Pharmacology of neuropeptide Y receptor antagonists. Focus on cardiovascular functions

Autonomic modulation of ventricular electrical activity: recent developments and clinical implications

PURPOSE

This review aimed to provide a complete overview of the current stance and recent developments in antiarrhythmic neuromodulatory interventions, focusing on lifethreatening vetricular arrhythmias.

METHODS

Both preclinical studies and clinical studies were assessed to highlight the gaps in knowledge that remain to be answered and the necessary steps required to properly translate these strategies to the clinical setting.

RESULTS

Cardiac autonomic imbalance, characterized by chronic sympathoexcitation and parasympathetic withdrawal, destabilizes cardiac electrophysiology and promotes ventricular arrhythmogenesis. Therefore, neuromodulatory interventions that target the sympatho-vagal imbalance have emerged as promising antiarrhythmic strategies. These strategies are aimed at different parts of the cardiac neuraxis and directly or indirectly restore cardiac autonomic tone. These interventions include pharmacological blockade of sympathetic neurotransmitters and neuropeptides, cardiac sympathetic denervation, thoracic epidural anesthesia, and spinal cord and vagal nerve stimulation.

CONCLUSION

Neuromodulatory strategies have repeatedly been demonstrated to be highly effective and very promising anti-arrhythmic therapies. Nevertheless, there is still much room to gain in our understanding of neurocardiac physiology, refining the current neuromodulatory strategic options and elucidating the chronic effects of many of these strategic options.

Coronary Sinus Neuropeptide Y Levels and Adverse Outcomes in Patients With Stable Chronic Heart Failure

Question

Is the adrenergic cotransmitter neuropeptide Y (NPY) associated with outcomes in patients with stable heart failure (HF)?

Findings

In a cohort of patients with stable HF undergoing cardiac resynchronization therapy device implantation, coronary sinus blood was sampled for NPY levels. A threshold level of NPY was identified, which was associated with death, heart transplant, and ventricular assist device placement; molecular studies on human sympathetic neurons indicated increased release of NPY in HF patients.

Meaning

Using NPY, hyperadrenergic activation associated with adverse outcomes may be identifiable in patients with stable HF.

Importance

Chronic heart failure (CHF) is associated with increased sympathetic drive and may increase expression of the cotransmitter neuropeptide Y (NPY) within sympathetic neurons.

Objective

To determine whether myocardial NPY levels are associated with outcomes in patients with stable CHF.

Design, Setting, and Participants

Prospective observational cohort study conducted at a single-center, tertiary care hospital. Stable patients with heart failure undergoing elective cardiac resynchronization therapy device implantation between 2013 and 2015.

Main Outcomes and Measures

Chronic heart failure hospitalization, death, orthotopic heart transplantation, and ventricular assist device placement.

Results

Coronary sinus (CS) blood samples were obtained during cardiac resynchronization therapy (CRT) device implantation in 105 patients (mean [SD] age 68 [12] years; 82 men [78%]; mean [SD] left ventricular ejection fraction [LVEF] 26% [7%]). Clinical, laboratory, and outcome data were collected prospectively. Stellate ganglia (SG) were collected from patients with CHF and control organ donors for molecular analysis. Mean (SD) CS NPY levels were 85.1 (31) pg/mL. On bivariate analyses, CS NPY levels were associated with estimated glomerular filtration rate (eGFR; r_s = −0.36, P < .001); N-terminal–pro hormone brain natriuretic peptide (r_s = 0.33; P = .004), and LV diastolic dimension (r_s = −0.35; P < .001), but not age, LVEF, functional status, or CRT response. Adjusting for GFR, age, and LVEF, the hazard ratio for event-free (death, cardiac transplant, or left ventricular assist device) survival for CS NPY ≥ 130 pg/mL was 9.5 (95% CI, 2.92-30.5; P < .001). Immunohistochemistry demonstrated significantly reduced NPY protein (mean [SD], 13.7 [7.6] in the cardiomyopathy group vs 31.4 [3.7] in the control group; P < .001) in SG neurons from patients with CHF while quantitative polymerase chain reaction demonstrated similar mRNA levels compared with control individuals, suggesting increased release from SG neurons in patients with CHF.

Conclusions and Relevance

The CS levels of NPY may be associated with outcomes in patients with stable CHF undergoing CRT irrespective of CRT response. Increased neuronal traffic and release may be the mechanism for elevated CS NPY levels in patients with CHF. Further studies are warranted to confirm these findings.

