Association analysis of the polymorphism T1128C in the signal peptide of neuropeptide Y in a Swedish hypertensive population

Neuropeptide Y as a risk factor for cardiorenal disease and cognitive dysfunction in CKD: translational opportunities and challenges

Neuropeptide Y (NPY) is a 36-amino-acid peptide member of a family also including peptide YY and pancreatic polypeptide, which are all ligands to Gi/Go coupled receptors. NPY regulates several fundamental biologic functions including appetite/satiety, sex and reproduction, learning and memory, cardiovascular and renal function and immune functions. The mesenteric circulation is a major source of NPY in the blood in man and this peptide is considered a key regulator of gut–brain cross talk. A progressive increase in circulating NPY accompanies the progression of chronic kidney disease (CKD) toward kidney failure and NPY robustly predicts cardiovascular events in this population. Furthermore, NPY is suspected as a possible player in accelerated cognitive function decline and dementia in patients with CKD and in dialysis patients. In theory, interfering with the NPY system has relevant potential for the treatment of diverse diseases from cardiovascular and renal diseases to diseases of the central nervous system. Pharmaceutical formulations for effective drug delivery and cost, as well as the complexity of diseases potentially addressable by NPY/NPY antagonists, have been a problem until now. This in part explains the slow progress of knowledge about the NPY system in the clinical arena. There is now renewed research interest in the NPY system in psychopharmacology and in pharmacology in general and new studies and a new breed of clinical trials may eventually bring the expected benefits in human health with drugs interfering with this system.

Conditional Inactivation of Limbic Neuropeptide Y-1 Receptors Increases Vulnerability to Diet-Induced Obesity in Male Mice

NPY and its Y1 cognate receptor (Y1R) have been shown to be involved in the regulation of stress, anxiety, depression and energy homeostasis. We previously demonstrated that conditional knockout of Npy1r gene in the excitatory neurons of the forebrain of adolescent male mice (Npy1r^rfb mice) decreased body weight growth and adipose tissue and increased anxiety. In the present study, we used the same conditional system to examine whether the targeted disruption of the Npy1r gene in limbic areas might affect susceptibility to obesity and associated disorders during adulthood in response to a 3-week high-fat diet (HFD) regimen. We demonstrated that following HFD exposure, Npy1r^rfb male mice showed increased body weight, visceral adipose tissue, and blood glucose levels, hyperphagia and a dysregulation of calory intake as compared to control Npy1r^2lox mice. These results suggest that low expression of Npy1r in limbic areas impairs habituation to high caloric food and causes high susceptibility to diet-induced obesity and glucose intolerance in male mice, uncovering a specific contribution of the limbic Npy1r gene in the dysregulation of the eating/satiety balance.

The Proline 7 Substitution in the Preproneuropeptide Y Is Associated with Higher Hepatic Lipase Activity In Vivo

Hepatic lipase (HL) functions as a lipolytic enzyme that hydrolyzes triglycerides and phospholipids present in circulating plasma lipoproteins. Plasma HL activity is known to be regulated by hormonal and metabolic factors, but HL responsiveness to insulin as well as its role in modulating atherosclerotic risk is still controversial. We investigated on the influence of a known polymorphism in the neurotransmitter neuropeptide Y (NPY) on HL activity in two different cohorts consisting of diabetic and nondiabetic patients. HL activity was 24% and 34% higher on nondiabetic and diabetic subjects in the presence of the 7Pro allele in NPY, respectively. The presence of the 7Pro allele was an independent predictor of HL activity in multivariate analyses in both cohorts. These data suggest a regulatory effect of NPY on HL activity. Among carriers of the 7Pro allele, we also found a statistically significant lower absolute number of infarctions compared to noncarriers (p < 0.05) and a nonsignificant trend towards less myocardial infarction in the 7Pro allele diabetic carriers (p = 0.085). In conclusion, the common 7Pro allele in NPY was associated with higher HL activity in nondiabetic and diabetic subjects and its presence seems to coincide with a lower frequency of certain cardiovascular events.

Association of Neuropeptide-Y (NPY) and Interleukin-1beta (IL1B), Genotype-Phenotype Correlation and Plasma Lipids with Type-II Diabetes

BACKGROUND

Neuropeptide Y (NPY) is known to play a role in the regulation of satiety, energy balance, body weight, and insulin release. Interleukin-1beta (IL1B) has been associated with loss of beta-cell mass in type-II diabetes (TIID).

OBJECTIVES

The present study attempts to investigate the association of NPY exon2 +1128 T/C (Leu7Pro; rs16139), NPY promoter -399 T/C (rs16147) and IL1B -511 C/T (rs16944) polymorphisms with TIID and their correlation with plasma lipid levels, BMI, and IL1B transcript levels.

