High plasma aldosterone concentration is a novel risk factor of cognitive impairment in patients with hypertension

Illness perspectives in patients with primary aldosteronism

OBJECTIVE

The burden of symptoms and treatment in patients with primary aldosteronism (PA), as well as the patients' experience of the health care is sparsely studied. The objectives of this study were to describe symptoms considered to be the most troublesome by patients with PA, and to explore health related worries and expectations following treatment.

METHODS

This was an explorative qualitative study where 25 patients with PA, diagnosed between 2017 and 2019, were included; 13 patients who had undergone adrenalectomy and 12 who were receiving medical treatment. Data was collected during six group interviews and analyzed using a thematic approach.

RESULTS

Three main themes were identified: 1) Distress of the past, where the most important issues were struggle to receive a correct diagnosis, impaired well-being and the consumption of a large number of tablets, 2) Satisfaction after receiving a correct diagnosis, both in patients with unilateral and bilateral disease, but also dissatisfaction with lack of information about the disease, and 3) Future concerns, where worries about the long-term effects of PA on health in general dominated.

CONCLUSIONS

Our findings illustrate several important issues related to PA where improvements in patient care are needed, including actions aiming at shortening the long diagnostic delay, a thorough information to the patients about the disease is of great importance, and that all patients with PA, regardless of treatment, would benefit from a structured long-term follow-up.

The new mechanism of cognitive decline induced by hypertension: High homocysteine-mediated aberrant DNA methylation

The prevalence and severity of hypertension-induced cognitive impairment increase with the prolonging of hypertension. The mechanisms of cognitive impairment induced by hypertension primarily include cerebral blood flow perfusion imbalance, white and gray matter injury with blood-brain barrier disruption, neuroinflammation and amyloid-beta deposition, genetic polymorphisms and variants, and instability of blood pressure. High homocysteine (HHcy) is an independent risk factor for hypertension that also increases the risk of developing early cognitive impairment. Homocysteine (Hcy) levels increase in patients with cognitive impairment induced by hypertension. This review summarizes a new mechanism whereby HHcy-mediated aberrant DNA methylation and exacerbate hypertension. It involves changes in Hcy-dependent DNA methylation products, such as methionine adenosyltransferase, DNA methyltransferases, S-adenosylmethionine, S-adenosylhomocysteine, and methylenetetrahydrofolate reductase (MTHFR). The mechanism also involves DNA methylation changes in the genes of hypertension patients, such as brain-derived neurotrophic factor, apolipoprotein E4, and estrogen receptor alpha, which contribute to learning, memory, and attention deficits. Studies have shown that methionine (Met) induces hypertension in mice. Moreover, DNA hypermethylation leads to cognitive behavioral changes alongside oligodendroglial and/or myelin deficits in Met-induced mice. Taken together, these studies demonstrate that DNA methylation regulates cognitive dysfunction in patients with hypertension. A better understanding of the function and mechanism underlying the effect of Hcy-dependent DNA methylation on hypertension-induced cognitive impairment will be valuable for early diagnosis, interventions, and prevention of further cognitive defects induced by hypertension.

Changes in Prevalence and Determinants of Self-Reported Hypertension among Bangladeshi Older Adults during the COVID-19 Pandemic

The present study aimed to assess the changes in the prevalence and determinants of self-reported hypertension among older adults during the COVID-19 pandemic in Bangladesh. This repeated cross-sectional study was conducted on two successive occasions (October 2020 and September 2021), overlapping the first and second waves of the COVID-19 pandemic in Bangladesh. The survey was conducted through telephone interviews among Bangladeshi older adults aged 60 years and above. The prevalence of hypertension was measured by asking a question about whether a doctor or health professional told the participants that they have hypertension or high blood pressure and/or whether they are currently using medication to control it. We also collected information on the socio-economic characteristics of the participants, their cognitive ability, and their COVID-19-related attributes. A total of 2077 older adults with a mean age of 66.7 ± 6.4 years participated in the study. The samples were randomly selected on two successive occasions from a pre-established registry developed by the ARCED Foundation. Thus, the sample in the 2021-survey (round two; n = 1045) was not the same as that in the 2020-survey (round one; n = 1031) but both were drawn from the same population. The findings revealed that the prevalence of hypertension significantly increased across the two periods (43.7% versus 56.3%; p = 0.006). The odds of hypertension were 1.34 times more likely in round two than in the round one cohort (AOR 1.34, 95% CI 1.06-1.70). We also found that having formal schooling, poorer memory or concentration, and having had received COVID-19 information were all associated with an increased risk of hypertension in both rounds (p < 0.05). The findings of the present study suggest providing immediate support to ensure proper screening, control, and treatment of hypertension among older adults in Bangladesh.

Explore the correlation between cerebral vessel characteristics with cognitive impairment among elder individuals: a community study from China

Background

Brain Magnetic Resonance Imaging (MRI) examination of cerebral small vessel disease (CSVD) may help screen vascular cognitive impairment. A recently estimated CSVD score system was suggested to capture the overall CSVD burden. The study aimed to detect the association between systemic evaluation score of cerebral vascular imaging parameters with cognitive functions.

Methods

This was a cross-sectional study in community settings. From October 2017 to September 2018, elder (≧60) residents were recruited through on-site visit in 6 communities from Shanghai, China. The participants underwent brain MRI, carotid ultrasound, laboratory tests of blood and urine samples. Cognitive function was evaluated using Mini-Mental State Examination (MMSE). MRI score of CSVD was calculated according to the 2012 standard for the evaluation of statistical changes in imaging.

