Aging and Lateralization of the Rat Brain on a Biochemical Level

It has been suggested that the lateralization of the human brain underlies hemispheric specialization and that it can be observed also on a biochemical level. Biochemical laterality appears to be a basis of volumetric or functional asymmetry but direct relationships among them are still unclear. Moreover, age-related differences between the right and left hemispheres are not well documented in various rat strains. In the current study, biochemical markers sensitive to Alzheimer disease (activities of high-affinity choline uptake and of nitric oxide synthases, expression of 17β-hydroxysteroid dehydrogenase type 10) were estimated in both hemispheres of young and old male Wistar/Long Evans rats. Our experiments indicate (1) differences in some biochemical markers between young Wistar and Long Evans rats (the activities of endothelial nitric oxide synthase are higher in Long Evans and those of citrate synthase in Wistar rats), (2) more similar brain asymmetry of healthy human/young Wistar brains when compared to those of young Long Evans, (3) the decrease in asymmetry of the physiologically left/right lateralized biomarker during aging (the activity of the high-affinity choline uptake decreases more markedly in the left side of old Wistar rats) in accordance with the HAROLD model, (4) the age-related shift to reversed left/right asymmetry of the physiologically right/left lateralized biomarker (the activity of inducible nitric oxide synthase increases especially in the left side of old Long Evans rats), and finally (5) age-related differences in physiologically unlateralized biomarkers between Wistar and Long Evans rats (changes in the activities of neural/endothelial nitric oxide synthases or in expression of 17β-hydroxysteroid dehydrogenase type 10 are more asymmetrical in old Wistar when compared to rather bilateral alterations of old Long Evans animals). It seems that the physiological lateralization of the human or rat brains on a biochemical level and their age-related alterations are dependent on biomarker type/function. By our opinion, it is difficult, perhaps impossible, to make one simple universal model, at least on a biochemical level. Since lateral analyses are of sufficient sensitivity to reveal subtle links, we recommend using Wistar rather than Long Evans rats in modeling of diseases accompanied by alterations in brain asymmetry.     

Association of renal damage and oxidative stress in a rat model of metabolic syndrome. Influence of gender

This study investigated the association between nephropathy and oxidative stress, by measurement of systolic blood pressure, lipid peroxidation, activities of catalase, manganese- and copper-zinc-superoxide dismutase and endothelial nitric oxide synthase expression and concentrations of nitrates/nitrites in kidneys from rats with Metabolic Syndrome. Weaning female or male rats had 30% sucrose to drink for 24 weeks (Metabolic Syndrome). Modulation by sex hormones was investigated by gonadectomy and hormone replacement. In Metabolic Syndrome, Castrated Metabolic Syndrome + Testosterone males and Ovariectomized Metabolic Syndrome females had increased blood pressure, proteinuria and lipid peroxidation. Nitrates/nitrites and activities of catalase, manganese and copper-zinc-superoxide dismutase decreased vs intact Control, Castrated Metabolic Syndrome males, intact Metabolic Syndrome and Ovariectomized Metabolic Syndrome + Estradiol females. The results suggest that sex hormones modulate the activity of superoxide-dismutase, catalase and endothelial nitric oxide-synthase. Ovariectomy decreased the protection against oxidative stress in females; the opposite occurred in castrated males.     

红花黄色素对新生鼠缺氧后一氧化氮合酶表达的影响

目的:观察红花黄色素对缺氧后脑内诱生型一氧化氮合酶(iNOS)、神经原型一氧化氮合酶(nNOS)及内皮型一氧化氮合酶(eNOS)基因表达的影响,探讨红花黄色素抗缺氧脑损伤的作用.方法:采用SD新生鼠缺氧模型,于缺氧前30 min腹腔注射红花黄色素生药7g/kg,缺氧40 min后复氧48 h,提取脑组织总RNA,应用RT-PCR技术检测三种NOS mRNA的表达量.结果:新生鼠缺氧再复氧48 h,脑内iNOS、nNOS基因表达上升(P＜0.05),预先给予红花黄色素能抑制iNOS、nNOS基因的表达(P＜0.05),但eNOS基因表达不受影响.结论:红花黄色素对缺氧脑损伤的保护作用与NOS基因表达有关.     