METHODS

PCR-RFLP was used for genotyping these polymorphisms in a case-control study involving 558 TIID patients and 1085 healthy age-matched controls from Gujarat. Linkage disequilibrium and haplotype analysis of the NPY polymorphic sites were performed to assess their association with TIID. IL1B transcript levels in PBMCs were also assessed in 108 controls and 101 patients using real-time PCR.

RESULTS

Our results show significant association of both structural and promoter polymorphisms of NPY (p<0.0001 and p<0.0001 respectively) in patients with TIID. However, the IL1B C/T polymorphism did not show any association (p = 0.3797) with TIID patients. Haplotype analysis revealed more frequent association of CC and CT haplotypes (p = 3.34 x 10-5, p = 6.04 x 10-9) in diabetics compared to controls and increased the risk of diabetes by 3.02 and 2.088 respectively. Transcript levels of IL1B were significantly higher (p<0.0001) in patients as compared to controls. Genotype-phenotype correlation of IL1B polymorphism did not show any association with its higher transcript levels. In addition, NPY +1128 T/C polymorphism was found to be associated with increased plasma LDL levels (p = 0.01).

CONCLUSION

The present study provides an evidence for a strong correlation between structural and promoter polymorphisms of NPY gene and upregulation of IL1B transcript levels with susceptibility to TIID and altering the lipid metabolism in Gujarat population.

Neuropeptide Y reduces the expression of PLCB2, PLCD1 and selected PLC genes in cultured human endothelial cells

Endothelial cells (EC) are the first elements exposed to mediators circulating in the bloodstream, and react to stimulation with finely tuned responses mediated by different signal transduction pathways, leading the endothelium to adapt. Neuropeptide Y (NPY), the most abundant peptide in heart and brain, is mainly involved in the neuroendocrine regulation of the stress response. The regulatory roles of NPY depend on many factors, including its enzymatic processing, receptor subtypes and related signal transduction systems, including the phosphoinositide (PI) pathway and related phospholipase C (PI-PLC) family of enzymes. The panel of expression of PI-PLC enzymes differs comparing quiescent versus differently stimulated human EC. Growing evidences indicate that the regulation of the expression of PLC genes, which codify for PI-PLC enzymes, might act as an additional mechanism of control of the PI signal transduction pathway. NPY was described to potentiate the activation of PI-PLC enzymes in different cell types, including EC. In the present experiments, we stimulated human umbilical vein EC using different doses of NPY in order to investigate a possible role upon the expression PLC genes. NPY reduced the overall transcription of PLC genes, excepting for PLCE. The most significant effects were observed for PLCB2 and PLCD1, both isoforms recruited by means of G-proteins and G-protein-coupled receptors. NPY behavior was comparable with other PI-PLC interacting molecules that, beside the stimulation of phospholipase activity, also affect the upcoming enzymes' production acting upon gene expression. That might represent a mode to regulate the activity of PI-PLC enzymes after activation.

Acute central neuropeptide Y administration increases food intake but does not affect hepatic very low-density lipoprotein (VLDL) production in mice

OBJECTIVE

Central neuropeptide Y (NPY) administration stimulates food intake in rodents. In addition, acute modulation of central NPY signaling increases hepatic production of very low-density lipoprotein (VLDL)-triglyceride (TG) in rats. As hypertriglyceridemia is an important risk factor for atherosclerosis, for which well-established mouse models are available, we set out to validate the effect of NPY on hepatic VLDL-TG production in mice, to ultimately investigate whether NPY, by increasing VLDL production, contributes to the development of atherosclerosis.

RESEARCH DESIGN AND METHODS

Male C57Bl/6J mice received an intracerebroventricular (i.c.v.) cannula into the lateral (LV) or third (3V) ventricle of the brain. One week later, after a 4 h fast, the animals received an intravenous (i.v.) injection of Tran(35)S (100 µCi) followed by tyloxapol (500 mg/kg body weight; BW), enabling the study of hepatic VLDL-apoB and VLDL-TG production, respectively. Immediately after the i.v. injection of tyloxapol, the animals received either an i.c.v. injection of NPY (0.2 mg/kg BW in artificial cerebrospinal fluid; aCSF), synthetic Y1 receptor antagonist GR231118 (0.5 mg/kg BW in aCSF) or vehicle (aCSF), or an i.v. injection of PYY3-36 (0.5 mg/kg BW in PBS) or vehicle (PBS).

RESULTS

Administration of NPY into both the LV and 3V increased food intake within one hour after injection (+164%, p<0.001 and +367%, p<0.001, respectively). NPY administration neither in the LV nor in the 3V affected hepatic VLDL-TG or VLDL-apoB production. Likewise, antagonizing central NPY signaling by either PYY3-36 or GR231118 administration did not affect hepatic VLDL production.

