Ubiquinol-cytochrome-c reductase 7.2 kDa protein of mitochondrial complex III is steroid-responsive and increases in cardiac hypertrophy and hypertension

Women and men do not respond identically to cardiac insults; premenopausal women are somewhat protected from cardiovascular disease. Our objective was to isolate and characterize hormone-responsive genes in the heart. Differential display identified an estrogen-inducible fragment that was found to encode the ubiquinol-cytochrome-c reductase (UCCR) 7.2 kDa protein of the mitochondrial respiratory complex III. We found UCCR7.2 mRNA to be highly expressed in the heart, and this expression increased in hearts of 4-, 10-, and 28-week-old spontaneously hypertensive rats (SHR) compared with normotensive Wistar-Kyoto rats. Oral hydralazine treatment to reduce hypertension reduced SHR UCCR7.2 expression. Cardiac UCCR7.2 mRNA expression was also increased significantly after a 5/6 nephrectomy compared with mock surgery. Cardiac expression after ovariectomy was 50% that of intact rats. Supplementation of ovariectomized rats with estrogen had no effect, whereas progesterone increased cardiac expression, although not to intact levels. No change in cardiac UCCR7.2 expression was found when intact rats were treated with either tamoxifen or ICI 182780. Thus, UCCR7.2 expression is reduced in the absence of ovarian hormones, but is not directly regulated by estrogen in the heart. We conclude that UCCR7.2 is a steroid hormone-responsive gene in the heart, with expression increased in cardiac hypertrophy and in response to hypertension.     

17 beta-Estradiol may affect vulnerability of striatum in a 3-nitropropionic acid-induced experimental model of Huntington's disease in ovariectomized rats

The aim of present study was to clarify the role of female sex hormones in the development and course of neurodegenerative disease in an experimental model of Huntington's disease induced by 3-nitropropionic acid (NPA) (30 mg/kg intraperitoneally (i.p.)/day for 4 days) in ovariectomized rat. Gonadectomy prompted oxidative stress and cell death evaluated by the detection of caspase-3, whereas 3-nitropropionic acid enhanced the oxidative stress induced by ovariectomy and it triggered cell damage characterized by increases of LDH levels. These changes were prevented by administration of 17 beta-estradiol. Our findings suggested that: (i) ovariectomy induced oxidative stress and apoptosis in the brain; (ii) 3-nitropropionic acid exacerbated oxidative stress induced by ovariectomy and shifting cell to cell death; and (iii) 17 beta-estradiol administration decreased oxidative stress and cell death induced by ovariectomy and 3-nitropropionic acid. These results revealed that sex ovarian hormones play a important role in onset and development of neurodegenerative diseases, as well as neuroprotective effects of 17 beta-estradiol against the changes induced ovariectomy and ovariectomy plus 3-nitropropionic acid.     

Evaluation of the role of calcitonin deficiency in ovariectomy-induced osteopenia

Studies were carried out in rats to examine the role of calcitonin deficiency in the pathogenesis of ovariectomy-induced osteopenia. The parathyroid glands of 80 female Wistar rats were autotransplanted to their thigh muscle and the animals divided into 4 groups. Group 1 rats were sham ovariectomized, and thyroidectomized to make them calcitonin deficient; Group 2 rats were thyroidectomized, and ovariectomized to make them deficient in ovarian hormones as well; Group 3 rats were sham thyroidectomized and sham ovariectomized, and Group 4 rats were sham thyroidectomized and ovariectomized. A fifth group of rats were unoperated upon and served as controls. Thyroidectomized animals were maintained on thyroxine replacement and 11 months after ovariectomy all the animals were bled, killed and their femurs dissected out. In both the thyroid intact and thyroidectomized animals, ovariectomy decreased femur density significantly (P less than 0.01). Similarly, ovariectomy resulted in a decrease in femur calcium (P less than 0.01) in both groups of animals, and in a significant decrease in serum calcitonin (P less than 0.05) in the thyroid intact animals. We conclude from these findings that ovarian hormone deficiency can cause bone loss independently of lowering circulating calcitonin levels.     

