A combined analysis of genetically correlated traits identifies 187 loci and a role for neurogenesis and myelination in intelligence.

Intelligence, or general cognitive function, is phenotypically and genetically correlated with many traits, including a wide range of physical, and mental health variables. Education is strongly genetically correlated with intelligence (rg = 0.70). We used these findings as foundations for our use of a novel approach-multi-trait analysis of genome-wide association studies (MTAG; Turley et al. 2017)-to combine two large genome-wide association studies (GWASs) of education and intelligence, increasing statistical power and resulting in the largest GWAS of intelligence yet reported. Our study had four goals: first, to facilitate the discovery of new genetic loci associated with intelligence; second, to add to our understanding of the biology of intelligence differences; third, to examine whether combining genetically correlated traits in this way produces results consistent with the primary phenotype of intelligence; and, finally, to test how well this new meta-analytic data sample on intelligence predicts phenotypic intelligence in an independent sample. By combining datasets using MTAG, our functional sample size increased from 199,242 participants to 248,482. We found 187 independent loci associated with intelligence, implicating 538 genes, using both SNP-based and gene-based GWAS. We found evidence that neurogenesis and myelination-as well as genes expressed in the synapse, and those involved in the regulation of the nervous system-may explain some of the biological differences in intelligence. The results of our combined analysis demonstrated the same pattern of genetic correlations as those from previous GWASs of intelligence, providing support for the meta-analysis of these genetically-related phenotypes.

A Further Comment on 'Large-Scale Cognitive GWAS Meta-Analysis Reveals Tissue-Specific Neural Expression and Potential Nootropic Drug Targets' by Lam et al.

Lam et al. (2018) respond to a commentary of their paper entitled 'Large-Scale Cognitive GWAS Meta-Analysis Reveals Tissue-Specific Neural Expression and Potential Nootropic Drug Targets' Lam et al. (2017). While Lam et al. (2018) have now provided the recommended quality control metrics for their paper, problems remain. Specifically, Lam et al. (2018) do not dispute that the results of their multi-trait analysis of genome-wide association study (MTAG) analysis has produced a phenotype with a genetic correlation of one with three measures of education, but do claim the associations found are specific to the trait of cognitive ability. In this brief paper, it is empirically demonstrated that the phenotype derived by Lam et al. (2017) is more genetically similar to education than cognitive ability. In addition, it is shown that of the genome-wide significant loci identified by Lam et al. (2017) are loci that are associated with education rather than with cognitive ability.

Genetic contributions to self-reported tiredness.

Self-reported tiredness and low energy, often called fatigue, are associated with poorer physical and mental health. Twin studies have indicated that this has a heritability between 6 and 50%. In the UK Biobank sample (N=108 976), we carried out a genome-wide association study (GWAS) of responses to the question, 'Over the last two weeks, how often have you felt tired or had little energy?' Univariate GCTA-GREML found that the proportion of variance explained by all common single-nucleotide polymorphisms for this tiredness question was 8.4% (s.e.=0.6%). GWAS identified one genome-wide significant hit (Affymetrix id 1:64178756_C_T; P=1.36 × 10-11). Linkage disequilibrium score regression and polygenic profile score analyses were used to test for shared genetic aetiology between tiredness and up to 29 physical and mental health traits from GWAS consortia. Significant genetic correlations were identified between tiredness and body mass index (BMI), C-reactive protein, high-density lipoprotein (HDL) cholesterol, forced expiratory volume, grip strength, HbA1c, longevity, obesity, self-rated health, smoking status, triglycerides, type 2 diabetes, waist-hip ratio, attention deficit hyperactivity disorder, bipolar disorder, major depressive disorder, neuroticism, schizophrenia and verbal-numerical reasoning (absolute rg effect sizes between 0.02 and 0.78). Significant associations were identified between tiredness phenotypic scores and polygenic profile scores for BMI, HDL cholesterol, low-density lipoprotein cholesterol, coronary artery disease, C-reactive protein, HbA1c, height, obesity, smoking status, triglycerides, type 2 diabetes, waist-hip ratio, childhood cognitive ability, neuroticism, bipolar disorder, major depressive disorder and schizophrenia (standardised ß's had absolute values<0.03). These results suggest that tiredness is a partly heritable, heterogeneous and complex phenomenon that is phenotypically and genetically associated with affective, cognitive, personality and physiological processes.

Genetic contributions to Trail Making Test performance in UK Biobank.