Results

Total 171 subjects completed survey and examinations. There were 55 participants diagnosed with cognitive impairment, with a total percentage of 32.2%. Participants with and without cognitive impairment showed significant differences in age, BMI and education level. Cognitive impaired participant had more disease history/comorbidity of hypertension and chronic renal insufficiency, higher level of creatinine, as well as lower level of full blood count (FBC) and alanine aminotransferase (ALT). A significant difference was detected in CSVD score between participants with and without cognitive impairment. Results of linear regression analysis showed significant negative correlations between MMSE score and both left and right carotid artery peak systolic velocity (PSV), however the CSVD score was only borderline (P = 0.0566) positively correlated with MMSE. Multivariate linear correlation analysis including all collected risk factor data showed that left carotid artery PSV score was among the independent negative correlated factors of MMSE. Multivariate binary logistic analysis showed that age, education and history of hypertension were the only statistically associated factors of cognitive impairment.

Conclusions

The current study identified high prevalence of cognitive impairment in a Chinese community. In addition, correlations between cerebral vascular disease imaging status and cognitive functions were confirmed although the sample size limited the possibility of screening cognitive impairment with imaging technique.

Neuroprotective Biomarkers and Cognitive Function in a Long-Term Prospective Population-based Study of Aging US Adults

BACKGROUND

Relationships between brain-derived neurotrophic factor (BDNF), insulin-like growth factor (IGF-1), aldosterone, and cognition in aging were evaluated in the population-based Epidemiology of Hearing Loss Study (1993 to present).

METHODS

Beginning in 1998 to 2000, cognitive impairment was assessed by report of physician diagnoses and the Mini-Mental State Examination. In 2009 to 2010 and 2013 to 2016, information was collected on diagnosis of mild cognitive impairment/dementia. Decline in cognitive function was assessed by principal component analysis from additional tests administered during 2009 to 2010 and 2013 to 2016. BDNF, IGF-1, and aldosterone were measured in serum collected in 1998 to 2000.

RESULTS

There were 1970 participants (mean age=66.9 y; 59.1% female) without cognitive impairment at baseline. Among women, low BDNF was associated with 16-year incident cognitive impairment [hazard ratio=1.76; 95% confidence interval (CI)=1.04, 2.98]. Among men, increasing IGF-1 was associated with decreased risk [per SD: relative risk (RR)=0.57; 95% CI=0.35, 0.92], whereas increasing aldosterone levels were associated with increased risk (per SD: RR=1.28; 95% CI=1.01, 1.62) for 5-year incident mild cognitive impairment/dementia. Overall, low BDNF was associated with increased risk (RR=1.52; 95% CI=1.02, 2.26) for 5-year cognitive decline.

CONCLUSION

Low levels of serum BDNF and IGF-1 were associated with poorer cognition during aging. There may be differential biomarker effects by sex.

Quantitative Trait Module-Based Genetic Analysis of Alzheimer's Disease

The pathological features of Alzheimer's Disease (AD) first appear in the medial temporal lobe and then in other brain structures with the development of the disease. In this work, we investigated the association between genetic loci and subcortical structure volumes of AD on 393 samples in the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort. Brain subcortical structures were clustered into modules using Pearson's correlation coefficient of volumes across all samples. Module volumes were used as quantitative traits to identify not only the main effect loci but also the interactive effect loci for each module. Thirty-five subcortical structures were clustered into five modules, each corresponding to a particular brain structure/area, including the limbic system (module I), the corpus callosum (module II), thalamus-cerebellum-brainstem-pallidum (module III), the basal ganglia neostriatum (module IV), and the ventricular system (module V). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment results indicate that the gene annotations of the five modules were distinct, with few overlaps between different modules. We identified several main effect loci and interactive effect loci for each module. All these loci are related to the function of module structures and basic biological processes such as material transport and signal transduction.

Effects of chronically high levels of aldosterone on different cognitive dimensions: an investigation in patients with primary aldosteronism

Primary aldosteronism is a natural model for chronic aldosterone excess in humans and associated with symptoms of anxiety and depression. Cognitive deficits are inherent to the symptomatology of depression and anxiety disorders. Mineralocorticoid receptors and aldosterone appear to play a role in memory. Aldosterone was additionally supposed to be a risk factor for cognitive decline in patients with essential hypertension. The objective of this study was to investigate possible effects of chronically high aldosterone concentrations on cognitive function. A range of cognitive dimensions were assessed in 19 patients (9 males, 10 females); mean age 47.1 (12.5) under standardized treatment and several rating scales for anxiety, depression, quality of life and sleep were administered. Cognitive parameters were compared to standard norms from a large, healthy standardization sample. Patients showed increased levels of anxiety and depression without meeting diagnostic criteria for a disorder. Besides a numerically lower attention score, patients did not show any significant differences in the cognitive dimensions. Anxiety and depression were negatively correlated with quantitative performance in males. In females, a negative correlation between sleep disturbances and abstract reasoning and a positive correlation with quantitative performance were found. Our data showed no specific effect of chronic aldosterone in the tested cognitive parameters overall at least in younger patients, but they indicate sexually dimorphic regulation processes.