CONCLUSION

In mice, as opposed to rats, acute central administration of NPY increases food intake without affecting hepatic VLDL production. These results are of great significance when extrapolating findings on the central regulation of hepatic VLDL production between species.

Interactions of neuropeptide y, catecholamines, and angiotensin at the vascular neuroeffector junction

Work from our laboratory has established that angiotensin II (Ang II) produces a greater enhancement of the nerve stimulation (NS)-induced release (overflow) of both norepinephrine (NE) and neuropeptide Y (NPY) and a greater increase in perfusion pressure of the mesenteric arterial bed obtained from the spontaneously hypertensive rat (SHR) compared to age-matched Wistar-Kyoto (WKY) or Sprague-Dawley rats. The enhancement of NS-induced NPY release was blocked by the AT1 receptor antagonist EMD 66684 and the AT2 receptor antagonist PD 123319. Both captopril and EMD 66684 decreased NPY and NE overflow from SHR mesenteric beds, suggesting an endogenous renin-angiotensin system (RAS) is active in the mesenteric artery. We also observed that the recently discovered new arm of the RAS, namely, angiotensin (1-7) (Ang-(1-7)), attenuated the NS-induced increase in NE and NPY release and the accompanied increased perfusion pressure. These inhibitory effects were greater in blood vessels obtained from SHR compared to WKY. We suggest that inhibition of sympathetic neurotransmission contributes to the mechanism(s) by which Ang-(1-7) acts to inhibit the vasoconstrictor effect of Ang II. Administration of the MAS receptor antagonist D-Ala(7)Ang-(1-7) attenuated the decrease in both NE and NPY release due to Ang-(1-7) administration. The AT2 receptor antagonist PD 123391 attenuated the effect of Ang-(1-7) on NE release without affecting the decrease in NPY release. We observed a shift in the balance between Ang II and Ang-(1-7) levels in the SHR with an increase in Ang II and a decrease in Ang-(1-7) in the blood and mesenteric artery. This appears to be due to an increase in angiotensin-converting enzyme (ACE) in the mesenteric artery of the SHR.

Neuropeptide Y polymorphism increases the risk for asthma in overweight subjects; protection from atherosclerosis in asthmatic subjects--the cardiovascular risk in young Finns study

AIMS

The role of neuropeptide Y (NPY) and its gene polymorphisms in the development of atherosclerosis has become increasingly evident. In asthma, NPY has been shown to be involved as immunomodulator. In this study, we investigated the role of two functional NPY polymorphisms, NPY-Leu7Pro (rs16139) and NPY-399C/T (rs16147) and obesity for the development of asthma as well as atherosclerosis in asthmatic and non-asthmatic subjects. Also, we measured heart rate variability (HRV) and NPY in serum since these might contribute through these polymorphisms to both diseases.

METHODS AND RESULTS

Thousand hundred and seventy six Finnish young adults were genotyped and three groups (G1-G3) were formed based on the observed diplotypes. The NPY-Pro7 allele always co-existed with the NPY-399T allele indicating complete linkage disequilibrium. Here we show that overweight (BMI≥25kg/m2) was associated with 2.5-fold increased risk for asthma in subjects with the NPY-399T allele without NPY-Pro7 allele (G2, n=716). Overweight was also associated with increased atherosclerosis determined by carotid intima media thickness (cIMT), but asthma seemed to be more significant determinant than overweight in determing cIMT having a decreasing effect. NPY concentration in serum was diplotype-driven (G1=792.2(29.5), G2=849.0(18.9), G3=873.9(45.2) pg/ml) and correlated positively with cIMT in the group having NPY-Pro7 allele (G3, n=142). However, the subjects with asthma had a negative NPY-cIMT relationship. Total HRV was increased in asthma and correlated negatively with cIMT irrespective of the NPY genotype.

CONCLUSIONS

Overweight together with the NPY-399T allele without NPY-Pro7 allele was associated with increased risk for asthma. Atherosclerosis was decreased in subjects with asthma depending on the NPY genotype. The results reveal novel insights into the genetics and biology of the relationship of atherosclerosis and asthma.

