day or 3 mg/kg/day, orally, from 3 months of age and performed immunohistologic analysis at 6, 12, and 18 months. Compared with normotensive Wistar rats, numbers of Aβ- and pτ-positive neurons in the cerebral cortex progressively increased with age until 18 months in the SHR-SR rats, as did the numbers of ionized calcium-binding adapter molecule 1 (Iba-1)-positive microglia, tumor necrosis factor alpha (TNF-α)-positive neurons, and monocyte chemotactic protein 1 (MCP-1)-positive neurons. Low-dose telmisartan significantly decreased the numbers of Aβ- and pτ-positive neuron as well as the numbers of TNF-α-positive neurons, Iba-1-positive microglia, and MCP-1-positive neurons at 6, 12, and 18 months. High-dose telmisartan reduced BP and showed a further reduction of cellular Aβ and pτ. The present study suggests that accumulation of cellular Aβ and pτ and the inflammatory responses were decreased via improving metabolic syndrome with low-dose telmisartan and improving both metabolic syndrome and hypertension with high-dose telmisartan.

Deficient prolylcarboxypeptidase gene and protein expression in left ventricles of spontaneously hypertensive rats (SHR)

Prolylcarboxypeptidase (PRCP), an endothelial cell membrane serine peptidase that inactivates angiotensin II and activates pre-kallikrein, is thought to have anti-hypertensive and anti-proliferative roles in cardiovascular homeostasis. We hypothesized that PRCP function may be altered in heart tissue under conditions that predispose to left ventricle hypertrophy (LVH) in rats. We therefore used real-time PCR and western-blotting to examine the mRNA and protein expression of PRCP in the hearts of spontaneously hypertensive rats (SHR) at pre-hypertensive (5-week-old) and hypertensive (16-week-old) stages compared with age-matched hypertensive (2 kidney-1 clip; 2K-1C) rats and normotensive Wistar rats. PRCP mRNA expression was significantly reduced in hearts of 5- and 16-week-old SHR compared with age-matched Wistar controls, 2K-1C hypertensive rats and sham-operated normotensive rats. There were no significant differences in the PRCP mRNA and protein expression levels in hearts from hypertensive renovascular and sham-operated normotensive rats. Prolonged treatment of SHR with the AT1 receptor antagonist losartan (40mg/kg, gavage for 8 weeks) reduced the left ventricular weight/body weight ratio (LVW/BW), as well as the mRNA expression of collagen type 1, collagen type 3 and MMP9 in left ventricular tissue, without affecting PRCP gene and protein expression. Our results suggest that diminished PRCP gene and protein expression might be constitutionally involved in the SHR phenotype. In addition, since neither the development of arterial hypertension in the 2K-1C model nor its successful treatment in SHR altered PRCP gene and protein expression in heart tissue, it appears unlikely that PRCP function is regulated by the renin–angiotensin system or by afterload conditions.

Strong Reduction of Low-Density Lipoprotein Receptor/Apolipoprotein E Expressions by Telmisartan in Cerebral Cortex and Hippocampus of Stroke Resistant Spontaneously Hypertensive Rats

Telmisartan is a unique angiotensin II type 1 receptor blocker with a partial peroxisome proliferator-activated receptor-γ (PPARγ) agonistic property to exert not only antihypertensive effect but also antimetabolic syndrome effect. We examined the long-term effect of telmisartan on cholesterol transport-related proteins (low-density lipoprotein receptor [LDL-R]/apolipoprotein E [ApoE]) and microtubule-associated proteins 2 (MAP2) in the brains of stroke resistant spontaneously hypertensive rats (SHR-SRs), which were divided into 3 experiment groups including vehicle group (SHR/Ve), low-dose telmisartan group (SHR/Low, .3 mg/kg/day), and high-dose telmisartan group (SHR/High, 3 mg/kg/day). The numbers of LDL-R- and immuno-ApoE-positive neurons increased in both cerebral cortex and hippocampus of SHR/Ve throughout 6, 12, and 18 months of age, compared with age-matched normotensive Wistar rats. On the other hand, telmisartan significantly reduced the numbers of LDL-R- and ApoE immuno-positive neurons in both cerebral cortex and hippocampus, with similar effectiveness in the SHR/Low group without blood pressure (BP) lowering to BP lowering (SHR/High). The decrease of MAP2-positive neuron in SHR/Ve was recovered by telmisartan in both cerebral cortex and hippocampus. These findings suggest that a long-term treatment with telmisartan directly improved neuronal lipid metabolism in the cerebral cortex and hippocampus of SHR-SR, mainly improving LDL-R and ApoE metabolism (SHR/Low) with a small additive benefit by BP lowering (SHR/High), which could provide a preventative approach in patients with hypertension at risk of Alzheimer disease.