Trial Registration

ClinicalTrials.gov identifier: NCT01949246

Neuropeptide Y receptors in carotid plaques of symptomatic and asymptomatic patients: effect of inflammatory cytokines

AIMS

Cytokines released by the immune cells at the site of plaque milieu induce smooth muscle cell apoptosis to promote plaque instability. But, neuropeptide Y (NPY), a pleotropic factor, may modulate the effects of cytokines in atherosclerotic plaques of patients with carotid stenosis. Our aim was to investigate the relative expression of NPY-Y1, NPY-Y2 and NPY-Y5 receptors on carotid plaque vascular smooth muscle cells (pVSMCs) of symptomatic (S) and asymptomatic (AS) patients and examine the effect of inflammatory cytokines on the expression of NPY receptors, that may attenuate plaque rupture.

METHODS AND RESULTS

In healthy carotid artery, there were significantly increased immunopositivity and increased mRNA transcripts of NPY-Y1 and NPY-Y5 receptors in thin sections and isolated VSMCs, respectively, compared to S and AS plaques. However, the NPY-Y2 expression was higher in S and AS pVSMCs than controls. Stimulation of the cells with TNF-α, IL-12 or IFN-γ (50 ng/ml) decreased mRNA transcripts of NPY-Y1 and NPY-Y5 and increased NPY-Y2 mRNAs in VSMCs of healthy carotid artery. The effect of the cytokines on mRNA transcripts of NPY-Y5 and NPY-Y2 in pVSMCs of S and AS patients was similar to healthy VSMCs, but with variable effect on NPY-Y1.

CONCLUSION

Increased expression of NPY-Y2 receptors in symptomatic pVSMCs than in healthy and asymptomatic subjects suggests a potential role of NPY-Y2 in plaque instability. This is further supported by the pronounced effect of atheroma-associated cytokines to increase NPY-Y2 mRNA transcripts in pVSMCs of patients with carotid stenosis.

Role of neuropeptide Y in the regulation of kidney function

The presence in the mammalian kidney of NPY and at least one of its receptor subtypes has been proven by several independent methodologies. Also, numerous studies using physiological and pharmacological approaches indicated that this peptide has the capacity to alter renal function. In particular, these studies suggest that NPY may exert renal vasoconstrictor and tubular actions that are species dependent, and may also influence renin secretion by the kidney. The question whether NPY plays an important role in the physiological regulation of renal hemodynamics and electrolyte excretion, remains largely unanswered at present. No major impairments in renal function have been reported in genetically models deficient in NPY or its Y1 receptor. Thus, additional studies are required to elucidate the role of NPY in the physiological and pathophysiological regulation of renal function.

Selective increase of dark phase water intake in neuropeptide-Y Y2 and Y4 receptor knockout mice

Neuropeptide-Y (NPY) is involved in the regulation of ingestive behaviour and energy homeostasis. Since deletion of the NPY Y2 and Y4 receptor gene increases and decreases food intake, respectively, we examined whether water intake during the light and dark phases is altered in Y2 and Y4 receptor knockout mice. The water consumption of mice staying in their home cages was measured by weighing the water bottles at the beginning and end of the light phase during 4 consecutive days. Control, Y2 and Y4 receptor knockout mice did not differ in their water intake during the light phase. However, during the dark phase Y2 and Y4 receptor knockout mice drank significantly more (46-63%, P<0.05) water than the control mice. The total daily water intake over 24 h was also enhanced. The enhanced water intake during the dark phase was not altered by the beta-adrenoceptor antagonist propranolol or the angiotensin AT1 receptor antagonist telmisartan (each injected intraperitoneally at 10 mg/kg). These data indicate that NPY acting via Y2 and Y4 receptors plays a distinctive role in the regulation of nocturnal water consumption. While beta-adrenoceptors and angiotensin AT1 receptors do not seem to be involved, water intake in Y2 and Y4 receptor knockout mice may be enhanced because presynaptic autoinhibition of NPY release and inhibition of orexin neurons in the central nervous system are prevented.

Behavioural, neural and cardiovascular adaptations in mice lacking the NPY Y1 receptor

Neuropeptide Y (NPY) is primarily synthesised and released by neurones, it is co-localised with noradrenaline and is involved in the regulation of cardiovascular function. In a mouse model lacking NPY Y1 receptor (KO), the ability of NPY to potentiate noradrenaline-induced vasoconstriction is abolished during stress but normal in baseline conditions, locomotor activity and metabolic rate are lowered, blood insulin levels and glucose storage activity are increased. The present study was aimed at further characterising NPY Y1 mutants, with special emphasis on: behavioural responses to novelty seeking and open-field with objects tests, heart rate responsiveness during acute social defeat, alpha2-adrenoceptor (alpha2-ARs) function in brain areas involved in cardiovascular regulation, and cardiac structure. As compared to wild-type controls (n=9), NPY Y1 KOs (n=9) showed: reduced somatomotor activation during non-social challenges, lower heart rate in baseline conditions, larger heart rate responsiveness during social defeat, increased number of alpha2-ARs in the dorsal motor nucleus of the vagus (nX) and the locus coeruleus (LC), moderately larger volume fraction of myocardial fibrosis. The remarkable increment of alpha2-adrenoceptor density in the nX and LC allows to view KO mice behavioural and anatomo-physiological peripheral characteristics as 'adaptations' to central adrenergic rearrangement due to NPY Y1 receptor deletion.