Neuropeptide Y in the noradrenergic neurons induces the development of cardiometabolic diseases in a transgenic mouse model

Neuropeptide Y (NPY) is a neuropeptide widely expressed in the brain and a peptide transmitter of sympathetic nervous system (SNS) co-released with noradrenaline (NA) in prolonged stress. Association of a gain-of-function polymorphism in the human NPY gene with dyslipideamia, diabetes and vascular diseases suggests that increased NPY plays a role in the pathogenesis of the metabolic syndrome in humans. In the hypothalamus, NPY plays an established role in the regulation of body energy homeostasis. However, the effects of NPY elsewhere in the brain and in the SNS are less explored. In order to understand the role of NPY co-expressed with NA in the sympathetic nerves and brain noradrenergic neurons, a novel mouse model overexpressing NPY in noradrenergic neurons was generated. The mouse displays metabolic defects such as increased adiposity, hepatosteatosis, and impaired glucose tolerance as well as stress-related hypertension and increased susceptibility to vascular wall hypertrophy. The mouse phenotype closely reflects the findings of the several association studies with human NPY gene polymorphisms, and fits with the previous work on the effects of stress-induced NPY release on metabolism and vasculature. Thus, in addition of promoting feeding and obesity in the hypothalamus, NPY expressed in the noradrenergic neurons in the brain and in the SNS induces the development of cardiometabolic diseases.

Polymorphisms in the neuropeptide Y gene and the risk of obesity: findings from two prospective cohorts

CONTEXT

Neuropeptide Y (NPY) increases appetite and food intake in animals. Conflicting evidence has been found for the association between polymorphisms of the NPY gene and obesity in humans.

OBJECTIVE

The objective of the investigation was to study four single-nucleotide polymorphisms (SNPs) in the NPY gene [rs17149106 (G>T), rs16147 (C>T), rs16139 (T>C), rs5574 (C>T)] with body adiposity.

DESIGN

The study design included a candidate gene association study from two cohorts.

PARTICIPANTS

Two thousand seventy-one women from the Nurses' Health Study and 1268 men from the Health Professionals Follow-Up study participated in the study.

MAIN OUTCOME MEASURES

Weight and height were self-reported at baseline and updated every 2 yr to calculate body mass index (BMI).

RESULTS

Two SNPs (rs17149106 (G>T) and rs16139 (T>C)), with minor allele frequencies of 4%, were associated with elevated risks of obesity (BMI ≥ 30 kg/m(2)) in both cohorts. The pooled adjusted odds ratios [95% confidence interval (CI)] were 1.72 (95% CI 1.20-2.47) and 1.79 (95% CI 1.24-2.60), respectively. Haplotype analyses reflected the associations with the individual SNP. TTCC carriers, with the minor allele of both SNPs, had an increased risk of obesity (odds ratio 1.89; 95% CI 1.29-2.75) compared with those carrying the common haplotype GCTT. Carriers of the rs16139 C allele had greater BMI than noncarriers with a pooled mean difference of +0.58 kg/m(2) (95% CI 0.01-1.15) among women and men. Both rs17149106 and rs16139 were associated with weight gain since adolescence/early adulthood but were not associated with abdominal adiposity as measured by waist circumference and waist to hip ratio.

CONCLUSIONS

NPY gene variants were significantly associated with weight changes from young adulthood to middle age and with risk of obesity.

Genetic Association of NPY Gene Polymorphisms with Dampness-Phlegm Pattern in Korean Stroke Patients

Neuropeptide Y (NPY), which is widely expressed in both the central and peripheral nervous systems, has an important role in a variety of biological fields. In this study, we analyzed the distribution of NPY polymorphisms in dampness-phlegm pattern and non-dampness-phlegm pattern in elderly Korean subjects with cerebral infarction (CI). A total of 1.097 subjects (498 normal subjects and 599 CI patients, including 198 with dampness-phlegm pattern and 401 with non-dampness-phlegm pattern) participated in this study. Genotyping for five SNPs (G-1484A, C-1471T, C-399T, A1201G, and C5325T) was conducted by primer extension. The results were statistically analyzed for genetic association of NPY-polymorphisms with normal versus dampness-phlegm pattern or non-dampness-phlegm pattern subjects. Among the five SNPs tested, the T allele of C-399T has a negative association with the dampness-phlegm pattern and is marked by a decrease in serum cholesterol levels. Furthermore, serum cholesterol levels were significantly higher in dampness-phlegm pattern patients than in non-dampness-phlegm pattern patients.In this study, for the first time, the association of NPY polymorphisms with pattern identification (PI) of traditional Korean medicine (TKM) was analyzed in a large CI patient population.

Inflammatory effects of blood leukocytes: association with vascular function in neuropeptide Y proline 7-genotyped type 2 diabetes patients

OBJECTIVE

We investigated the associations of inflammatory blood cell activation with vascular parameters in patients with type 2 diabetes to elucidate the possible mechanisms of accelerated atherosclerosis observed in subjects with the Leucine 7 to Proline 7 polymorphism (Leu7Pro) in the neuropeptide Y (NPY).