Healing Process of Autogenous Bone Graft in Spontaneously Hypertensive Rats Treated With Losartan: An Immunohistochemical and Histomorphometric Study

Hypertension is a major risk factor for cardiovascular diseases, which has been related to such changes as gradual bone loss and a decrease in bone mass index. The cellular and molecular mechanisms that involve hypertension and osteoporosis are not fully understood. Many patients have high blood pressure, controlled or uncontrolled, and may use at least 1 antihypertensive drug, and an understanding of the interference of hypertension with bone healing is very important when considering oral rehabilitation with implants and bone grafts. This study investigated the interference of hypertension in bone metabolism during the repair process of autogenous bone grafting and analyzed the influence of losartan, an antihypertensive drug and angiotensin II receptor antagonist, through histometric and immunohistochemical analyses by examining the protein expressions of osteocalcin, osteoprotegerin, receptor activator of nuclear factor-κB, receptor activator of nuclear factor-κB ligand, tartrate-resistant acid phosphatase, vascular endothelial growth factor, and platelet endothelial cell adhesion molecule. The groups studied include 24 normotensive Wistar rats and 24 spontaneously hypertensive rats divided into groups treated and not treated with losartan. Rats were subjected to block bone graft surgery in the mandible and were sacrificed at 7, 14, and 28 days. Histometric analysis was performed to evaluate the amount of bone tissue formed at the interface of the recipient bed and bone graft. The total area of formed bone tissue was outlined and calculated. Immunohistochemical analysis was semi-quantitative and the significance of the differences between groups regarding the percentage of newly formed bone tissue interface and protein expression were determined by ANOVA analysis of variance and Kruskall-Wallis followed by Tukey test or Holm Sidak to detect differences between groups. The results were considered statistically significant when P<.05. The untreated hypertensive rats showed a delay in the repair of autogenous bone block grafts compared with untreated Wistar rats. Furthermore, the use of losartan for lowering blood pressure in these animals was shown to improve the healing process, despite not showing important statistical differences.

Маркери ремоделювання міокарда щурів при артеріальній гіпертензії та експериментальному цукровому діабеті: роль мітохондріальної дисфункції

The expression of cardiotrophin-1, annexin V, titin and type I collagen was investigated in myocardium of normotensive Wistar rats and spontaneous hypertensive rats with and without experimental diabetes. The Ca(2+)-induced mitochondrial permeability transition pore was assessed in mitochondria isolated from rat hearts. The contents of cardiotrophin-1, annexin V and type I collagen in spontaneous hypertensive rats with diabetes were higher compared with that detected in the groups of normotensive rats and rats with diabetes. The cardiac titin level was 27% lower in animals with hypertension and diabetes compared to spontaneous hypertensive rats without diabetes. The changes of cardiotrophin-1, annexin V, titin and type I collagen expression were associated with higher sensitivity of mitochondrial pore to Ca2+ in myocardium of spontaneous hypertensive rats with diabetes.

A flavonoid fraction purified from Rutaceae aurantiae (DaflonR) inhibiting AGE formation, reduces urinary albumin clearance and corrects hypoalbuminemia in normotensive and hypertensive diabetic rats