Nitric oxide at the CVLM is involved in the attenuation of the reflex bradycardia in renovascular hypertensive rats

Hypertension is associated to an increase in central oxidative stress and an attenuation of the baroreflex control of arterial pressure. The present study evaluated the effect of alterations in the levels of nitric oxide (NO) and superoxide anion in the caudal ventrolateral medulla (CVLM), a key area of the brainstem for the baroreflex control of arterial pressure, in renovascular hypertensive rats (2K1C). Baseline mean arterial pressure (MAP), heart rate (HR), and reflex bradycardia were evaluated 30 days after renal artery occlusion in anesthetized (urethane, 1.2 g/kg, i.p.) 2K1C or normotensive (SHAM) rats. The MAP, HR, and baroreflex control of HR were evaluated before and after CVLM microinjections of the non-selective NOS inhibitor L-NAME (10 nmol), the NO precursor L-ARG (50 nmol), or the antioxidant ascorbic acid, Vit C (10 nmol). In both 2K1C and SHAM animals, CVLM microinjection of L-NAME produced a decrease in MAP, whereas L-ARG induced a significant increase in MAP. However, microinjection of Vit C into the CVLM produced a decrease in MAP and HR only in 2K1C and not in SHAM rats. Cardiovascular effects produced by microinjection of l-ARG into the CVLM were abolished by prior microinjection of L-NAME in the CVLM of 2K1C and SHAM rats. Microinjection of L-NAME into the CVLM increased the sensitivity of reflex bradycardia in 2K1C animals. In contrast, the CVLM microinjection of L-ARG reduced reflex bradycardia only in SHAM rats. Vit C in the CVLM did not change reflex bradycardia in either 2K1C or in SHAM rats. These results suggest that increased oxidative stress in the CVLM during hypertension contributes to the reduced baroreflex sensitivity and to maintain hypertension in the 2K1C model.     

Exercise training restores oxidative stress and nitric oxide synthases in the rostral ventrolateral medulla of renovascular hypertensive rats

Abstract

We hypothesize that exercise training (EX) reverses the level of nitric oxide (NO) and oxidative stress into rostral ventrolateral medulla (RVLM) of renovascular hypertensive rats (two kidneys, one clip - 2K1C). Microinjections of L-arginine (5 nmol), L-NAME (10 nmol), or saline (100 nl) were made into RVLM of 2K1C and normotensive (SHAM) rats sedentary (SED) or subjected to swimming for 4 weeks. mRNA expression (by qRT-PCR) of nitric oxide synthases isoforms (nNOS, eNOS, and iNOS), manganese superoxide dismutase (MnSOD), copper and zinc superoxide (Cu/ZnSOD), catalase (CAT), NADPH oxidase subunit p22^phox, concentration of thiobarbituric acid-reactive substances (TBARS), and CAT activity into RVLM were evaluated. The mean arterial pressure was reduced in 2K1C EX compared with that in 2K1C SED rats. L-arginine into RVLM induced hypertensive effect in 2K1C and SHAM SED rats, while L-NAME prevented hypertensive effect only in SHAM-SED. EX reduced hypertensive effect of L-arginine in SHAM and 2K1C rats. mRNA expression of NOS isoforms, p22^phox, and concentration of TBARS were increased while CAT and Cu/ZnSOD expression and CAT activity decreased into RVLM of 2K1C-SED compared with SHAM-SED rats. Additionally, EX reversed mRNA expression of CAT and NOS isoforms, concentration of TBARS, and CAT activity into RVLM of 2K1C-EX rats. These data suggest that the levels of NOS and oxidative stress into RVLM are important to determine the level of hypertension. Furthermore, EX can restore the blood pressure by reversing the levels of NOS and CAT expression, and reducing TBARS concentration into RVLM for the physiological state.     