The Trail Making Test (TMT) is a widely used test of executive function and has been thought to be strongly associated with general cognitive function. We examined the genetic architecture of the TMT and its shared genetic aetiology with other tests of cognitive function in 23 821 participants from UK Biobank. The single-nucleotide polymorphism-based heritability estimates for trail-making measures were 7.9% (part A), 22.4% (part B) and 17.6% (part B-part A). Significant genetic correlations were identified between trail-making measures and verbal-numerical reasoning (rg>0.6), general cognitive function (rg>0.6), processing speed (rg>0.7) and memory (rg>0.3). Polygenic profile analysis indicated considerable shared genetic aetiology between trail making, general cognitive function, processing speed and memory (standardized ß between 0.03 and 0.08). These results suggest that trail making is both phenotypically and genetically strongly associated with general cognitive function and processing speed.

Genetic contributions to self-reported tiredness.

This corrects the article DOI: 10.1038/mp.2017.5.

Association of DPP-4 activity with BMD, body composition, and incident hip fracture: the Cardiovascular Health Study.

There was no association of plasma DPP-4 activity levels with bone mineral density (BMD), body composition, or incident hip fractures in a cohort of elderly community-dwelling adults. INTRODUCTION: Dipeptidyl peptidase IV (DPP-4) inactivates several key hormones including those that stimulate postprandial insulin secretion, and DPP-4 inhibitors (gliptins) are approved to treat diabetes. While DPP-4 is known to modulate osteogenesis, the relationship between DPP-4 activity and skeletal health is uncertain. The purpose of the present study was to examine possible associations between DPP-4 activity in elderly subjects enrolled in the Cardiovascular Health Study (CHS) and BMD, body composition measurements, and incident hip fractures. METHODS: All 1536 male and female CHS participants who had evaluable DXA scans and plasma for DPP-4 activity were included in the analyses. The association between (1) BMD of the total hip, femoral neck, lumbar spine, and total body; (2) body composition measurements (% lean, % fat, and total body mass); and (3) incident hip fractures and plasma levels of DPP-4 activity were determined. RESULTS: Mean plasma levels of DPP-4 activity were significantly higher in blacks (227 ± 78) compared with whites (216 ± 89) (p = 0.04). However, there was no significant association of DPP-4 activity with age or gender (p ≥ 0.14 for both). In multivariable adjusted models, there was no association of plasma DPP-4 activity with BMD overall (p ≥ 0.55 for all) or in gender stratified analyses (p ≥ 0.23). There was also no association of DPP-4 levels and incident hip fractures overall (p ≥ 0.24) or in gender stratified analyses (p ≥ 0.39). CONCLUSION: Plasma DPP-4 activity, within the endogenous physiological range, was significantly associated with race, but not with BMD, body composition, or incident hip fractures in elderly community-dwelling subjects.

Molecular genetic aetiology of general cognitive function is enriched in evolutionarily conserved regions.

Differences in general cognitive function have been shown to be partly heritable and to show genetic correlations with several psychiatric and physical disease states. However, to date, few single-nucleotide polymorphisms (SNPs) have demonstrated genome-wide significance, hampering efforts aimed at determining which genetic variants are most important for cognitive function and which regions drive the genetic associations between cognitive function and disease states. Here, we combine multiple large genome-wide association study (GWAS) data sets, from the CHARGE cognitive consortium (n=53 949) and UK Biobank (n=36 035), to partition the genome into 52 functional annotations and an additional 10 annotations describing tissue-specific histone marks. Using stratified linkage disequilibrium score regression we show that, in two measures of cognitive function, SNPs associated with cognitive function cluster in regions of the genome that are under evolutionary negative selective pressure. These conserved regions contained ~2.6% of the SNPs from each GWAS but accounted for ~40% of the SNP-based heritability. The results suggest that the search for causal variants associated with cognitive function, and those variants that exert a pleiotropic effect between cognitive function and health, will be facilitated by examining these enriched regions.

Genome-wide association study of cognitive functions and educational attainment in UK Biobank (N=112 151).