METHODS

Our study included 31 Caucasian patients with type 2 diabetes; 12 of them had the Leu7Pro7 (heterozygous), and 19 had the Leu7Leu7 (wild type) genotype. Vascular parameters were determined by ultrasound methods. Leukocyte analyses were performed from blood samples using flow cytometry. NPY concentrations were determined in plasma.

RESULTS

The amount of platelet-granulocyte complexes was positively correlated with NPY concentration (p=0.008) and carotid intima-media thickness (p=0.035) in the Leu7Pro7 group. Interferon gamma (IFN-γ) expression in monocytes correlated negatively with brachial artery flow-mediated dilatation also in the Leu7Pro7 group (p=0.037). The expression of tissue factor on monocytes correlated negatively with brachial artery diameter in the Leu7Pro7 patients as well (p=0.019).

CONCLUSION

The results indicate significant associations between inflammatory cell activation in blood and vascular atherosclerosis in genetically prone subjects, and provide possible mechanistic information about the role of NPY and the Leu7Pro polymorphism in the development of atherosclerosis.

The effect of endogenous preproneuropeptide Y leucine 7 to proline 7 polymorphism on growth and apoptosis in primary cultured HUVECs

Neuropeptide Y (NPY) is a universally expressed neuropeptide involved in the regulation of several physiological functions. The rather common leucine7 to proline7 (L7P) polymorphism in the signal peptide of preproNPY is a functional substitution, which changes the processing and release of NPY in cells. The mutation is associated with altered lipid levels and accelerated atherosclerosis in humans. Based on previous studies, we investigated the effect of the Pro7 allele in endothelial cells, which are known to play a role in the development of atherosclerosis. Cell proliferation and apoptosis were studied in primary cultured, genotyped human umbilical vein endothelial cells (HUVECs). Our results indicate that cells with the [p.L7]+[p.P7] genotype seem to have a tendency to be more sensitive to the growth stimulating effect of NPY and less sensitive to the effect of vascular endothelial growth factor compared to cells with the [p.L7]+[p.L7] genotype. Additionally, cells with the [p.L7]+[p.P7] genotype seem to be more sensitive to apoptosis than [p.L7]+[p.L7] cells. We speculate that the L7P substitution in preproNPY might cause a state of cellular pre-senescence, leading to endothelial dysfunction. This might be one reason for the associations of the L7P polymorphism with atherosclerosis and type II diabetes found in clinical studies.

Association of the C-399T promoter polymorphism of neuropeptide Y with susceptibility to ischemic stroke

OBJECTIVES

The common sequence variants of neuropeptide Y (NPY) were known to be associated with some kinds of diseases including stroke. This study investigated the association of NPY promoter polymorphism, C-399T, with ischemic stroke and its underlying mechanism using in vitro systems.

DESIGN AND METHODS

Study subjects consisted of 444 ischemic stroke patients and 326 controls without stroke. C-399T genotyping was conducted by a primer extension-based method. Plasma NPY was quantified with an enzyme immunoassay, and transcription characteristics were investigated by a reporter gene assay and an enzyme mobility shift assay.

RESULTS

A significantly lower frequency of TT genotype was observed in a stroke group (OR[95% CI], 0.399[0.187-0.854], p=0.0180). The C-399T polymorphism affected the transcription efficiency of NPY gene and its genotypes were related to the changes in plasma NPY levels.

CONCLUSION

This study suggests that NPY promoter polymorphism, C-399T, should be considered a genetic risk factor for ischemic stroke.

Sympathetic nervous system-targeted neuropeptide Y overexpression in mice enhances neointimal formation in response to vascular injury

Sympathetic neurotransmitter neuropeptide Y (NPY) is associated with vascular remodelling, neointimal hyperplasia and atherosclerosis in experimental animal models and clinical studies. In order to study the role of sympathetic nerve-produced NPY in vascular diseases, transgenic mouse model overexpressing NPY in central and peripheral noradrenergic neurons under the dopamine-beta-hydroxylase (DBH) promoter was recently created (OE-NPY(DBH) mouse). This study aimed to examine the effect of NPY overexpression on arterial neointimal hyperplasia in an experimental model of vascular injury. Transgenic OE-NPY(DBH) mice and wildtype control mice of two different inbred strains (C57BL/6 and FVB/n) underwent a femoral artery surgery with a transluminar injury by a 0.38-mm guide wire insertion. Arteries were harvested 4 weeks from the surgery, and they were stained for basic morphology. Both strains of OE-NPY(DBH) mice, as compared with wildtype control mice, showed on average 50% greater formation of the neointima (P<0.01) and an increase in the medial area (P=0.05). The results suggest that moderately increased neuronal NPY causes the arteries to be more susceptible to femoral artery thickening after endothelial injury. The OE-NPY(DBH) mouse provides a novel tool to explore the role of NPY in the development of vascular disease related to metabolic disorders.