Role of cardiovascular nitric oxide system in C-type natriuretic peptide effects

The aims were to evaluate the role of cardiovascular nitric oxide (NO)-system in C-type natriuretic peptide (CNP) actions and to investigate receptor types and signaling pathways involved in this interaction. Wistar rats were infused with saline or CNP. Mean arterial pressure (MAP) and nitrites and nitrates (NOx) excretion were determined. NO synthase (NOS) activity and NOS expression (Western blot) were analyzed in atria, ventricle and aorta. CNP decreased MAP and increased NOx excretion. CNP estimulated NOS activity, inducing no changes on cardiac and vascular endothelial NOS expression. NOS activity induced by CNP was abolished by suramin and calmidazoliumand but it is not modified by anantin. CNP would interact with NPR-C receptor coupled via G proteins leading to the activation Ca(2+)-calmodulin dependent endothelial NOS, increasing NO production which would induce the reduction in cardiac myocyte contractility and ANP synthesis and secretion in right atria and the relaxation of vascular smooth muscle.     

Endothelial nitric oxide synthase modulates gastric ulcer healing in rats

Nitric oxide has been shown to be beneficial for gastric ulcer healing. We determined the relative effects of endothelial and inducible nitric oxide synthases on gastric ulcer healing in rats. Ulcers were induced by serosal application of acetic acid. Ulcer severity, angiogenesis, and nitric oxide synthase expression were assessed 3-10 days later. The effects of inhibitors of nitric oxide synthase were also examined. Inducible nitric oxide synthase mRNA was only detected in ulcerated tissue (maximal at day 3), whereas the endothelial isoform mRNA was detected in normal tissue and increased during ulcer healing. Inducible nitric oxide synthase was expressed in inflammatory cells in the ulcer bed, whereas endothelial nitric oxide synthase was found in the vascular endothelium and in some mucosal cells in both normal and ulcerated tissues. Angiogenesis changed in parallel with endothelial nitric oxide synthase expression. N(6)-(iminoethyl)-L-lysine did not affect angiogenesis or ulcer healing, while N(G)-nitro-L-arginine methyl ester significantly reduced both. In conclusion, endothelial nitric oxide synthase, but not the inducible isoform, plays a significant role in gastric ulcer healing.     

Endothelium-derived nitric oxide synthase protein expression in ovine placental arteries

During the third trimester, fetoplacental and uterine blood flows increase dramatically to meet the high metabolic demands of the growing fetus. We hypothesized that the expression of endothelial nitric oxide synthase (eNOS) in fetoplacental artery endothelium and the concentrations of nitric oxide (NO) and cyclic GMP (cGMP) in amniotic fluid (AF) are increased during the third trimester of ovine gestation. Placental arteries and AF were collected from ewes at 110, 120, 130, and 142 days of gestation (n = 24; mean +/- SEM term = 145 +/- 3 days). Expression of eNOS protein was measured in intact and denuded placental arteries and in endothelium-derived protein by Western analysis and confirmed by immunohistochemistry. Concentrations of NO (nitrates plus nitrites) and cGMP were determined in AF. Placental artery eNOS protein expression was localized to the endothelium, where it was markedly greater than in vascular smooth muscle. Placental artery endothelium-derived eNOS expression and AF cGMP concentrations were similar at 110 and 120 days of gestation; however, both peaked at 130 days at levels two- to threefold above baseline (P < 0.05) before returning to baseline at 142 days of pregnancy. The AF NO (nitrates plus nitrites) levels, however, increased progressively between 120 days of gestation and term (P < 0.05). We concluded that endothelium-derived placental artery eNOS levels, AF NO (nitrates plus nitrites), and AF cGMP were markedly increased during the third trimester, thus supporting a role for NO-mediated elevations in cGMP in the control of fetoplacental blood flow.     

Ultrasound induced the formation of nitric oxide and nitrosonium ions in water and aqueous solutions

Nitric oxide, nitrosonium ions, nitrites, and nitrates are formed in water saturated with air under the action of ultrasound. Nitrosonium ions react with water and hydrogen peroxide to form nitrites and nitrates in sonicated solution, correspondingly. Nitric oxide is practically completely released from sonicated water into the atmosphere and reacts with air oxygen, forming NOx compounds. The oxidation of nitric oxide in aqueous medium by hydroxyl radicals and dissolved oxygen is a minor route of the formation of nitrites and nitrates in ultrasonic field.     

Low density lipoprotein inhibits accumulation of nitrites in murine brain endothelial cell cultures.