Effect of beta-adrenergic and renin-angiotensin system blockade on myocyte apoptosis and oxidative stress in diabetic hypertensive rats

Diabetes aggravates the clinical severity and represents an additional independent risk factor of hypertension. Since both diseases separately concur to cardiomyocyte apoptosis, a mechanism at least partly involving unbalanced oxidative stress, we investigated whether the combination of diabetes and hypertension potentiated cardiac cell death in experimental models, compared to either disease alone. We also evaluated the short-term effects of different drugs in these models. Streptozotocin-induced diabetic normotensive (WKY) or hypertensive (SHR) rats were treated for one week with a DA(2)/alpha(2) agonist (CHF-1024), a selective beta1 adrenergic blocker (metoprolol), an angiotensin II-receptor blocker (valsartan) or a radical scavenger (tempol). In separate experiments, isolated cardiomyocytes were cultured in high glucose medium (25 mM) containing the same drugs. Although the number of apoptotic cardiomyocytes and the myocardial density of oxygen radicals were higher in non diabetic hypertensive than in normotensive controls, diabetes raised these variables to comparable absolute levels in both strains. All drugs except metoprolol significantly reduced apoptosis and oxidative stress in the diabetic animals of both strains and in the isolated myocytes cultured with high glucose. In conclusion, hypertensive rat is no more susceptible than its normotensive control to acute apoptosis induced by diabetes. Oxidative stress might be considered the common trigger for cardiac myocyte apoptosis in both conditions.     

Sodium nitrite downregulates vascular NADPH oxidase and exerts antihypertensive effects in hypertension

Dietary nitrite and nitrate are important sources of nitric oxide (NO). However, the use of nitrite as an antihypertensive drug may be limited by increased oxidative stress associated with hypertension. We evaluated the antihypertensive effects of sodium nitrite given in drinking water for 4 weeks in two-kidney one-clip (2K1C) hypertensive rats and the effects induced by nitrite on NO bioavailability and oxidative stress. We found that, even under the increased oxidative stress conditions present in 2K1C hypertension, nitrite reduced systolic blood pressure in a dose-dependent manner. Whereas treatment with nitrite did not significantly change plasma nitrite concentrations in 2K1C rats, it increased plasma nitrate levels significantly. Surprisingly, nitrite treatment exerted antioxidant effects in both hypertensive and sham-normotensive control rats. A series of in vitro experiments was carried out to show that the antioxidant effects induced by nitrite do not involve direct antioxidant effects or xanthine oxidase activity inhibition. Conversely, nitrite decreased vascular NADPH oxidase activity. Taken together, our results show for the first time that nitrite has antihypertensive effects in 2K1C hypertensive rats, which may be due to its antioxidant properties resulting from vascular NADPH oxidase activity inhibition.     

Hypersensitivity to acute ANG II in female growth-restricted offspring is exacerbated by ovariectomy

Female growth-restricted offspring are normotensive in adulthood. However, ovariectomy induces a marked increase in mean arterial pressure (MAP) that is abolished by renin angiotensin system (RAS) blockade, suggesting RAS involvement in the etiology of hypertension induced by ovariectomy in adult female growth-restricted offspring. Blockade of the RAS also abolishes hypertension in adult male growth-restricted offspring. Moreover, sensitivity to acute ANG II is enhanced in male growth-restricted offspring. Thus, we hypothesized that an enhanced sensitivity to acute ANG II may contribute to hypertension induced by ovariectomy in female growth-restricted offspring. Female offspring were subjected to ovariectomy (OVX) or sham ovariectomy (intact) at 10 wk of age. Cardio-renal hemodynamic parameters were determined before and after an acute infusion of ANG II (100 ng·kg(-1)·min(-1) for 30 min) at 16 wk of age in female offspring pretreated with enalapril (40 mg·kg(-1)·day(-1) for 7 days). Acute ANG II induced a significant increase in MAP in intact growth-restricted offspring (155 ± 2 mmHg, P < 0.05) relative to intact control (145 ± 4 mmHg). Ovariectomy augmented the pressor response to ANG II in growth-restricted offspring (163 ± 2 mmHg, P < 0.05), with no effect in control (142 ± 2 mmHg). Acute pressor responses to phenylephrine did not differ in growth-restricted offspring relative to control, intact, or ovariectomized. Furthermore, renal hemodynamic responses to acute ANG II were significantly enhanced only in ovariectomized female growth-restricted offspring. Thus, these data suggest that enhanced responsiveness to acute ANG II is programmed by intrauterine growth restriction and that sensitivity to acute ANG II is modulated by ovarian hormones in female growth-restricted offspring.     