Synergism of antihypertensives and cholinesterase inhibitors in Alzheimer's disease

INTRODUCTION

We investigated the effect of antihypertensive (aHTN) medications and cholinesterase inhibitors (ChEIs) on the cognitive decline in patients with Alzheimer's disease (AD) and analyzed synergism by chemogenomics systems pharmacology mapping.

METHODS

We compared the effect of aHTN drugs on Mini-Mental State Examination scores in 617 AD patients with hypertension, and studied the synergistic effects.

RESULTS

The combination of diuretics, calcium channel blockers, and renin-angiotensin-aldosterone system blockers showed slower cognitive decline compared with other aHTN groups (Δβ = +1.46, P < .0001). aHTN medications slow down cognitive decline in ChEI users (Δβ = +0.56, P = .006), but not in non-ChEI users (Δβ = -0.31, P = .53).

DISCUSSION

aHTN and ChEI drugs showed synergistic effects. A combination of diuretics, renin-angiotensin-aldosterone system blockers, and calcium channel blockers had the slowest cognitive decline. The chemogenomics systems pharmacology-identified molecular targets provide system pharmacology interpretation of the synergism of the drugs in clinics. The results suggest that improving vascular health is essential for AD treatment and provide a novel direction for AD drug development.

Enteric Microbiota⁻Gut⁻Brain Axis from the Perspective of Nuclear Receptors

Nuclear receptors (NRs) play a key role in regulating virtually all body functions, thus maintaining a healthy operating body with all its complex systems. Recently, gut microbiota emerged as major factor contributing to the health of the whole organism. Enteric bacteria have multiple ways to influence their host and several of them involve communication with the brain. Mounting evidence of cooperation between gut flora and NRs is already available. However, the full potential of the microbiota interconnection with NRs remains to be uncovered. Herewith, we present the current state of knowledge on the multifaceted roles of NRs in the enteric microbiota–gut–brain axis.

Mineralocorticoid receptor antagonism prevents obesity-induced cerebral artery remodeling and reduces white matter injury in rats

OBJECTIVE

Midlife obesity is a risk factor for dementia development. Obesity has also been linked to hyperaldosteronism, and this can be modeled in rats by high fat (HF) feeding from weaning. Aldosterone, or activation of the mineralocorticoid receptor (MR) causes cerebrovascular injury in lean hypertensive rats. We hypothesized that rats fed a HF diet would show inward middle cerebral artery (MCA) remodeling that could be prevented by MR antagonism. We further proposed that the cerebral artery remodeling would be associated with white mater injury.

METHODS

Three-week-old male Sprague-Dawley rats were fed a HF diet ± the MR antagonist canrenoic acid (Canr) for 17 weeks. Control rats received normal chow (control NC). MCA structure was assessed by pressure myography.

RESULTS

The MCAs from HF fed rats had smaller lumens and thicker walls when compared to arteries from control NC rats; Canr prevented the MCA remodeling associated with HF feeding. HF feeding increased the mRNA expression of markers of cell proliferation and vascular inflammation in cerebral arteries and Canr treatment prevented this. White mater injury was increased in the rats fed the HF diet and this was reduced by Canr treatment. The expression of doublecortin, a marker of new and immature neurons was reduced in HF fed rats, and MR antagonism normalized this.

CONCLUSIONS

These data suggest that HF feeding leads to MR dependent remodeling of the MCA and this is associated with markers of dementia development.

Reprint of: Contrasting effects of vortioxetine and paroxetine on pineal gland biochemistry in a tryptophan-depletion model of depression in female rats

We studied the effects of the multi-modal antidepressant, vortioxetine and the SSRI, paroxetine on pineal melatonin and monoamine synthesis in a sub-chronic tryptophan (TRP) depletion model of depression based on a low TRP diet. Female Sprague-Dawley rats were randomised to groups a) control, b) low TRP diet, c) low TRP diet+paroxetine and d) low TRP diet+vortioxetine. Vortioxetine was administered via the diet (0.76mg/kg of food weight) and paroxetine via drinking water (10mg/kg/day) for 14days. Both drugs resulted in SERT occupancies >90%. Vortioxetine significantly reversed TRP depletion-induced reductions of pineal melatonin and serotonin (5-HT) and significantly increased pineal noradrenaline NA. Paroxetine did none of these things. Other studies suggest pineal melatonin synthesis may involve N-methyl-d-aspartate (NMDA) receptors and glutamatergic modulation. Here observed changes may be mediated via vortioxetine's strong 5-HT reuptake blocking action together with possible additional effects on glutamate neurotransmission in the pineal via NMDA receptor-modulation and possibly with added impetus from increased NA output.

The association between macronutrient intake and cognition in individuals aged under 65 in China: a cross-sectional study

OBJECTIVE

The aim of this retrospective study was to explore the correlation between daily energy intake from macronutrients and cognitive functions in a Chinese population aged less than 65 years.

DESIGN

This is a cross-sectional study to explore the relationships between macronutrients' intake and cognitive function. The analysis of variance (ANOVA) and χ² test were used to compare the demographic and physical characteristics, lifestyle and laboratory parameters with the intake of macronutrients among different quartiles of % fat/energy. Multivariate logistic regression analysis was applied to identify the potential risk factors of mild cognitive impairment (MCI).

PARTICIPANTS

Young and middle-aged participants (age <65 years) were recruited from Beijing, China. The Montreal cognitive assessment (MoCA) and mini-mental state examination (MMSE) were used to evaluate the cognitive functions, and the dietary intake of the participants was estimated with a semi-quantitative food frequency questionnaire (FFQ).