People's differences in cognitive functions are partly heritable and are associated with important life outcomes. Previous genome-wide association (GWA) studies of cognitive functions have found evidence for polygenic effects yet, to date, there are few replicated genetic associations. Here we use data from the UK Biobank sample to investigate the genetic contributions to variation in tests of three cognitive functions and in educational attainment. GWA analyses were performed for verbal-numerical reasoning (N=36 035), memory (N=112 067), reaction time (N=111 483) and for the attainment of a college or a university degree (N=111 114). We report genome-wide significant single-nucleotide polymorphism (SNP)-based associations in 20 genomic regions, and significant gene-based findings in 46 regions. These include findings in the ATXN2, CYP2DG, APBA1 and CADM2 genes. We report replication of these hits in published GWA studies of cognitive function, educational attainment and childhood intelligence. There is also replication, in UK Biobank, of SNP hits reported previously in GWA studies of educational attainment and cognitive function. GCTA-GREML analyses, using common SNPs (minor allele frequency>0.01), indicated significant SNP-based heritabilities of 31% (s.e.m.=1.8%) for verbal-numerical reasoning, 5% (s.e.m.=0.6%) for memory, 11% (s.e.m.=0.6%) for reaction time and 21% (s.e.m.=0.6%) for educational attainment. Polygenic score analyses indicate that up to 5% of the variance in cognitive test scores can be predicted in an independent cohort. The genomic regions identified include several novel loci, some of which have been associated with intracranial volume, neurodegeneration, Alzheimer's disease and schizophrenia.

Pleiotropy between neuroticism and physical and mental health: findings from 108 038 men and women in UK Biobank.

People with higher levels of neuroticism have an increased risk of several types of mental disorder. Higher neuroticism has also been associated, less consistently, with increased risk of various physical health outcomes. We hypothesised that these associations may, in part, be due to shared genetic influences. We tested for pleiotropy between neuroticism and 17 mental and physical diseases or health traits using linkage disequilibrium regression and polygenic profile scoring. Genetic correlations were derived between neuroticism scores in 108 038 people in the UK Biobank and health-related measures from 14 large genome-wide association studies (GWASs). Summary information for the 17 GWASs was used to create polygenic risk scores for the health-related measures in the UK Biobank participants. Associations between the health-related polygenic scores and neuroticism were examined using regression, adjusting for age, sex, genotyping batch, genotyping array, assessment centre and population stratification. Genetic correlations were identified between neuroticism and anorexia nervosa (rg=0.17), major depressive disorder (rg=0.66) and schizophrenia (rg=0.21). Polygenic risk for several health-related measures were associated with neuroticism, in a positive direction in the case of bipolar disorder, borderline personality, major depressive disorder, negative affect, neuroticism (Genetics of Personality Consortium), schizophrenia, coronary artery disease, and smoking (ß between 0.009-0.043), and in a negative direction in the case of body mass index (ß=-0.0095). A high level of pleiotropy exists between neuroticism and some measures of mental and physical health, particularly major depressive disorder and schizophrenia.

Examining non-syndromic autosomal recessive intellectual disability (NS-ARID) genes for an enriched association with intelligence differences.

Two themes are emerging regarding the molecular genetic aetiology of intelligence. The first is that intelligence is influenced by many variants and those that are tagged by common single nucleotide polymorphisms account for around 30% of the phenotypic variation. The second, in line with other polygenic traits such as height and schizophrenia, is that these variants are not randomly distributed across the genome but cluster in genes that work together. Less clear is whether the very low range of cognitive ability (intellectual disability) is simply one end of the normal distribution describing individual differences in cognitive ability across a population. Here, we examined 40 genes with a known association with non-syndromic autosomal recessive intellectual disability (NS-ARID) to determine if they are enriched for common variants associated with the normal range of intelligence differences. The current study used the 3511 individuals of the Cognitive Ageing Genetics in England and Scotland (CAGES) consortium. In addition, a text mining analysis was used to identify gene sets biologically related to the NS-ARID set. Gene-based tests indicated that genes implicated in NS-ARID were not significantly enriched for quantitative trait loci (QTL) associated with intelligence. These findings suggest that genes in which mutations can have a large and deleterious effect on intelligence are not associated with variation across the range of intelligence differences.

Shared genetic aetiology between cognitive functions and physical and mental health in UK Biobank (N=112 151) and 24 GWAS consortia.