The role of non-synonymous NPY gene polymorphism in the nitric oxide production in HUVECs

A Leu7Pro change in the signal peptide of preproNPY is a functional substitution, which changes the processing of NPY in cells and associates with several cardiovascular and metabolic conditions in humans. The current study investigates the effect of the P7 allele in endothelial cells, where decreased nitric oxide (NO) production is a promoting factor to endothelial dysfunction. The function of NO system was assessed in the human umbilical vein endothelial cells (HUVECs) with [p.L7]+[p.L7] or [p.L7]+[p.P7] genotype. NPY seems to have a significant influence on NO system in HUVECs, and the responses are time and genotype dependent. HUVECs with [p.L7]+[p.P7] genotype seem to have higher basal production of NO, but after a long term treatment with NPY these cells express less eNOS mRNA and overall eNOS protein levels are lower. These significant differences in the NO bioavailability may explain the association of the L7P polymorphism with several cardiovascular complications.

Neuropeptide Y gene polymorphisms confer risk of early-onset atherosclerosis

Neuropeptide Y (NPY) is a strong candidate gene for coronary artery disease (CAD). We have previously identified genetic linkage to familial CAD in the genomic region of NPY. We performed follow-up genetic, biostatistical, and functional analysis of NPY in early-onset CAD. In familial CAD (GENECARD, N = 420 families), we found increased microsatellite linkage to chromosome 7p14 (OSA LOD = 4.2, p = 0.004) in 97 earliest age-of-onset families. Tagged NPY SNPs demonstrated linkage to CAD of a 6-SNP block (LOD = 1.58-2.72), family-based association of this block with CAD (p = 0.02), and stronger linkage to CAD in the earliest age-of-onset families. Association of this 6-SNP block with CAD was validated in: (a) 556 non-familial early-onset CAD cases and 256 controls (OR 1.46-1.65, p = 0.01-0.05), showing stronger association in youngest cases (OR 1.84-2.20, p = 0.0004-0.09); and (b) GENECARD probands versus non-familial controls (OR 1.79-2.06, p = 0.003-0.02). A promoter SNP (rs16147) within this 6-SNP block was associated with higher plasma NPY levels (p = 0.04). To assess a causal role of NPY in atherosclerosis, we applied the NPY1-receptor-antagonist BIBP-3226 adventitially to endothelium-denuded carotid arteries of apolipoprotein E-deficient mice; treatment reduced atherosclerotic neointimal area by 50% (p = 0.03). Thus, NPY variants associate with atherosclerosis in two independent datasets (with strong age-of-onset effects) and show allele-specific expression with NPY levels, while NPY receptor antagonism reduces atherosclerosis in mice. We conclude that NPY contributes to atherosclerosis pathogenesis.

Neuropeptide Y and alpha-melanocyte-stimulating hormone: interaction in obesity and possible role in the development of hypertension

AIM

Obesity and hypertension frequently coexist and both represent important risk factors for cardiovascular disease. The mechanisms implicated in the regulation of food intake have not been completely elucidated. Recent data suggests that peripheral and central neuropeptides play an important role in the maintenance of energy balance. More specifically, leptin, neuropeptide Y (NPY) and alpha-melanocyte-stimulating hormone (a-MSH) appear to be implicated in the pathogenesis of obesity and also contribute to the development of hypertension in obesity.

METHODS

Analysis of the pertinent bibliography published in PubMed database.

RESULTS

Leptin is produced in the adipose tissue directly correlated with fat tissue mass. Leptin acts on two distinct neural populations in the hypothalamus: the first expresses the orexigenic peptides NPY and agouti-related protein (AgRP), the second pro-opiomelanocortin (POMC). The activation of POMC neurons increases the production of the anorexigenic hormone a-MSH and inhibits the release of NPY and AgRP. In addition, the hypothalamus integrates the neuroendocrine systems with the autonomic nervous system and controls the activity of the latter. Stimulation of hypothalamic nuclei elicits sympathetic responses including blood pressure elevation. Both NPY and a-MSH appears to be implicated in the hypothalamic regulation of sympathetic nervous system (SNS) activity.

CONCLUSION

Alterations in leptin, NPY and a-MSH are frequently observed in obesity and might stimulate SNS activity, contributing to the development of hypertension in obese patients. These neuropeptides might provide a pathophysiologic link between excess weight and hypertension. However, more research is needed before the pharmacologic manipulation of these complex neuroendocrine systems can be applied in the treatment of obesity and hypertension.

Genome-wide linkage analysis of pulse pressure in American Indians: the Strong Heart Study

BACKGROUND

Pulse pressure, a measure of central arterial stiffness and a predictor of cardiovascular mortality, has known genetic components.