RESULTS

Among the 661 participants, 80 (12.1%) had MCI, while 581 (87.9%) had normal cognitive functions. On evaluating the data based on the age group, educational background, and conditions of hyperlipidaemia and total energy intake, the results revealed that high % fat (upper quartile: adjusted OR (aOR) 3.90, 95% CI1.53 to 9.89, P=0.004), and high % protein intake (upper quartile: aOR 2.77, 95% CI 1.24 to 6.15) were greatly associated with increased frequency of MCI, while high % carbohydrate intake (upper quartile: aOR0.30, 95% CI 0.12 to 0.72) was correlated with decreased prevalence of MCI.

CONCLUSION

The dietary pattern with high percentage of energy intake from fat and protein, and low-energy intake from carbohydrate might have been associated with cognitive decline in a Chinese population under 65 years of age.

Contrasting effects of vortioxetine and paroxetine on pineal gland biochemistry in a tryptophan-depletion model of depression in female rats

We studied the effects of the multi-modal antidepressant, vortioxetine and the SSRI, paroxetine on pineal melatonin and monoamine synthesis in a sub-chronic tryptophan (TRP) depletion model of depression based on a low TRP diet. Female Sprague-Dawley rats were randomised to groups a) control, b) low TRP diet, c) low TRP diet+paroxetine and d) low TRP diet+vortioxetine. Vortioxetine was administered via the diet (0.76mg/kg of food weight) and paroxetine via drinking water (10mg/kg/day) for 14days. Both drugs resulted in SERT occupancies >90%. Vortioxetine significantly reversed TRP depletion-induced reductions of pineal melatonin and serotonin (5-HT) and significantly increased pineal noradrenaline NA. Paroxetine did none of these things. Other studies suggest pineal melatonin synthesis may involve N-methyl-d-aspartate (NMDA) receptors and glutamatergic modulation. Here observed changes may be mediated via vortioxetine's strong 5-HT reuptake blocking action together with possible additional effects on glutamate neurotransmission in the pineal via NMDA receptor-modulation and possibly with added impetus from increased NA output.

A Risk Factor Analysis of Cognitive Impairment in Elderly Patients with Chronic Diseases in a Chinese Population

Background

This study analyzed the risk factors of cognitive impairment (CI) in elderly patients with chronic diseases.

Material/Methods

In total of 385 elderly patients with chronic diseases were selected and assigned into CI and normal groups. The activities of daily living (ADL), global deterioration scale (GDS), Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment Scale (MoCA), patient-generated subjective global assessment (PG-SGA), and mini nutritional assessment (MNA) were performed to analyze the differences between the 2 groups. Logistic regression analysis was conducted for risk factors of CI in elderly patients with chronic diseases.

Results

There were differences in age, education level, type 2 diabetes mellitus, multifocal cerebral infarction, hearing, and eyesight between CI and normal groups. Patients in the CI group showed more CD4⁺ cells, more admission times, and higher GDS scores than the normal group. Also, MMSE and MoCA scores revealed differences in total score, directive force, attention and calculating ability, language, delayed memory, reading comprehension, writing, and visual-spatial ability between the 2 groups. The number of B and CD8⁺ cells, ADL, and MNA scores were protective factors, while cerebral infarction history, number of CD4+ cells, admission times, GDS score, and age were risk factors of CI in elderly patients with chronic diseases.

Conclusions

Our study provides evidence that cerebral infarction history, number of CD4+ cells, admission times, GDS score, and age are risk factors of CI in elderly patients with chronic diseases.

n-3 Polyunsaturated Fatty Acids: Promising Nutrients for Preventing Cardiovascular Disease

The adoption of the Western-style diet, with decreased fish intake and lack of exercise, has increased the prevalence of cardiovascular disease (CVD) in Japan. Statin treatment has been established to reduce the risk of cardiovascular events; however, 60%–70% of these events occur despite its use. Thus, the residual risk for CVD should be identified and resolved to reduce further cardiovascular events. The serum levels of n-3 polyunsaturated fatty acids (PUFAs), including eicosapentaenoic acid and docosahexaenoic acid, are reportedly associated with an increased incidence of cardiovascular events and mortality, whereas the addition of n-3 PUFA treatment to the statin treatment decreases cardiovascular events. Similar to statins, n-3 PUFAs have pleiotropic effects in addition to lipid-modifying effects. Pre-clinical and clinical studies have shown that n-3 PUFAs prevent cardiovascular events by ameliorating endothelial function and attenuating lipid accumulation, vascular inflammation, and macrophage recruitment, thereby causing coronary plaque development and rupture. Taken together, n-3 PUFAs are comprehensively able to attenuate the atherogenic response. Therefore, n-3 PUFA intake is recommended to prevent cardiovascular events, particularly in patients with multiple cardiovascular risk factors.