Causes of the well-documented association between low levels of cognitive functioning and many adverse neuropsychiatric outcomes, poorer physical health and earlier death remain unknown. We used linkage disequilibrium regression and polygenic profile scoring to test for shared genetic aetiology between cognitive functions and neuropsychiatric disorders and physical health. Using information provided by many published genome-wide association study consortia, we created polygenic profile scores for 24 vascular-metabolic, neuropsychiatric, physiological-anthropometric and cognitive traits in the participants of UK Biobank, a very large population-based sample (N=112 151). Pleiotropy between cognitive and health traits was quantified by deriving genetic correlations using summary genome-wide association study statistics and to the method of linkage disequilibrium score regression. Substantial and significant genetic correlations were observed between cognitive test scores in the UK Biobank sample and many of the mental and physical health-related traits and disorders assessed here. In addition, highly significant associations were observed between the cognitive test scores in the UK Biobank sample and many polygenic profile scores, including coronary artery disease, stroke, Alzheimer's disease, schizophrenia, autism, major depressive disorder, body mass index, intracranial volume, infant head circumference and childhood cognitive ability. Where disease diagnosis was available for UK Biobank participants, we were able to show that these results were not confounded by those who had the relevant disease. These findings indicate that a substantial level of pleiotropy exists between cognitive abilities and many human mental and physical health disorders and traits and that it can be used to predict phenotypic variance across samples.

The adipokine leptin mediates muscle- and liver-derived IGF-1 in aged mice.

Muscle- and liver-derived IGF-1 play important roles in muscle anabolism throughout growth and aging. Yet, prolonged food restriction is thought to increase longevity in part by lowering levels of IGF-1, which in turn reduces the risk for developing various cancers. The dietary factors that modulate IGF-1 levels are, however, poorly understood. We tested the hypothesis that the adipokine leptin, which is elevated with food intake and suppressed during fasting, is a key mediator of IGF-1 levels with aging and food restriction. First, leptin levels in peripheral tissues were measured in young mice fed ad libitum, aged mice fed ad libitum, and aged calorie-restricted (CR) mice. A group of aged CR mice were also treated with recombinant leptin for 10 days. Later, aged mice fed ad libitum were treated with saline (VEH) or with a novel leptin receptor antagonist peptide (Allo-aca) and tissue-specific levels of IGF-1 were determined. On one hand, recombinant leptin induced a three-fold increase in liver-derived IGF-1 and a two-fold increase in muscle-derived IGF-1 in aged, CR mice. Leptin also significantly increased serum growth hormone levels in the aged, CR mice. On the other, the leptin receptor antagonist Allo-aca did not alter body weight or muscle mass in treated mice compared to VEH mice. Allo-aca did, however, produce a significant (20%) decline in liver-derived IGF-1 as well as an even more pronounced (>50%) decrease in muscle-derived IGF-1 compared to VEH-treated mice. The reduced IGF-1 levels in Allo-aca treated mice were not accompanied by any significant change in growth hormone levels compared to VEH mice. These findings suggest that leptin receptor antagonists may represent novel therapeutic agents for attenuating IGF-1 signaling associated with aging, and could potentially mimic some of the positive effects of calorie restriction on longevity.

Genetic contributions to variation in general cognitive function: a meta-analysis of genome-wide association studies in the CHARGE consortium (N=53949).

General cognitive function is substantially heritable across the human life course from adolescence to old age. We investigated the genetic contribution to variation in this important, health- and well-being-related trait in middle-aged and older adults. We conducted a meta-analysis of genome-wide association studies of 31 cohorts (N=53,949) in which the participants had undertaken multiple, diverse cognitive tests. A general cognitive function phenotype was tested for, and created in each cohort by principal component analysis. We report 13 genome-wide significant single-nucleotide polymorphism (SNP) associations in three genomic regions, 6q16.1, 14q12 and 19q13.32 (best SNP and closest gene, respectively: rs10457441, P=3.93 × 10(-9), MIR2113; rs17522122, P=2.55 × 10(-8), AKAP6; rs10119, P=5.67 × 10(-9), APOE/TOMM40). We report one gene-based significant association with the HMGN1 gene located on chromosome 21 (P=1 × 10(-6)). These genes have previously been associated with neuropsychiatric phenotypes. Meta-analysis results are consistent with a polygenic model of inheritance. To estimate SNP-based heritability, the genome-wide complex trait analysis procedure was applied to two large cohorts, the Atherosclerosis Risk in Communities Study (N=6617) and the Health and Retirement Study (N=5976). The proportion of phenotypic variation accounted for by all genotyped common SNPs was 29% (s.e.=5%) and 28% (s.e.=7%), respectively. Using polygenic prediction analysis, ~1.2% of the variance in general cognitive function was predicted in the Generation Scotland cohort (N=5487; P=1.5 × 10(-17)). In hypothesis-driven tests, there was significant association between general cognitive function and four genes previously associated with Alzheimer's disease: TOMM40, APOE, ABCG1 and MEF2C.