METHODS

To localize the genetic effects of pulse pressure, we conducted a genome-wide linkage analysis of 1,892 American-Indian participants of the Strong Heart Family Study (SHFS). Blood pressure was measured three times and the average of the last two measures was used for analyses. Pulse pressure, the difference between systolic blood pressure (SBP) and diastolic blood pressure (DBP), was log-transformed and adjusted for the effects of age and sex within each study center. Variance component linkage analyses were performed using marker allele frequencies derived from all individuals and multipoint identity-by-descent matrices calculated in Loki.

RESULTS

We identified a quantitative-trait locus influencing pulse pressure on chromosome 7 at 37 cM (marker D7S493, LOD = 3.3) and suggestive evidence of linkage on chromosome 19 at 92 cM (marker D19S888, LOD = 1.8).

CONCLUSIONS

The signal on 7p15.3 overlaps positive findings for pulse pressure among Utah population samples, suggesting that this region may harbor gene variants for blood pressure related traits.

An Interactive Association of Common Sequence Variants in the Neuropeptide Y Gene With Susceptibility to Ischemic Stroke

Background and Purpose— Knowledge of the genetic architecture of ischemic stroke has been quite limited. Most significant associations of candidate genes with ischemic stroke have been difficult to replicate. This might be because the associations were not strong enough for results to be consistent, and testing a mixture of heterogeneous ischemic strokes might lead to confounded genetic associations.

Methods— A preliminary association analysis with 28 sequence variants in 18 candidate genes ( ACE, AGT, AGTR1, BDNF, CRP, F13B, LIF, MMP9, NPPA, NPY, PTGS2, SELP, SERPINE1, SREBF2, TFPI, THBD, VCAM1 , and VEGF ) revealed that NPY might be the most responsible for the susceptibility of ischemic stroke. Forty-five variants were discovered in the NPY gene by full sequencing, and 5 polymorphisms were selected based on their allele frequency and linkage disequilibrium estimates to conduct a thorough examination of their associations with ischemic stroke and its subtypes classified by TOAST. This study was conducted with 271 patients with ischemic stroke and 455 control subjects.

Results— In contrast to a slight significance for an allelic association with ischemic stroke, remarkable discrepancies between haplotype frequencies of control subjects and patients were found. Especially, TA and CC of the haplotypes composed of C4112T and A6411C in the NPY gene were associated with increased risk ( P =1.8×10 −21 , P =2.0×10 −13 ). The interchanged haplotypes, TC and CA, were protective against the diseases ( P =9.3×10 −12 , P =6.0×10 −17 ). The associations were also shown in major subtypes of ischemic stroke.

Conclusions— This remarkable haplotypic association suggested that the interaction between the 2 common sequence polymorphisms in NPY contributed to a great amount of phenotypic variability of ischemic stroke.

Cardiovascular Biomarkers in CKD: Pathophysiology and Implications for Clinical Management of Cardiac Disease

Cardiovascular disease (CVD) is a major cause of morbidity and mortality in patients with all forms of chronic kidney disease (CKD). The underlying pathological state is caused by a complex interplay of traditional and nontraditional risk factors that results in atherosclerosis, arteriosclerosis, and altered cardiac morphological characteristics. This multifactorial disease introduces new challenges in predicting and treating patients with CVD sufficiently early in the course of CKD to positively alter patient outcome. Asymptomatic individuals with progressive CVD are a group of patients that deserve focused attention because early detection and intervention may provide the best opportunity for improved outcome. However, identifying CVD in asymptomatic patients with CKD or end-stage renal disease remains a significant hurdle in the management of these patients. Recently, a number of cardiovascular biomarkers were identified as predictors of patient outcome in individuals with CVD and, with additional research, may be used to guide the early diagnosis of and therapy for CVD in patients with CKD. This review examines the pathophysiological characteristics and potential clinical role of these novel cardiovascular biomarkers in risk stratification, risk monitoring, and selection of preventive therapies for patients with CKD.

The T1128C polymorphism of neuropeptide Y gene in a chinese population

BACKGROUND

Several papers have shown that the T1128C polymorphism of the neuropeptide Y (NPY) gene was related to certain diseases and disorders. However, the allele frequency of the 1128C showed significant differences among some populations with different genetic backgrounds, being absent in Japanese and Korean populations. Therefore, this present study was aimed to explore whether the T1128C polymorphism of the NPY gene exists in a Chinese population.

METHODS

A total of 304 newly diagnosed inpatients with coronary heart disease (CHD) were selected as the subjects in the present study. Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis was performed to detect the T1128C polymorphism.