Cardiac norepinephrine release: modulation by ovariectomy and estrogen

Previously, we have demonstrated that in contrast to male rats, female rats do not show an age-related reduction of depolarization-elicited norepinephrine (NE) release from cardiac synaptosomes (resealed nerve terminals). These results suggest that sex hormones such as estrogen may modulate NE release from cardiac synaptosomes prepared from female rats. The present study was designed to test the hypotheses that long-term estrogen depletion, resulting from ovariectomy, and estrogen replacement alters depolarization-elicited NE release from cardiac synaptosomes. Female F344 rats were divided into two groups, one of which underwent bilateral ovariectomy, whereas the other underwent a sham operation. Three ovariectomized subgroups received daily injections of conjugated equine estrogens, delta8,9-dehydroestrone or 17 alpha-dihydroequilenin. Another ovariectomized control subgroup and the sham-operated animals received daily injections of vehicle. After 90 or 270 days of treatment, the animals were sacrificed. Cardiac synaptosomes were prepared from each heart, incubated with [(3)H]-NE, and used to evaluate NE release capacity by exposure to 50 mM K(+). The effectiveness of the ovariectomy and the estrogenic actions of the test compounds was confirmed by evaluating vaginal smears, determining uterine weights, and measuring serum luteinizing hormone (LH) concentrations. Ovariectomy (after both 90 and 270 days) significantly increased depolarization-induced NE release compared with sham-operated rats. Treatment with all three estrogenic preparations reduced NE release in ovariectomized rats to values similar to those observed in sham-operated animals. Interestingly, NE release rates from rats treated with conjugated estrogens for 270 but not 90 days were significantly below that observed in age-matched sham animals. These results demonstrate that estrogen modulates depolarization-elicited NE release from cardiac nerve terminals. Such modulation may represent a protective action by estrogen at the cardiac synapse.     

Time course involvement of matrix metalloproteinases in the vascular alterations of renovascular hypertension

Increased vascular matrix metalloproteinases (MMPs) levels play a role in late phases of hypertensive vascular remodeling. However, no previous study has examined the time course of MMPs in the various phases of two-kidney, one-clip hypertension (2K1C). We examined structural vascular changes, collagen and elastin content, vascular oxidative stress, and MMPs levels/activities during the development of 2K1C hypertension. Plasma angiotensin converting enzyme (ACE) activity was measured to assess renin-angiotensin system activation. Sham or 2K1C hypertensive rats were studied after 2, 4, 6, and 10weeks of hypertension. Systolic blood pressure (SBP) was monitored weekly. Morphometry of structural changes in the aortic wall was studied in hematoxylin/eosin, orcein and picrosirius red sections. Aortic NADPH activity and superoxide production was evaluated. Aortic gelatinolytic activity was determined by in situ zymography, and MMP-2, MMP-14, and tissue inhibitor of MMPs (TIMP)-2 levels were determined by gelatin zymography, immunofluorescence and immunohistochemistry. 2K1C hypertension was associated with increased ACE activity, which decreased to normal after 10 weeks. We found increased aortic collagen and elastin content in the early phase of hypertension, which were associated with vascular hypertrophy, increased vascular MMP-2 and MMP-14 (but not TIMP-2) levels, and increased gelatinolytic activity, possibly as a result of increased vascular NADPH oxidase activity and oxidative stress. These results indicate that vascular remodeling of renovascular hypertension is an early process associated with early increases in MMPs activities, enhanced matrix deposition and oxidative stress. Using antioxidants or MMPs inhibitors in the early phase of hypertension may prevent the vascular alterations of hypertension.     