Endothelial cells produce nitric oxide which is considered to serve as a major source of endothelial derived relaxing factor activity. It has been demonstrated that activation of mouse brain endothelium by TNF-alpha and IFN-gamma led to accumulation of nitrite which is presumably formed by oxidation of nitric oxide. A number of studies suggest that reactive oxygen species produced by cytokine-activated cells are involved in the conversion of nitric oxide to nitrites and nitrates. We investigated whether low density lipoprotein (LDL), acting as a radical scavenger, is able to inhibit nitrite accumulation in mouse brain endothelial cell cultures and in a cell-free system in which sodium nitroprusside was used as a source of nitric oxide. A comparison of these two models indicates the active involvement of LDL in suppressing nitrite accumulation in murine endothelial cultures.     

Production of nitric oxide and self-nitration of proteins during monocyte differentiation to dendritic cells

Nitric oxide (NO) can stimulate dendritic cells to a more activated state. However, nitric oxide and peroxynitrites production by dendritic cells has been usually associated with pathological situations such as autoimmunity or inflammatory diseases. This study was designed to determine if dendritic cells obtained from healthy volunteers produce nitric oxide and peroxynitrites, which results in protein nitration. The expression of arginase II, but not arginase I, isoform was detected in monocytes and dendritic cells. There was higher inducible nitric oxide synthase (iNOS) protein expression and lower arginase activity both in immature and mature dendritic cells, compared to monocytes. This caused nitric oxide production, and maturation of dendritic cells which provoked a significative increase of nitrites and nitrates compared to immature dendritic cells. There was also peroxynitrites synthesis during monocyte differentiation as shown by the nitration of proteins. Immunoblot revealed a pattern of nitrated proteins in cell extracts obtained from monocytes and dendritic cells, however there were bands that appeared only in human dendritic cells, in particular an intense 90 kDa band. Nitric oxide production and nitrotyrosine formation could affect the antigen presentation and modify the immune response.     

Altered Fronto-Temporal Functional Connectivity in Individuals at Ultra-High-Risk of Developing Psychosis

Background

The superior temporal gyrus (STG) is one of the key regions implicated in psychosis, given that abnormalities in this region are associated with an increased risk of conversion from an at-risk mental state to psychosis. However, inconsistent results regarding the functional connectivity strength of the STG have been reported, and the regional heterogeneous characteristics of the STG should be considered.

Methods

To investigate the distinctive functional connection of each subregion in the STG, we parcellated the STG of each hemisphere into three regions: the planum temporale, Heschl’s gyrus, and planum polare. Resting-state functional magnetic resonance imaging was obtained from 22 first-episode psychosis (FEP) patients, 41 individuals at ultra-high-risk for psychosis (UHR), and 47 demographically matched healthy controls.

Results

Significant group differences (in seed-based connectivity) were demonstrated in the left planum temporale and from both the right and left Heschl’s gyrus seeds. From the left planum temporale seed, the FEP and UHR groups exhibited increased connectivity to the bilateral dorsolateral prefrontal cortex. In contrast, the FEP and UHR groups demonstrated decreased connectivity from the bilateral Heschl’s gyrus seeds to the dorsal anterior cingulate cortex. The enhanced connectivity between the left planum temporale and right dorsolateral prefrontal cortex was positively correlated with positive symptom severity in individuals at UHR (r = .34, p = .03).

Conclusions

These findings corroborate the fronto-temporal connectivity disruption hypothesis in schizophrenia by providing evidence supporting the altered fronto-temporal intrinsic functional connection at earlier stages of psychosis. Our data indicate that subregion-specific aberrant fronto-temporal interactions exist in the STG at the early stage of psychosis, thus suggesting that these aberrancies are the neural underpinning of proneness to psychosis.     

一氧化氮合酶的遗传、生理研究进展

一氧化氮具有广泛的生理功能,哺乳动物体内的NO是由NO合酶(NOS)氧化L-精氨酸而合成的,合成后的NO迅速跨膜扩散释放,NO合成失调能介导多种疾病。催化NO生物合成的NOS有三种亚型:神经元型NOS(nNOS)、内皮型NOS(eNOS)和诱导型NOS(iNOS),目前,人的三型NOS已纯化并且已分子克隆成功,对一氧化氮合酶的遗传研究确认了NOS家族的基因结构和染色体定位。     

Effect of dehydration on nitric oxide, corticotropic and vasopressinergic axis in rat

Effect of dehydration on nitric oxide, corticotropic and vasopressinergic axis in rat. The purpose of our work is to study, in the male 'Wistar' rat, the effects of a chronic dehydration, by deprivation of water for three days out of four, during four repeated cycles, on the evolution of certain blood variables, on the activities of both corticotropic and vasopressinergic axis and on the synthesis of nitric oxide. The chronic dehydration causes a considerable reduction of the body weight, an activation of the vasopressinergic axis and an increase in the circulating rates of the nitrates/nitrites, which represent the final metabolites of the reaction of oxidation of nitric oxide. The pituitary-adrenal axis is not statistically affected by the chronic dehydration. This seems to be in favour of a possible adaptation of corticotropic axis to chronic water deprivation. The activation of synthesis of nitric oxide shows its implication in the regulation of the water balance and its buffer effect on vasoconstriction and hypertension induced by water stress.     