Human cognitive ability is influenced by genetic variation in components of postsynaptic signalling complexes assembled by NMDA receptors and MAGUK proteins.

Differences in general cognitive ability (intelligence) account for approximately half of the variation in any large battery of cognitive tests and are predictive of important life events including health. Genome-wide analyses of common single-nucleotide polymorphisms indicate that they jointly tag between a quarter and a half of the variance in intelligence. However, no single polymorphism has been reliably associated with variation in intelligence. It remains possible that these many small effects might be aggregated in networks of functionally linked genes. Here, we tested a network of 1461 genes in the postsynaptic density and associated complexes for an enriched association with intelligence. These were ascertained in 3511 individuals (the Cognitive Ageing Genetics in England and Scotland (CAGES) consortium) phenotyped for general cognitive ability, fluid cognitive ability, crystallised cognitive ability, memory and speed of processing. By analysing the results of a genome wide association study (GWAS) using Gene Set Enrichment Analysis, a significant enrichment was found for fluid cognitive ability for the proteins found in the complexes of N-methyl-D-aspartate receptor complex; P=0.002. Replication was sought in two additional cohorts (N=670 and 2062). A meta-analytic P-value of 0.003 was found when these were combined with the CAGES consortium. The results suggest that genetic variation in the macromolecular machines formed by membrane-associated guanylate kinase (MAGUK) scaffold proteins and their interaction partners contributes to variation in intelligence.

Cell therapy for ischaemic stroke.

While acute neuroprotection in acute stroke has proven difficult and ended in many failures, there is increasing interest in restorative therapies that target brain remodelling. Cell therapy (transplantation of cells) shows promise, with a growing body of pre-clinical evidence demonstrating improved functional outcomes in animal models; however, questions still remain concerning mechanisms of action. Clinical trials are already underway and will increase in the next few years; their appropriate design and execution along with continued pre-clinical work are necessary for the field to advance and satisfy a large unmet clinical need.

Genotype D amongst injection drug users with acute hepatitis B virus infection in British Columbia.

The eight genotypes of hepatitis B virus (HBV) exhibit distinct geographical distributions. This study identified HBV genotypes and transmission modes associated with acute infection in British Columbia (BC), Canada, from 2001 to 2005. Seventy cases of acute HBV in BC were identified from laboratory reports using a standardized case definition. Interviews for risk factors and hepatitis history were conducted for each case. HBV genotypes were determined by BLAST comparison analysis of the surface (S) or preS gene sequence. To illustrate the distribution of genotypes identified amongst acute cases in BC, an annotated map was produced showing the global occurrence of HBV genotypes. The majority of acute HBV cases occurred in Caucasian, Canadian-born males, with 30% of cases reporting injection drug use (IDU) and 21% reporting incarceration. The most common genotype observed was genotype D (62.9%), followed by genotypes A (18.6%), C (11.4%), B (4.3%), and E (1.4%). A significant association was observed between Genotype D and IDU (P = 0.0025) and previous incarceration (P = 0.0067). Phylogenetic analysis of the S gene sequence demonstrated identical or high genetic relatedness amongst genotype D viral strains (86% sub-genotype D3), thus verifying transmission clustering amongst BC injection drug users. The association between acute HBV genotype and reported transmission modes has not been previously described in North America. Tracking of genotypes can help identify disease transmission patterns and target at-risk populations for preventive immunization.

Differential effects of chronic haloperidol and olanzapine exposure on brain cholinergic markers and spatial learning in rats.

RATIONALE: In psychiatric patients, haloperidol (HAL) induces a number of adverse extrapyramidal and cognitive symptoms, which appear to be less problematic with olanzapine (OLZ). In animals, HAL may initiate a number of harmful effects on central nervous system neurons, including damage to cholinergic pathways - an effect that could be especially deleterious to those experiencing memory dysfunction. The identification of the neurobiological substrates of such effects in animal models may help to improve the algorithms used for proper drug selection especially for long-term neuroleptic use. OBJECTIVES: The aim of this study was to compare the effects of chronic (45-day and 90-day), continuous oral exposure to HAL with OLZ for effects on cognitive performance and cholinergic markers in rats. METHODS: After chronic neuroleptic exposure (and a 4-day washout) spatial memory performance was measured in a water maze task, and choline acetyltransferase (ChAT) immunoreactivity was assessed with immunofluorescence staining. RESULTS: In water maze experiments, HAL and OLZ (relative to vehicle) administered for 90 days (but not 45 days) significantly impaired learning performance (i.e., higher mean latencies across several trials to reach a hidden platform). HAL administered for 90 days was associated with impairment across a greater number of trials than OLZ and it also impaired probe trial performance, as indicated by a reduced number of crossings over the previous platform area (when compared with OLZ or vehicle). Both 45 days and 90 days of HAL treatment reduced ChAT staining in the cortex and hippocampus when compared with OLZ or vehicle. CONCLUSIONS: The results in the rat suggest that OLZ (relative to HAL) may be more desirable as an antipsychotic for patients suffering from memory dysfunction especially for those in which cholinergic deficits may already be present.