Neuropeptide Y and Leptin in Patients with Obstructive Sleep Apnea Syndrome

Neuropeptide Y (NPY) and leptin are two peptides involved in the regulation of body weight, energy balance, and sympathetic tone. This study investigates the independent role of apneas and obesity on NPY and leptin plasma levels in patients with obstructive sleep apnea syndrome (OSAS). To this end we compared their values in 23 obese (body mass index > 30 kg/m2) and 24 nonobese (body mass index < 27 kg/m2) patients with OSAS, and in 19 obese and 18 nonobese control subjects without OSAS. Patients who used continuous positive airway pressure for more than 4 hours/night were reexamined 3 and 12 months later. We found that NPY levels were increased (p < 0.01) in patients with OSAS independently of obesity. Leptin levels were also increased in OSAS but this was mostly associated to obesity. Continuous positive airway pressure treatment reduced NPY levels in all patients and leptin levels only in nonobese patients (p < 0.01). We concluded that NPY and leptin plasma levels are increased in patients with OSAS. Yet, whereas the former appear independent of obesity, the latter are mostly associated with obesity.

Neuropeptide Y (NPY)

Neuropeptides such as neuropeptide Y (NPY) have long been proposed to play a role in the pathogenesis of inflammatory diseases. NPY is a 36 amino acid neuropeptide which participates in the regulation of a large number of physiological and pathophysiological processes in the cardiorespiratory system, immune system, nervous system and endocrine system. Serum levels of NPY are increased during exacerbations of asthma, whereas the number of NPY-immunoreactive nerves in the airways remains constant in the airways of patients with inflammatory airway diseases such asthma or rhinitis. Next to a role in the regulation of glandular activity, NPY exerts a major influence on humoral and cellular immune functions. In this respect, NPY is known to modulate potent immunological effects such as immune cell distribution, T helper cell differentiation, mediator release, or natural killer cell activation. In addition to these direct effects, NPY also acts as an immunomodulator by influencing the effects of a variety of other neurotransmitters. Whereas the peptide has been focused for therapeutic options in the central nervous system, a potential use in the treatment of pulmonary inflammatory disorders has not been revealed so far due to the complex pulmonary effects of NPY. However, since selective antagonists and agonists and gene-depleted animals for the different receptors are now available, NPY may be of value for future strategies in airway nerve modulation.

Increased expression of the gene for the Y1 receptor of neuropeptide Y in the amygdala and paraventricular nucleus of Y1R/LacZ transgenic mice in response to restraint stress

A sustained increase in the brain concentrations of neuroactive steroids was previously shown to induce Y1 receptor gene expression in the amygdala of Y1R/LacZ transgenic mice which harbour a construct comprising the murine Y1 receptor gene promoter and the lacZ reporter gene. We now investigated the effects of restraint stress on both the cerebrocortical concentrations of neuroactive steroids and Y1 receptor gene expression in the amygdala and hypothalamic paraventricular nucleus (PVN) of Y1R/LacZ transgenic mice. The cerebrocortical concentrations of allopregnanolone and allotetrahydrodeoxycorticosterone were significantly increased immediately after a 1-h exposure to restraint stress and had returned to control values within 30 min. Expression of Y1R/LacZ was increased in the amygdala and PVN 6 h after restraint. The 5alpha-reductase inhibitor finasteride, that prevented the increase in neuroactive steroid concentrations, did not block that in transgene expression induced by 1-h restraint. Daily exposure to restraint for 10 days also increased the cerebrocortical concentrations of neuroactive steroids but failed to affect transgene expression. Acute but not repeated restraint thus increases Y1 receptor gene expression in the amygdala and PVN, suggesting that tolerance develops towards this stressor. The effect of acute restraint is not mediated by the increase in the brain concentrations of neuroactive steroids but may rather reflect a ligand-induced increase in Y1 receptor gene transcription. Data support a role of Y1 receptors in the behavioural and neuroendocrine responses to stress.