Presence and activity of nitric oxide synthase isoforms in ischemia-reperfusion-injured flaps

Nitric oxide is produced from the amino acid L-arginine by nitric oxide synthase, which has three known isoforms: (1) endothelial nitric oxide synthase and (2) brain nitric oxide synthase, both of which are constitutive nitric oxide synthase; and (3) inducible nitric oxide synthase. The authors' hypothesis is that after reperfusion injury, endothelial cell dysfunction leads to disruption of nitric oxide synthase-mediated nitric oxide production and that this may in part explain the deleterious effects of ischemia-reperfusion injury on tissue survival and blood reflow in flaps. An experiment was designed to study the effects of ischemia-reperfusion injury on the bioactivity of all three isoforms of nitric oxide synthase. Buttock skin flaps and latissimus dorsi myocutaneous flaps were elevated in eight pigs. Flaps on one side of the animal were randomized to receive 6 hours of arterial ischemia, whereas flaps on the other side served as controls. At 6 hours of ischemia and at 1, 4, and 18 hours after reflow, tissue biopsy specimens were obtained and were processed for both constitutive nitric oxide synthase and inducible nitric oxide synthase enzyme activity on the basis of the L-citrulline assay. In addition, specimens were processed for Western blot analysis of the three isoforms. The authors' results revealed three key findings: first, there was a statistically significant (p < 0.001) decrease in constitutive nitric oxide synthase activity of ischemia-reperfusion-injured flaps as compared with controls in both skin and muscle for all time intervals measured. Second, Western blot analyses of endothelial nitric oxide synthase and brain nitric oxide synthase showed a significant decrease in the signal intensity in ischemic and reperfused tissue as compared with controls. Third, the inducible nitric oxide synthase isoform's activity and protein remained undetectable in both tissue types for all time points measured. The authors' data demonstrated that following ischemia-reperfusion injury in the pig flap model there was a disruption of constitutive nitric oxide synthase expression and activity, which may lead to decreased nitric oxide production. The significant decrease in nitric oxide synthase activity found in the current study may partly explain the mechanism of tissue damage in flaps subjected to ischemia-reperfusion injury. Knowledge of the kinetics of nitric oxide synthase activity under conditions of ischemia-reperfusion injury has important implications for the choice and timing of delivery of therapeutic agents whose goal is to increase the bioavailability of nitric oxide in reperfused tissue.     

The modulation of neuroinflammation by inducible nitric oxide synthase

The accumulation and propagation of misfolded proteins in the brain is a pathological hallmark shared by many neurodegenerative diseases, such as the depositions of β-amyloid and hyperphosphorylated tau proteins in Alzheimer''s disease. Initial evidence shows the role of nitric oxide synthases in the development of neurodegenerative diseases. A recent, in an exciting paper (Bourgognon et al. in Proc Natl Acad Sci USA 118, 1–11, 2021. 10.1073/pnas.2009579118) it was shown that the inducible nitric oxide synthase plays an important role in promoting oxidative and nitrergic stress leading to neuroinflammation and consequently neuronal function impairments and decline in synaptic strength in mouse prion disease. In this context, we reviewed the possible mechanisms of nitric oxide synthase in the generation of neurodegenerative diseases.     

Detour behavior in the Quokka (Setonix brachyurus)

Four quokkas (Setonix brachyurus) were tested in their natural environment for the ability to progress around a barrier to a desired goal object (food). Symmetrical and asymmetrical barriers were used with different lengths of side arm. Three quokkas showed significant tendencies to progress either left or right around the barrier, though this laterality declined as the length of the side arm of the barrier was extended. One quokka showed no behavioral laterality and this animal was also the only one to show spatial reasoning (spontaneous selection of the shorter route on first presentation of the asymmetrical barrier) as opposed to spatial learning (progressive improvement in choice of the shorter route with repeated experience).     