Senile plaques exert no mass lesion effect on surrounding neurons.

Since the turn of the century studies have suggested that clinical deterioration in Alzheimer's disease (AD) is accompanied by a gradual increase in both the size and numbers of senile plaques (SP's). Our study investigated the 'mass effect' of SP's on the morphometry of adjacent neurons. For this purpose, we used a computerized image analysis system to study pyramidal cells from the hippocampus of ten AD patients, ten demented schizophrenic (SC) patients and ten cognitively impaired non-AD/non-SC control patients with. We examined cell shape, area and disarray and quantitated the number of SP's and neurofibrillary tangles (NFT's) in the CA1 subfield of the hippocampus. Our results indicated no significant differences between groups for measurements of neuronal shape, size, or disarray. Contrary to earlier reports, our results noted no evidence of pyramidal cell disarray in schizophrenic patients. Our results suggest that SP's incorporate, rather than displace, their surrounding neuropil.

The NF-kappaB inhibitor diethyldithiocarbamate (DDTC) increases brain cell death in a transient middle cerebral artery occlusion model of ischemia.

A transient ischemic middle cerebral artery occlusion model of stroke was used to examine the role of the transcription factor NF-kappaB in cell death as measured by DNA fragmentation and infarction volume. The left middle cerebral artery was occluded for either 30 min or 2 h in rats. One set of animals was pretreated with diethyldithiocarbamate (DDTC), an inhibitor of NF-kappaB, 30 min prior to reperfusion. The animals were reperfused and allowed to survive for 2 or 7 days. DNA fragmentation was assayed by in situ end labeling in the stroke core and penumbral regions. Specific cortical and subcortical regions were measured using quantitative image analysis. DNA fragmentation was seen only on the ischemic side of the brains in all cases. Overall, the DDTC-treated groups showed significantly increased DNA fragmentation within the ischemic side compared to the saline control groups. DDTC treatment also caused an increase in stroke volume based on triphenyl tetrazolium chloride staining. Electrophoretic mobility shift assays showed NF-kappaB activation peaking 15 min following reperfusion and that this activation was blocked by the DDTC treatment. This study suggests that the use of NF-kappaB inhibitors to block cell death following stroke needs to be carefully examined because global inhibitors may not promote neuronal survival.

Long-term antioxidant administration attenuates mineralocorticoid hypertension and renal inflammatory response.

We previously reported increased monocyte/macrophage infiltration, reactive oxygen species accumulation, and nuclear factor-kappaB (NF-kappaB) activation in mineralocorticoid (deoxycorticosterone acetate [DOCA]) hypertensive rats. We tested the hypothesis that prolonged antioxidant administration inhibits superoxide accumulation, lowers blood pressure, and reduces NF-kappaB activation in DOCA-salt hypertensive rats. DOCA rats exhibited a significant increase in systolic blood pressure compared with sham rats. Aortic rings from DOCA rats exhibited increased superoxide (O(2)(-)) production compared with sham rats. In addition, the treatment of DOCA rats with pyrrolidinedithiocarbamate (PDTC) or 4-hydroxy-2,2,6,6-tetramethyl piperidinoxyl (Tempol) caused a significant decrease in systolic blood pressure and aortic superoxide accumulation. Monocyte/macrophage infiltration was also significantly decreased in DOCA rats treated with PDTC or Tempol compared with untreated DOCA rats. NF-kappaB-binding activity was significantly greater in untreated DOCA rats than in either sham rats or PDTC- or Tempol-treated DOCA rats. Also, DOCA rats treated with Tempol exhibited no significant difference in NF-kappaB-binding activity compared with sham. These results suggest that antioxidants attenuate systolic blood pressure, suppress renal NF-kappaB-binding activity, and partly alleviate renal monocyte/macrophage infiltration in DOCA-salt hypertension.