Targeted activation of transcription in vivo through hairpin-triplex forming oligonucleotide in Saccharomyces cerevisiae

The aims of the present study were to analyse the effects of an oral daily dose (10 mg/kg) of the dietary flavonoid quercetin for five weeks in two-kidney, one-clip (2K1C) Goldblatt (GB) hypertensive rats. The evolution of systolic blood pressure was followed by weekly measurements, and morphological variables, proteinuria, plasma nitrates plus nitrites (NO_x) and thiobarbituric acid reactive substances (TBARS), liver oxidative stress markers and endothelial function were determined at the end of the experimental period. Quercetin treatment reduced systolic blood pressure of GB rats, producing no effect in control animals. It also reduced cardiac hypertrophy and proteinuria developed in GB hypertensive rats. Decreased endothelium-dependent relaxation to acetylcholine of aortic rings from GB rats was improved by chronic quercetin treatment, as well as increased endothelium-dependent vasoconstrictor response to acetylcholine and overproduction of TXB₂ by aortic vessels of GB rats, being without effect in normotensive animals. Increased plasma NO_x and TBARS, and decreased liver total glutathione (GSH) levels and glutathione peroxidase (GPX) activity were observed in GB hypertensive rats compared to the control animals. Normalisation of plasma NO_x and TBARS concentrations and improvement of the antioxidant defences system in liver accompanied the antihypertensive effect of quercetin. We conclude that chronic oral treatment with quercetin shows both antihypertensive and antioxidant effects in this model of renovascular hypertension. (Mol Cell Biochem 270: 147–155, 2005)M.F. García-Saura and M. Galisteo are equal contributors to this work     

Angiotensinase activities in the kidney of renovascular hypertensive rats

In spite of the well-known contribution of angiotensin II (Ang II) in the pathogenesis of Goldblatt two-kidney one clip (G2K1C) hypertension, the importance of other Ang peptides, such as Ang III, Ang IV or Ang 2-10, is scarcely understood. The functional status of these peptides depends on the action of several aminopeptidases called angiotensinases. The metabolism of Ang III to Ang IV by aminopeptidase M (AlaAP) and of Ang I to Ang 2-10 by aspartyl aminopeptidase (AspAP) was evaluated in the renal cortex and medulla of normotensive (Sham-operated) and hypertensive (G2K1C) rats, treated or not with the AT(1) receptor antagonist valsartan. The results demonstrated a highly significant increase of membrane-bound (MEMB) AlaAP in the cortex of the non-ischemic kidney of G2K1C rats compared with the kidney of normal rats and with the clipped kidney of G2K1C rats. This suggests an increased formation of Ang IV in the non-clipped kidney of G2R1C rats. Valsartan reduced MEMB AlaAP and AspAP activities in the renal cortex of normotensive and in the clipped kidney of hypertensive rats. The reduced metabolism of Ang III may prolong its half-life in valsartan-treated animals. These results suggest a role for AlaAP in renovascular hypertension. In addition, the higher AspAP activity of the renal cortex compared to medulla reflects its relative functional difference between both locations.     

Estrogen supplement prevents the calcium hypersensitivity of cardiac myofilaments in ovariectomized rats