Perivascular nerve fibres and endothelial cells of the rat basilar artery: immuno-gold labelling of antigenic sites for type I and type III nitric oxide synthase

Ultrastructural localisation of type I (neuronal) and type III (endothelial) isoforms of nitric oxide synthase in perivascular nerve fibres (axons) and endothelial cells was studied in the Wistar rat cerebral basilar artery, using monoclonal antibodies either to type I or type III nitric oxide synthase and post-embedding colloidal-gold immunocytochemistry. Labelling signal (gold particles) for type I and type III nitric oxide synthase was localised both in axons and endothelial cells. In the axon profiles, labelling for either type I or type III nitric oxide synthase was localised in the axoplasm and the lumen and/or membrane of small agranular synaptic vesicles. In the endothelial cells, labelling for either type-I or type-III nitric oxide synthase was predominantly in the cytoplasm. The present qualitative data extends our previous study of cerebrovascular nerve fibres and endothelial cells employing monoclonal antibodies; the localisation of nitric oxide synthase in a subpopulation of synaptic vesicles in nitric oxide synthase-positive cerebrovascular nerves suggests that vesicular mechanisms may be involved in the production/release of nitric oxide. © 1998 Chapman and Hall     

The 27-bp VNTR Polymorphism in Intron 4 of the Human eNOS Gene in Healthy Singaporean Chinese, Indians, and Malays

Human endothelial nitric oxide synthase (eNOS) is one isoform of the nitric oxide synthases that are responsible for nitric oxide synthesis from L-arginine. The gene encoding eNOS contains a 27-bp VNTR polymorphism in intron 4. We report here for the first time the presence of a novel allele 3, which was absent in all other populations studied to date, in 1.7% each of Singaporean Indians and Malays. We also detected the presence of a novel genotype 3/5 in 3.4% each of Singaporean Indians and Malays. Allele 6, which was absent in Han Chinese from northern China and Taiwan and was also absent in Indians from the Indian subcontinent, was found in 2.1% of Singaporean Chinese and in 0.3% of Singaporean Indians.     

Inhibition of compensatory lung growth in endothelial nitric oxide synthase-deficient mice

Pneumonectomy results in rapid compensatory growth of the remaining lung and also leads to increased flow and shear stress, which are known to stimulate endothelial nitric oxide synthase (eNOS). Nitric oxide is an essential mediator of vascular endothelial growth factor-induced angiogenesis, which should necessarily occur during compensatory lung growth. Thus our hypothesis is that eNOS is critical for compensatory lung growth. To test this, left pneumonectomy was performed in eNOS-deficient mice (eNOS-/-), and compensatory growth of the right lung was characterized throughout 14 days postpneumonectomy and compared with wild-type pneumonectomy and sham controls. Compensatory lung growth was severely impaired in eNOS-/- mice, as demonstrated by significant reductions in lung weight index, lung volume index, and volume of respiratory region. Also, pneumonectomy-induced increases in alveolar surface density and cell proliferation were prevented in eNOS-/- mice, indicating that eNOS plays a role in alveolar hyperplasia. Compensatory lung growth was also impaired in wild-type mice treated with the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester. Together, these results indicate that eNOS is critical for compensatory lung growth.     

A comparison of organic and inorganic nitrates/nitrites

Although both organic and inorganic nitrates/nitrites mediate their principal effects via nitric oxide, there are many important differences. Inorganic nitrate and nitrite have simple ionic structures and are produced endogenously and are present in the diet, whereas their organic counterparts are far more complex, and, with the exception of ethyl nitrite, are all medicinally synthesised products. These chemical differences underlie the differences in pharmacokinetic properties allowing for different modalities of administration, particularly of organic nitrates, due to the differences in their bioavailability and metabolic profiles. Whilst the enterosalivary circulation is a key pathway for orally ingested inorganic nitrate, preventing an abrupt effect or toxic levels of nitrite and prolonging the effects, this is not used by organic nitrates. The pharmacodynamic differences are even greater; while organic nitrates have potent acute effects causing vasodilation, inorganic nitrite's effects are more subtle and dependent on certain conditions. However, in chronic use, organic nitrates are considerably limited by the development of tolerance and endothelial dysfunction, whereas inorganic nitrate/nitrite may compensate for diminished endothelial function, and tolerance has not been reported. Also, while inorganic nitrate/nitrite has important cytoprotective effects against ischaemia-reperfusion injury, continuous use of organic nitrates may increase injury. While there are concerns that inorganic nitrate/nitrite may induce carcinogenesis, direct evidence of this in humans is lacking. While organic nitrates may continue to dominate the therapeutic arena, this may well change with the increasing recognition of their limitations, and ongoing discovery of beneficial effects and specific advantages of inorganic nitrate/nitrite.