Evaluating the relationship of blood pressure, plasma angiotensin peptides and aldosterone with cognitive functions in patients with hypertension

Renin Angiotensin Aldosterone System (RAAS) plays an important role in the development of hypertension. On the other hand, hypertension is a well-known and independent risk factor for cognitive impairment. The aim of the present study was to evaluate the relationship of blood pressure control, plasma angiotensin peptides and aldosterone with cognitive functions. Forty-one patients who were under treatment with the same antihypertensive medications for at least three months were included in the study. Plasma angiotensin II, angiotensin 1-7, angiotensin IV, and aldosterone concentrations were analyzed using an enzyme-linked immunosorbent assay (ELISA). Standardized Mini Mental State Examination (SMMSE) was used to evaluate cognitive functions. When the participants were grouped according to their SMMSE scores (cut-off value: 26 points), we determined significant differences between systolic blood pressure (SBP) levels, diastolic blood pressure levels, plasma angiotensin II and angiotensin 1-7 concentrations of the groups. When the participants were stratified according to their SBP levels (cut-off value: 140 mm Hg), we found significant differences in SMMSE scores and plasma angiotensin IV concentrations of the groups. A negative correlation between SBP and SMMSE scores and strong linear correlations among angiotensin peptides levels were determined. The relationship found between SBP and SMMSE in the present study was compatible with the literature. Our 33 patients were using at least one angiotensin II receptor blocker (ARB). Regarding AT1 receptor blockage, the significant association between higher SMMSE scores and increased angiotensin peptides may support a finding that ARBs prevent dementia and improve cognitive function. Further larger studies are needed to confirm and prove the relation of RAAS biochemical parameters with cognitive function.

Hypertension and cognitive dysfunction in elderly: blood pressure management for this global burden

Arterial hypertension and stroke are strong independent risk factors for the development of cognitive impairment and dementia. Persistently elevated blood pressure (BP) is known to impair cognitive function, however onset of new cognitive decline is common following a large and multiple mini strokes. Among various forms of dementia the most prevalent include Alzheimer’s disease (AD) and vascular dementia (VaD) which often present with similar clinical symptoms and challenging diagnosis. While hypertension is the most important modifiable vascular risk factor with antihypertensive therapy reducing the risk of stroke and potentially slowing cognitive decline, optimal BP levels for maintaining an ideal age-related mental performance are yet to be established. Cognition has improved following the use of at least one representative agent of the major drug classes with further neuroprotection with renin angiotensin inhibitors and calcium channel blockers in the hypertensive elderly. However, a reduction in BP may worsen cerebral perfusion causing an increased risk of CV complications due to the J-curve phenomenon. Given the uncertainties and conflicting results from randomized trials regarding the hypertension management in the elderly, particularly octogenarians, antihypertensive approaches are primarily based on expert opinion. Herein, we summarize available data linking arterial hypertension to cognitive decline and antihypertensive approach with potential benefits in improving cognitive function in elderly hypertensive patients.

Antihypertensive Therapies and Cognitive Function: a Review

Increasing life expectancy has made old age-related health problems like dementia and cognitive decline more prevalent, and these are rapidly becoming important causes of disability and poor quality of life, causing significant add-ons to health-care costs worldwide. Hypertension is the most important modifiable vascular risk factor for the development and progression of both cognitive decline and dementia. In many observational and randomized studies, antihypertensive therapies have been shown to be beneficial in slowing cognitive decline. However, due to observed discrepancies by these studies, there is a lack of consensus on the best antihypertensive strategy for the prevention or slowing of cognitive decline. It is also not clear whether the beneficial effect of antihypertensive therapy is due to the use of a specific class of agents or combination therapy. Thus, we present a comprehensive review of overall antihypertensive therapies and cognition and of the individual antihypertensive therapy classes with their specific protective mechanisms and available clinical evidence behind their effect on cognitive function.

Phosphodiesterase-4 inhibitors ameliorates cognitive deficits in deoxycorticosterone acetate induced hypertensive rats via cAMP/CREB signaling system

Phosphodiesterase-4 (PDE-4) inhibitors promote memory by blocking the degradation of cAMP. Existing evidence also shows that neuronal survival and plasticity are dependent on the phosphorylation of cAMP-response element-binding protein. In this regard, PDE-4 inhibitors have also been shown to reverse pharmacologically and genetically induced memory impairment in animal models. In the present study, the authors examined the effect of both rolipram and roflumilast (PDE-4 inhibitors) on the impairment of learning and memory observed in hypertensive rats. Deoxycorticosterone acetate (DOCA) salt hypertensive model was used to induce learning and memory deficits. The mRNA expression of different PDE-4 subtypes along with the protein levels of pCREB and BDNF in the hippocampus was quantified. Systolic blood pressure was significantly increased in DOCA salt hypertensive rats when compared to sham operated rats. This effect was reversed by clonidine, an α2 receptor agonist, while PDE-4 inhibitors did not. PDE-4 inhibitors significantly improved the time-induced memory deficits in object recognition task (ORT). In DOCA salt hypertensive rats, the gene expression of PDE-4B and PDE-4D was significantly increased. Furthermore, both pCREB and BDNF showed decreased levels of expression in hypertensive rats in comparison to sham operated rats. Repeated administration of PDE-4 inhibitors significantly decreased both PDE-4B and PDE-4D with an increase in the expression of pCREB and BDNF in hypersensitive rats. Also, rolipram, roflumilast and roflumilast N-oxide showed a linear increase in the plasma and brain concentrations after ORT. Our present findings suggested that PDE-4 inhibitors ameliorate hypertension-induced learning impairment via cAMP/CREB signaling that regulates BDNF expression downstream in the rat hippocampus.