Our previous biochemical and mechanical studies have demonstrated an increase in Ca2+ sensitivity of cardiac myofilaments in ovariectomized rats. To test whether the body weight gain associated with ovariectomy contributed some effects to the changes in myofibrillar functions, the relations of pCa (-log Ca2+ molar concentration) to actomyosin adenosine triphosphatase (ATPase) activity of isolated myofibrillar preparations from 10-week pair-fed ovariectomized rats were compared with those from sham-operated controls. Despite similar body weights, the maximum myofibrillar ATPase activity was significantly lower in pair-fed ovariectomized rats as compared to that of sham-operated controls. In addition, the pCa-actomyosin ATPase relationship of pair-fed ovariectomized hearts still demonstrated a significant leftward shift in pCa50 (-log half-maximally Ca2+ activation) from that of sham-operated controls. To find out which hormone was responsible for the observed increase in myofibrillar Ca2+ sensitivity, different sex hormone supplemental regimens were administered to ovariectomized rats. Subcutaneous injection of estrogen (5 microg/rat) or estrogen plus progesterone (1 mg/rat) three times a week could effectively prevent the changes in body weight, heart weight, and uterine weight of the ovariectomized animals. Moreover, supplements of either estrogen or progesterone could prevent a decrease in maximum ATPase activity. In contrast, only the estrogen replacement could abolish the Ca2+ hypersensitivity of the myofilaments in these ovariectomized rats. These results suggest differential cardio-regulatory effects of ovarian sex hormones on the Ca2+ activation of the myofilaments.     

The nonpeptide ANG-(1–7) mimic AVE 0991 attenuates cardiac remodeling and improves baroreflex sensitivity in renovascular hypertensive rats

AimsThe nonpeptide Ang-(1–7) analog, AVE 0991, is recognized as having beneficial cardiovascular effects similar to those induced by Ang-(1–7). In this study, we evaluated the effects of AVE 0991 on cardiovascular functions and on cardiac and renal remodeling in rats with 2K1C renovascular hypertension.Main methodsFisher rats underwent surgery to induce 2K1C renovascular hypertension and were then treated with AVE 0991 (1 or 3 mg/kg) for 28 days. At the end of treatment, the blood pressure (BP), heart rate (HR), and baroreflex sensitivity were evaluated, in conscious animals. The rats were then euthanized and the heart and kidneys removed for subsequent histological analysis.Key findingsTreatment with AVE 0991 in 2K1C rats restored the baroreflex sensitivity of both bradycardic and tachycardic components to levels comparable to those of normotensive SHAM rats. At a higher dose (3 mg/kg), AVE 0991 was also anti-hypertensive in 2K1C rats. Furthermore, AVE 0991 reduced the heart weight, thickness of myocardial fibers, number of inflammatory cells, and area of collagen deposition in the hearts of 2K1C rats compared to SHAM rats. The inflammatory process and tissue area of collagen deposition were decreased in the clipped kidney of AVE 0091-treated 2K1C rats.SignificanceOur data showed that oral treatment with AVE 0991 reduces blood-pressure cardiac remodeling and improves baroreflex sensitivity in 2K1C renovascular hypertensive rats.     

Effects of sex hormone levels on aortic vascular reactivity and variables associated with the metabolic syndrome in sucrose-fed female rats

We studied the effect of varying levels of sex hormones, induced by ovariectomy and administration of testosterone or estradiol, on aortic reactivity in female rats with metabolic syndrome (MS) induced by a sucrose diet. Vasoreactivity of aortic rings, blood pressure, intra-abdominal fat, serum triglycerides, nitrates and nitrites, and TBARS were evaluated. Intact MS and ovariectomized MS had higher BP than intact control (C) and ovariectomized C, respectively; estradiol administration decreased BP in ovariectomized MS but not in ovariectomized C. Triglycerides and fat were both higher in MS. Triglycerides were not modified by surgery or hormone treatment, but ovariectomy increased fat. When ovariectomy was combined with hormones, however, fat was reduced to the level of intact rats. Ovariectomy decreased, but hormones increased, serum nitrates and nitrites. Vasoconstriction was larger in intact MS and ovariectomized MS + testosterone aortas than in intact C and ovariectomized C + testosterone, respectively. Vasodilation was reduced in intact MS and ovariectomized MS + testosterone compared with intact C, ovariectomized C + testosterone, ovariectomized MS, and ovariectomized MS + estradiol. The results suggest endothelial dysfunction in intact MS and ovariectomized MS + testosterone, but protection by ovariectomy + estradiol in MS due to hormones. Indomethacin reduced all contractions, but the effect was greater in estradiol-treated rats. L-NAME increased contractility, more in the ovariectomized C and MS groups and less in the estradiol-treated groups.     