RESULTS

Of the 304 CHD patients, only one patient showed the T1128/C1128 genotype in the NPY gene, the others were all the T1128/T1128 genotype.

CONCLUSIONS

The T1128C polymorphism of the NPY gene is population specific and extremely low in a Chinese population.

Polymorphism in neuropeptide Y influences CSF cholesterol levels but is no major risk factor of Alzheimer's disease

Neuropeptide Y (NPY) is a neurotransmitter expressed in the central nervous system and involved in learning and memory. The NPY L7P polymorphism has been associated with altered cholesterol levels in obese patients. Since altered cholesterol metabolism is also involved in Alzheimer's disease (AD), the effects of two NPY polymorphisms (L7P and IVS1-100 T/G) on CSF and plasma cholesterol and 24S-hydroxycholesterol were investigated in AD patients and non-demented controls. Furtheremore, the effect of both NPY polymorphisms on the risk of AD was studied. The NPY IVS1-100 T/G polymorphism influenced CSF levels of cholesterol, whereas CSF and plasma levels of 24S-hydroxycholesterol and plasma cholesterol were not altered by genotype. NPY L7P polymorphism did not influence CSF or plasma cholesterol or 24S-hydroxycholesterol. Both NPY polymorphisms did not influence the risk of AD. Our data support the observation, that NPY polymorphisms might influence cholesterol metabolism, but might not act as major risk factor in AD.

The Leu7Pro polymorphism of preproNPY is associated with decreased insulin secretion, delayed ghrelin suppression, and increased cardiovascular responsiveness to norepinephrine during oral glucose tolerance test

CONTEXT

Neuropeptide Y (NPY) plays a role in angiogenesis, cardiovascular regulation, and hormone secretion. The leucine7 to proline7 (Leu7Pro) polymorphism of preproNPY is associated with vascular diseases and has an impact on hormone levels in healthy subjects.

OBJECTIVE

The current study investigated the role of the Leu7Pro polymorphism in metabolic and cardiovascular autonomic regulation.

DESIGN AND SUBJECTS

A 5-h oral glucose tolerance test was performed on 27 healthy volunteers representing two preproNPY genotypes (Leu7/Pro7 and Leu7/Leu7) matched for age, sex, body mass index and physical activity.

MAIN OUTCOME MEASURES

Simultaneously we performed cardiovascular autonomic function tests and plasma measurements of sympathetic transmitters, glucose, insulin, and ghrelin.

RESULTS

The subjects with Leu7/Pro7 genotype had decreased plasma NPY, norepinephrine (NE), and insulin concentrations and insulin to glucose ratios. The suppression of ghrelin concentrations after glucose ingestion was delayed in these subjects. They also had increased heart rate variability indices and baroreflex sensitivity. However, they displayed significant negative association of NE concentration with variability of low-frequency R-R-intervals and with baroreflex sensitivity.

CONCLUSIONS

The Leu7Pro polymorphism of preproNPY is related to decreased level of basal sympathetic activity, decreased insulin secretion, and delayed ghrelin suppression during oral glucose tolerance test. The increased responsiveness of autonomic functions to NE associated with the polymorphism may be connected to increased cardiovascular vulnerability.

Neuropeptide Y as a far-reaching neuromediator: from energy balance and cardiovascular regulation to central integration of weight and bone mass control mechanisms. Implications for human diseases

PURPOSE OF REVIEW

I review recent knowledge on the interference of neuropeptide Y with energy balance and cardiovascular and renal disease and on the central regulation of bone mass.

RECENT FINDINGS

Although neuropeptide Y is mainly seen as a vasoconstrictor, rats overexpressing the neuropeptide Y gene show reduced blood pressure and longer life span in comparison with control rats. Due to its strong mitogenic effects on vascular smooth muscle cells, neuropeptide Y induces occlusive lesions in a rat model of atherosclerosis induced by balloon angioplasty. The involvement of neuropeptide Y in experimental atherosclerosis is complex and may include also favourable, compensatory, mechanisms because, at physiological concentrations, it also activates a potent neoangiogenic response to ischemia. Subjects with a common genotype in the neuropeptide Y gene, which underlies increased intracellular neuropeptide Y storage, display slightly raised blood pressure, high serum cholesterol and increased carotid intima media thickness. In patients with end-stage renal disease high neuropeptide Y in plasma has been associated consistently with concentric left-ventricular hypertrophy and cardiovascular mortality. Finally, recent studies have shown that neuropeptide Y constitutes an important central regulator of bone mass and that it may be involved in inflammation and immune regulation.

SUMMARY

Evidence has accrued in experimental animals that altered neuropeptide Y is involved in obesity and the attendant metabolic complications. Recent data also suggest that this peptide may play a role in atherosclerosis and related cardiovascular complications.