Effect of mineralocorticoid receptor blockade on hippocampal-dependent memory in adults with obesity

OBJECTIVE

The hippocampus is crucial for paired-associate learning. Obesity is associated with increased mineralocorticoid receptor (MR) activity in peripheral and possibly central tissues, decreased hippocampal size in humans, and impaired hippocampal learning in rodents. The MR is expressed in hippocampal neurons, and MR blockade improves hippocampal learning in obese animals. The goal of the study was to determine whether MR blockade would modulate paired-associate learning in men and women with obesity.

METHODS

Men and women ages 20-61 years with BMI between 30-45 kg/m(2) were randomly assigned to placebo (n = 11; 7 women) or 50 mg spironolactone daily (n = 12; 7 women) for six weeks. At baseline and post-treatment, subjects underwent a clinical and hormonal evaluation. They also underwent a computerized task that assesses paired-associate learning and has been shown by functional magnetic resonance imaging to activate the hippocampus.

RESULTS

In an ANCOVA model that adjusted for baseline paired-associate learning, age, and race, spironolactone treatment was associated with a significant (P = 0.043) improvement in hippocampal memory as compared to placebo treatment.

CONCLUSIONS

Our findings demonstrate, for the first time, that blocking MR with chronic, low-dose spironolactone treatment improves paired-associate learning in individuals with obesity, suggesting that MR activation contributes to hippocampal memory modulation in humans.

BioAge: toward a multi-determined, mechanistic account of cognitive aging

The search for reliable early indicators of age-related cognitive decline represents a critical avenue for progress in aging research. Chronological age is a commonly used developmental index; however, it offers little insight into the mechanisms underlying cognitive decline. In contrast, biological age (BioAge), reflecting the vitality of essential biological systems, represents a promising operationalization of developmental time. Current BioAge models have successfully predicted age-related cognitive deficits. Research on aging-related cognitive function indicates that the interaction of multiple risk and protective factors across the human lifespan confers individual risk for late-life cognitive decline, implicating a multi-causal explanation. In this review, we explore current BioAge models, describe three broad yet pathologically relevant biological processes linked to cognitive decline, and propose a novel operationalization of BioAge accounting for both moderating and causal mechanisms of cognitive decline and dementia. We argue that a multivariate and mechanistic BioAge approach will lead to a greater understanding of disease pathology as well as more accurate prediction and early identification of late-life cognitive decline.

Interfering with mineralocorticoid receptor activation: the past, present, and future

Aldosterone is a potent mineralocorticoid produced by the adrenal gland. Aldosterone binds to and activates the mineralocorticoid receptor (MR) in a plethora of tissues, but the cardiovascular actions of aldosterone are of primary interest clinically. Although MR antagonists were developed as antihypertensive agents, they are now considered to be important therapeutic options for patients with heart failure. Specifically, blocking only the MR has proven to be a difficult task because of its similarity to other steroid receptors, including the androgen and progesterone receptors. This lack of specificity caused the use of the first-generation mineralocorticoid receptor antagonists to be fraught with difficulty because of the side effects produced by drug administration. However, in recent years, several advances have been made that could potentially increase the clinical use of agents that inhibit the actions of aldosterone. These will be discussed here along with some examples of the beneficial effects of these new therapeutic agents.

The multifaceted mineralocorticoid receptor

The primary adrenal cortical steroid hormones, aldosterone, and the glucocorticoids cortisol and corticosterone, act through the structurally similar mineralocorticoid (MR) and glucocorticoid receptors (GRs). Aldosterone is crucial for fluid, electrolyte, and hemodynamic homeostasis and tissue repair; the significantly more abundant glucocorticoids are indispensable for energy homeostasis, appropriate responses to stress, and limiting inflammation. Steroid receptors initiate gene transcription for proteins that effect their actions as well as rapid non-genomic effects through classical cell signaling pathways. GR and MR are expressed in many tissues types, often in the same cells, where they interact at molecular and functional levels, at times in synergy, others in opposition. Thus the appropriate balance of MR and GR activation is crucial for homeostasis. MR has the same binding affinity for aldosterone, cortisol, and corticosterone. Glucocorticoids activate MR in most tissues at basal levels and GR at stress levels. Inactivation of cortisol and corticosterone by 11β-HSD2 allows aldosterone to activate MR within aldosterone target cells and limits activation of the GR. Under most conditions, 11β-HSD1 acts as a reductase and activates cortisol/corticosterone, amplifying circulating levels. 11β-HSD1 and MR antagonists mitigate inappropriate activation of MR under conditions of oxidative stress that contributes to the pathophysiology of the cardiometabolic syndrome; however, MR antagonists decrease normal MR/GR functional interactions, a particular concern for neurons mediating cognition, memory, and affect.