Effect of hypertension and its reverse on serum nitric oxide concentration and vascular permeability in two-kidney one-clip hypertensive rats

The aim of this study was to evaluate the effect of hypertension and its reverse on serum nitric oxide (NO) concentration and endothelial permeability in two-kidney one-clip (2K1C) hypertensive rats. 28 male Wistar rats were divided into four groups: 1) 2K1C for 12 weeks; 2) sham-clipped for 12 weeks; 3) 2K1C for 12 weeks and unclipped for 12 weeks; 4) sham-clipped for 12 weeks and unclipped for 12 weeks. Blood samples were taken before experiment, 12th week and 24th week (in groups 3 and 4). Coronary vascular and aortic endothelial permeability were determined by extravasation of Evans blue dye method. Serum NO level was significantly lower in hypertensive group compare with sham group (4.21 ± 1.28 vs. 9.47 ± 1.34 μmol/l, respectively). Reversal of hypertension did not improve serum NO concentration in 2K1C group (4.21 ± 1.28 vs. 4.32 ± 1.34 μmol/l). Coronary vascular and aortic endothelial permeability were not different between hypertensive and normotensive groups and reversal of hypertension did not alter endothelial permeability. Lower serum NO concentration in 2K1C hypertensive rats even after reversal of hypertension suggested that in addition to NO, other mechanisms could be involved in surgical reversal of hypertension. Hypertension and its reverse did not change endothelial permeability at least in this model of hypertension.     

Sexual Dimorphism in Development of Kidney Damage in Aging Fischer-344 Rats

BackgroundAging kidneys exhibit slowly developing injury and women are usually protected compared with men, in association with maintained renal nitric oxide.ObjectivesOur purpose was to test 2 hypotheses: (1) that aging intact Fischer-344 (F344) female rats exhibit less glomerular damage than similarly aged males, and (2) that loss of female ovarian hormones would lead to greater structural injury and dysregulation of the nitric oxide synthase (NOS) system in aging F344 rat kidneys.MethodsWe compared renal injury in F344 rats in intact, ovariectomized, and ovariectomized with estrogen replaced young (6 month) and old (24 month) female rats with young and old intact male rats and measured renal protein abundance of NOS isoforms and oxidative stress.ResultsThere was no difference in age-dependent glomerular damage between young or old intact male and female F344 rats, and neither ovariectomy nor estrogen replacement affected renal injury; however, tubulointerstitial injury was greater in old males than in old females. These data suggest that ovarian hormones do not influence these aspects of kidney aging in F344 rats and that the greater tubulointerstitial injury is caused by male sex. Old males had greater kidney cortex NOS3 abundance than females, and NOS1 abundance (alpha and beta isoforms) was increased in old males compared with both young males and old females. NOS abundance was preserved with age in intact females, ovariectomy did not reduce NOS1 or NOS3 protein abundance, and estrogen replacement did not uniformly elevate NOS proteins, suggesting that estrogens are not primary regulators of renal NOS abundance in this strain. Nicotinamide adenine dinucleotide phosphate oxidase-dependent superoxide production and nitrotyrosine immunoreactivity were increased in aging male rat kidneys compared with females, which could compromise renal nitric oxide production and/or bioavailability.ConclusionsThe kidney damage expressed in aging F344 rats is fairly mild and is not related to loss of renal cortex NOS3 or NOS1 alpha.     