AimAdvanced glycation endproducts (AGEs) have been shown to contribute to alteration of glomerular permselectivity to proteins in diabetes. Oxidative stress is required for AGE formation. Therefore we studied the effect of an antioxidant micronized purified flavonoid fraction (MPFF, DaflonR 500mg), on urinary albumin clearance in diabetic rats. MethodsHyperglycaemia was induced by streptozotocin 55mg/kg IM at days 0 and 7 in normotensive Wistar rats (NWR, diabetes duration 5 months) or hypertensive Wistar Kyoto rats (SHR, diabetes duration 2 months). MPFF was administered at 300mg/kg/day, from day −2 until sacrifice. ResultsAfter 5 months of diabetes in NWR, MPFF reduced albumin clearance from 729±92 to 392±60nl/min/kg, p<0.01, and restored albuminemia from 20.4±0.9 to 24.0±1g/l, p<0.05; albumin fractional clearance was significantly diminished in the flavonoid-treated diabetic rats (0.360±0.037‰ versus 1.335±0.430‰ in the diabetic controls, p<0.001); MPFF did not significantly modify blood glucose and plasma fructosamine levels. After 2 months of diabetes in SHR, MPFF reduced albumin clearance from 243±121 to 101±47nl/min/kg, p<0.05, and restored albuminemia from 21.1±1.6 to 26.7±2.2g/l (p<0.05); MPFF also decreased plasma fluorescence characteristic of AGEs (p<0.02). Besides hesperetin, a main metabolite of MPFF recovered in plasma, inhibited in vitro the formation of the crosslinking AGE pentosidine in collagen incubated with high glucose (p<0.001). ConclusionOur results confirm the role of glycoxidative stress in diabetic nephropathy. MPFF might be useful as complementary treatment for preventing diabetic microangiopathy.

Effect of Ang II on angiotensinogen expression levels in hypertensive rat astrocytes (1140.1)

Objective: To investigate the effects of Angiotensin II (Ang II) on Angiotensinogen (AGT) mRNA and protein levels in spontaneous hypertensive rats (SHR) astrocytes. Background: AGT is the precursor molecule for the synthesis of Ang II produced by the renin angiotensin system (RAS). Astrocytes are the major source of AGT in the brain, and regulation of brain AGT levels alters blood pressure and electrolyte homeostasis. In this study, SHR were used as a genetic hypertension model and the results were compared to normotensive Wistar rats. Methods: Astrocytes isolated from neonatal rat’s cerebellum (CB) and brainstem (BS) regions were treated with 100nM Ang II, and the time‐dependent effect of Ang II on AGT protein and mRNA levels were measured using Western blotting and quantitative polymerase chain reaction techniques, respectively. Results: Ang II significantly increased AGT protein levels but, decreased AGT mRNA levels over most time points examined in BS and CB Wistar and SHR astrocytes. There was no significant difference between Ang II’s ability to affect AGT protein and mRNA levels in SHR as compared to Wistar astrocytes. Conclusions: These findings showed that Ang II regulates it’s synthesis by inducing basal AGT protein and mRNA levels. Further, the ability of astrocytes to produce AGT may not be contributing to the hypertensive state in the SHR model. Grant Funding Source: Supported by Nova Southeastern University Chancellor's Faculty Research &amp; Development Grant # 335872

Modulation of the cannabinoid‐1 receptor by angiotensin II in astrocytes isolated from spontaneously hypertensive rats (1140.8)

Objective: To determine whether a mediator of neuroprotection, the Cannabinoid Type 1 receptor (CB1R), is altered by Angiotensin (Ang) II in astrocytes. Background: Along with an elevated Ang II level, neuroinflammation in the brainstem (BS) has been shown to shift the balance towards an augmented sympathetic drive, the latter being associated with hypertension. Astrocytes play a central role in the bidirectional modulation of inflammation Methods: BS astrocytes isolated from Spontaneously Hypertensive Rats (SHR) were used as a hypertension model to determine whether Ang II induces CB1R protein and mRNA expression. The results were compared to normotensive Wistar rats. The cells were treated with 100nM Ang II in a time‐dependent manner, and the effect of Ang II on CB1R protein and mRNA levels were measured using Western blotting and qt‐PCR techniques, respectively. Results: In Wistar cells, Ang II increased the CB1R protein and mRNA levels in a time‐dependent manner. In SHR astrocytes, Ang II down‐regulated or had no effect on CB1R protein and mRNA levels. Compared with Wistar astrocytes, the CB1R protein and mRNA levels in SHR astrocytes were significantly different. Conclusion: Our findings suggest that the CB1R is differentially regulated in SHR versus normotensive astrocytes. This interaction may serve as a potential target to restore an elevated sympathetic drive in hypertension.Grant Funding Source: NSU PFRDG 2013‐14: Grant # 335309