Aldosterone affects blood flow and vascular tone regulated by endothelium-derived NO: therapeutic implications

Aldosterone, in doses inappropriate to the salt status, plays an important role in the development of cardiovascular injury, including endothelial dysfunction, independent of its hypertensive effects. Acute non-genomic effects of aldosterone acting on mineralocorticoid receptors are inconsistent in healthy humans: vasoconstriction or forearm blood flow decrease via endothelial dysfunction, vasodilatation mediated by increased NO actions, or no effects. However, in studies with experimental animals, aldosterone mostly enhances vasodilatation mediated by endothelium-derived NO. Chronic exposure to aldosterone, which induces genomic responses, results in impairments of endothelial function through decreased NO synthesis and action in healthy individuals, experimental animals and isolated endothelial cells. Chronic aldosterone reduces NO release from isolated human endothelial cells only when extracellular sodium is raised. Oxidative stress is involved in the impairment of endothelial function by promoting NO degradation. Aldosterone liberates endothelin-1 (ET-1) from endothelial cells, which elicits ET(A) receptor-mediated vasoconstriction by inhibiting endothelial NO synthesis and action and through its own direct vasoconstrictor action. Ca(2+) flux through T-type Ca(2+) channels activates aldosterone synthesis and thus enhances unwanted effects of aldosterone on the endothelium. Mineralocorticoid receptor inhibitors, ET(A) receptor antagonists and T-type Ca(2) + channel blockers appear to diminish the pathophysiological participation of aldosterone in cardiovascular disease and exert beneficial actions on bioavailability of endothelium-derived NO, particularly in resistant hypertension and aldosteronism.

The ubiquitous mineralocorticoid receptor: clinical implications

Mineralocorticoid receptors (MR) exist in many tissues, in which they mediate diverse functions crucial to normal physiology, including tissue repair and electrolyte and fluid homeostasis. However, inappropriate activation of MR within these tissues, and especially in the brain, causes hypertension and pathological vascular, cardiac, and renal remodeling. MR binds aldosterone, cortisol and corticosterone with equal affinity. In aldosterone-target cells, co-expression with the 11β-hydroxysteroid dehydrogenase 2 (HSD2) allows aldosterone specifically to activate MR. Aldosterone levels are excessive in primary aldosteronism, but in conditions with increased oxidative stress, like CHF, obesity and diabetes, MR may also be inappropriately activated by glucocorticoids. Unlike thiazide diuretics, MR antagonists are diuretics that do not cause insulin resistance. Addition of MR antagonists to standard treatment for hypertension and cardiac or renal disease decreases end-organ pathology and sympathetic nerve activation (SNA), and increases quality of life indices.

Roles of aldosterone and oxytocin in abnormalities caused by sevoflurane anesthesia in neonatal rats

BACKGROUND

The authors sought to determine whether subjects with pathophysiological conditions that are characterized by increased concentrations of aldosterone have increased susceptibility to the side effects of neonatal anesthesia with sevoflurane.

METHODS

Postnatal day 4-20 (P4-P20) rats were exposed to sevoflurane, 6% and 2.1%, for 3 min and 60-360 min, respectively. Exogenous aldosterone was administered to imitate pathophysiological conditions with increased concentrations of aldosterone.

RESULTS

Six hours of anesthesia with sevoflurane on P4-P5 rats resulted in a more than 30-fold increase in serum concentrations of aldosterone (7.02 ± 1.61 ng/dl vs. 263.75 ± 22.31 ng/dl, mean ± SE, n = 5-6) and reduced prepulse inhibition of the acoustic startle response (F(2,37) = 5.66, P < 0.001). Administration of exogenous aldosterone during anesthesia with sevoflurane enhanced seizure-like electroencephalogram patterns in neonatal rats (48.25 ± 15.91 s vs. 222.00 ± 53.87 s, mean ± SE, n = 4) but did not affect electroencephalographic activity in older rats. Exogenous aldosterone increased activation of caspase-3 (F(3,28) = 11.02, P < 0.001) and disruption of prepulse inhibition of startle (F(3,46) = 6.36; P = 0.001) caused by sevoflurane. Intracerebral administration of oxytocin receptor agonists resulted in depressed seizure-like electroencephalogram patterns (F(2,17) = 6.37, P = 0.009), reduced activation of caspase-3 (t(11) = 2.83, P = 0.016), and disruption of prepulse inhibition of startle (t(7) = -2.9; P = 0.023) caused by sevoflurane.

CONCLUSIONS

These results suggest that adverse developmental effects of neonatal anesthesia with sevoflurane may involve both central and peripheral actions of the anesthetic. Subjects with increased concentrations of aldosterone may be more vulnerable, whereas intracerebral oxytocin receptor agonists may be neuroprotective.

Central regulation of blood pressure by the mineralocorticoid receptor

Addition of mineralocorticoid receptor (MR) antagonists to standard therapy for heart failure, kidney disease, metabolic syndrome, and diabetes is increasing steadily in response to clinical trials demonstrating clear benefits. In addition to blocking deleterious activity of MR within the heart, vessels and kidneys, MR antagonists target MR in hemodynamic regulatory centers in the brain, thereby decreasing excessive sympathetic nervous system drive, vasopressin release, abnormal baroreceptor function, and circulating and tissue pro-inflammatory cytokines. However, brain MR are also involved with cognition, memory, affect and functions yet to be determined. Understanding specific central mechanisms involved in blood pressure regulation by MR is necessary for the development of agents to target downstream events specific to central hemodynamic regulation, not only to avoid the hypokalemia caused by inhibition of renal tubular MR, but also to avoid untoward long term effects of inhibiting brain MR that are not involved in blood pressure control.

What is the role of aldosterone excess in resistant hypertension and how should it be investigated and treated?