Combined effects of hypertension and conditioning on coronary vascular reserve in rats

To evaluate the combined effects of cardiac overload imposed by hypertension and chronic swim training on coronary vascularity, female rats were made hypertensive by unilateral renal artery stenoses and were exercised in an 8- to 10-wk swimming program. Maximal coronary flow was assessed in isolated retrograde buffer-perfused hearts under conditions of minimal coronary resistance (15 microM adenosine or anoxia). Sedentary normotensive animals, sedentary hypertensive animals, and normotensive animals exposed to a swimming program were also studied. Swimming was associated with an 18% increase in heart weight and with increases in both absolute (ml/min) and relative (ml X g-1 X min-1) maximal coronary flow. Hypertension was associated with a 32% increase in heart weight but with a decrease in absolute and relative coronary flow compared with controls. The combined stimuli resulted in a 63% myocardial hypertrophy and a 19% increase in absolute flow. Relative coronary flow (g tissue-1) was similar in hearts from hypertensive sedentary animals and hypertensive swimmers. These data indicate that the coronary vascular deficit that accompanies the cardiac hypertrophy of hypertension is not worsened by the superimposition of an exercise load that exaggerates the hypertrophy.     

The Influence of Early Life Interventions on Olfactory Memory Related to Palatable Food, and on Oxidative Stress Parameters and Na+/K+-ATPase Activity in the Hippocampus and Olfactory Bulb of Female Adult Rats

The effects of neonatal handling and the absence of ovarian hormones on the olfactory memory related to a palatable food in adulthood were investigated. Oxidative stress parameters and Na+/K+-ATPase activity in the hippocampus and olfactory bulb of adult pre-puberty ovariectomized female rats handled or not in the neonatal period were also evaluated. Litters were non-handled or handled (10 min/day, days 1-10 after birth). Females from each litter were divided into: OVX (subjected to ovariectomy), sham, and intact. When adults, olfactory memory related to a palatable food (chocolate) was evaluate using the hole-board olfactory task. Additionally, oxidative stress parameters and Na+/K+-ATPase activity were measured in the hippocampus and olfactory bulb. No difference between groups was observed considering olfactory memory evaluation. Neonatal handled rats presented an increase in Na+/K+-ATPase activity in the hippocampus and in the olfactory bulb, compared to non-handled ones. Considering the surgical procedure, there was a decrease in Na+/K+-ATPase and catalase activities in sham and OVX groups, compared to intact animals in the olfactory bulb. We concluded that olfactory memory related to a palatable food in adulthood was not affected by neonatal handling or by pre-puberty surgery, with or without removal of ovaries. The difference observed between groups in catalase and Na+/K+-ATPase activity does not seem to be related to the olfactory memory. Additionally, the increase in Na+/K+-ATPase activity (an enzyme that maintains the neurochemical gradient necessary for neuronal excitability) induced by neonatal handling may be related to neuroplastic changes in the hippocampus and olfactory bulb.     

Effects of ovariectomy and 17-β estradiol replacement on rat brown adipose tissue mitochondrial function

Taking into account the sexual dimorphism previously reported regarding mitochondrial function and biogenesis in brown adipose tissue, the aim of the present study was to go further into these differences by investigating the effect of ovariectomy and 17-β estradiol (E2) replacement on brown adipose tissue mitochondrial function. In this study, fourteen-week-old control female and ovariectomized female Wistar rats were used. Rats were ovariectomized at 5 weeks of age and were treated every 2 days with placebo (OVX group) or E2 (10 μg/kg) (OVX+E2 group) for 4 weeks before sacrifice. We studied the levels of oxidative capacity, antioxidant defence and oxidative damage markers in brown adipose tissue. Moreover, the levels of key elements of mitochondrial biogenesis as well as UCP1 protein levels, as an index of mitochondrial thermogenic capacity, were also determined. In response to ovariectomy, mitochondrial proliferation increased, resulting in less functional mitochondria, since oxidative capacity and antioxidant defences decreased. Although E2 supplementation was able to restore the serum levels of E2 shown by control rats, the treatment reverted the effects of the ovariectomy only in part, and oxidative and antioxidant capacities in OVX+E2 rats did not reach the levels shown by control females. Taking these results into account, we suggest that ovarian hormones are responsible, at least in part, for the sexual dimorphism in BAT mitochondrial function. However, other signals produced by ovary, rather than E2, would play an important role in the control of mitochondrial function in BAT.