Resistant hypertension has evolved as an important global health care problem. Primary aldosteronism is one of several potentially reversible causes of resistant hypertension. Primary aldosteronism can be effectively treated, when recognized, with a mineralocorticoid receptor antagonist, such as spironolactone and eplerenone. Each of these compounds can reduce blood pressure as monotherapy or when given with a range of other antihypertensive drug classes. These compounds have distinctive pharmacokinetic and pharmacodynamic patterns that require some forethought in their use before they are prescribed. However, as the use of mineralocorticoid-blocking agents has gradually increased, the hazards inherent to use of such drugs has become more apparent. Whereas the endocrine side effects of spironolactone are in most cases little more than a cosmetic annoyance, the potassium-sparing effects of both spironolactone and eplerenone can prove fatal if sufficient degrees of hyperkalemia develop. However, for most patients the risk of developing hyperkalemia in and of itself should not discourage the prudent clinician from bringing these compounds into play. Hyperkalemia should always be considered as a likelihood in any patient receiving one or the other of these medications. As such, steps should be taken to lessen the likelihood of it occurring if therapy is being contemplated with agents in this class.

Improvement of cognitive impairment in female type 2 diabetes mellitus mice by spironolactone

Patients with type 2 diabetes mellitus (T2DM) exhibit more severe cognitive decline in females compared with males; however, the preventive approach to this gender-specific cognitive decline is still an enigma. Spironolactone is a potassium-sparing diuretic that also acts as an androgen receptor antagonist. Here, we investigated whether spironolactone attenuates cognitive impairment observed in female T2DM mice. Adult wild-type (WT) mice and an obese T2DM model, KKAy mice, were employed in this study. Cognitive function was evaluated by the shuttle avoidance test and Morris water maze test. Administration of spironolactone (50 mg/kg per day in chow) had no significant effect on blood pressure, glucose tolerance or insulin resistance. In WT mice, no significant sex difference in cognitive function was observed; however, treatment with spironolactone improved spatial memory in the water maze, especially in female WT mice. Administration of spironolactone markedly improved the cognitive decline in female KKAy mice up to the level in male KKAy mice. Spironolactone treatment also improved cognitive function in ovariectomized-KKAy mice, but failed to improve it in those with administration of estradiol (200 µg/kg per day). In diabetic mice, spironolactone improved impaired cognitive function observed in female mice, suggesting that spironolactone may prevent cognitive impairment associated with diabetes in females clinically.

Effect of low-dose (1 mg/day) pitavastatin on left ventricular diastolic function and albuminuria in patients with hyperlipidemia

The aim of the present study was to evaluate the factors that modulate the protective action of statins on cardiorenal function, regardless of the lipid-lowering effect. To treat abnormal serum lipid profiles, low-dose pitavastatin (1.0 mg/day) was administered to 65 hyperlipidemic patients. The exclusion criteria included left ventricular ejection fraction <40% and apparent renal disease. Age- and gender-matched patients with hyperlipidemia (n = 40) served as the controls. After 12 to 16 weeks of pitavastatin treatment, pitavastatin had decreased low-density lipoprotein cholesterol (from 143.5 ± 31.4 to 98.2 ± 19.4 mg/dl, p <0.01), triglycerides (from 157.7 ± 57.2 to 140.5 ± 60.7 mg/dl, p <0.01), E/e' (from 10.8 ± 6.2 to 9.0 ± 4.5, p <0.05), a parameter of left ventricular diastolic function, and albuminuria (from 47.6 ± 55.9 to 28.5 ± 40.0 mg/g creatinine, p <0.01). Furthermore, pitavastatin decreased serum transforming growth factor-β1 (from 709 ± 242 to 550 ± 299 pg/ml, p <0.01), urinary 8-hydroxy-2'-deoxyguanosine (from 6.6 ± 4.1 to 5.0 ± 3.1 μg/g creatinine, p <0.01), an oxidative stress marker, and increased urinary nitrate and nitrite (from 22.5 ± 14.6 to 29.4 ± 27.6 nmol/g creatinine, p <0.05). No such changes were observed in the controls. Multiple regression analysis in the pitavastatin group revealed the effect of pitavastatin on cardiorenal function was associated with suppression of oxidative stress, but not on low-density lipoprotein cholesterol reduction. In conclusion, pitavastatin decreases E/e' and albuminuria, which is associated with suppression of oxidative stress.

Mineralocorticoid receptors in the brain and cardiovascular regulation: minority rule?

A small proportion of brain mineralocorticoid receptors (MR) mediate control of blood pressure, water and electrolyte balance, sodium appetite, and sympathetic drive to the periphery. Circulating inflammatory cytokines modulate MR-mediated changes in sympathoexcitation. Aldosterone binding to MR in the brain occurs, despite concentrations that are 2-3 orders of magnitude less than those of cortisol and corticosterone, which have similar affinity for the MR. The possible mechanisms for selective MR activation by aldosterone, the cellular mechanisms of MR action and the effects of brain MR on hemodynamic homeostasis are considered in this review. MR antagonists are valuable adjuncts to the treatment of chronic cardiovascular and renal disease; the crucial need to discover targets for development of selective therapy for specific MR functions is also discussed.

Local renin-angiotensin system and the brain--a continuous quest for knowledge

The ancient renin-angiotensin system (RAS) was discovered more than a hundred years ago by identifying the rate-limiting enzyme of the system and its relevance to blood pressure regulation. Forty years ago, Detlev Ganten et al. postulated the existence of a tissue RAS. In these forty years, he kept developing the knowledge of these systems either directly or by training or attracting the interest of many researchers. Through the present review, we try to highlight recent advancements that originated from the postulation of local brain RAS. Although a large amount of knowledge accumulated, this system continues to intrigue and stimulate the interest and imagination of many researchers.