Characterization of N-(1-Acetyl-2,3-dihydro-1H-indol-6-yl)-3-(3-cyano-phenyl)-N-[1-(2-cyclopentyl-ethyl)-piperidin-4yl]acrylamide (JNJ-5207787), a small molecule antagonist of the neuropeptide Y Y2 receptor

The in vitro pharmacological properties of N-(1-Acetyl-2,3-dihydro-1H-indol-6-yl)-3-(3-cyano-phenyl)-N-[1-(2-cyclopentyl-ethyl)-piperidin-4yl]-acrylamide (JNJ-5207787), a novel neuropeptide Y Y(2) receptor (Y(2)) antagonist, were evaluated. JNJ-5207787 inhibited the binding of peptide YY (PYY) to human Y(2) receptor in KAN-Ts cells (pIC(50) = 7.00 +/- 0.10) and to rat Y(2) receptors in rat hippocampus (pIC(50) = 7.10 +/- 0.20). The compound was >100-fold selective versus human Y(1),Y(4), and Y(5) receptors as evaluated by radioligand binding. In vitro receptor autoradiography data in rat brain tissue sections confirmed the selectivity of JNJ-5207787. [(125)I]PYY binding sites sensitive to JNJ-5207787 were found in rat brain regions known to express Y(2) receptor (septum, hypothalamus, hippocampus, substantia nigra, and cerebellum), whereas insensitive binding sites were observed in regions known to express Y(1) receptor (cortex and thalamus). JNJ-5207787 was demonstrated to be an antagonist via inhibition of PYY-stimulated guanosine 5'-O-(3-[(35)S]thio)triphosphate binding ([(35)S]GTPgammaS) in KAN-Ts cells (pIC(50) corrected = 7.20 +/- 0.12). This was confirmed auto-radiographically in rat brain sections where PYY-stimulated guanosine 5'-O-(3-[(35)S]thio)triphosphate binding was inhibited by JNJ-5207787 (10 microM) in hypothalamus, hippocampus, and substantia nigra. After intraperitoneal administration in rats (30 mg/kg), JNJ-5207787 penetrated into the brain (C(max) = 1351 +/- 153 ng/ml at 30 min) and occupied Y(2) receptor binding sites as revealed by ex vivo receptor autoradiography. Hence, JNJ-5207787 is a potent and selective pharmacological tool available to establish the potential role of central and peripheral Y(2) receptors in vivo.

The ability of neuropeptide Y to mediate responses in the murine cutaneous microvasculature: an analysis of the contribution of Y1 and Y2 receptors

1. The ability of neuropeptide Y (NPY) to modulate skin blood flow, oedema formation and neutrophil accumulation was investigated. Experiments were designed to examine the possible contribution of the Y2 receptor, in addition to the Y1 receptor, through use of Y2 receptor knockout mice (Y2-/-) and selective receptor antagonists. 2. The development of a 99mTc clearance technique for the measurement of microvascular blood flow changes in mouse dorsal skin revealed a dose-dependent ability of picomole amounts of NPY, and also of the Y1-preferred agonist Pro34NPY and the Y2-preferred agonist PYY(3-36) to decrease blood flow. 3. The Y1 receptor antagonist BIBO3304 blocked responses to the Y1 agonist at the lower doses, but only partially inhibited at the higher doses tested in Y2+/+. In Y2-/- receptor mice, the responses to the Y2 agonist were abolished at the lower doses and partially reduced at the highest dose tested, while those to the Y1 agonist were similar in both Y2+/+ and Y2-/-receptor mice. 4. In Y2+/+ receptor mice, the simultaneous injection of the Y2 antagonist BIIE0246 with BIBO3304 abolished Y2 agonist-induced decreases in blood flow over the dose range used (10-100 pmol). When the Y2 receptor antagonist BIIE0246 was given alone, it was not able to significantly affect the PYY(3-36)-induced response, whereas the Y1 receptor antagonist BIBO3304 partially (P<0.001) inhibited the decrease in blood flow evoked by PYY(3-36) at the highest dose. 5. NPY did not mediate either oedema formation, even when investigated in the presence of the vasodilator calcitonin gene-related peptide (CGRP), or neutrophil accumulation in murine skin. 6. We conclude that the major vasoactive activity of NPY in the cutaneous microvasculature is to act in a potent manner to decrease blood flow via Y1 receptors, with evidence for the additional involvement of postjunctional Y2 receptors. Our results do not provide evidence for a potent proinflammatory activity of NPY in the cutaneous microvasculature.

Neuroeffector mechanisms involved in the regulation of dog splenic arterial tone

It has been recognized that sympathetic neurons release several transmitters but mainly adenosine 5'-triphosphate (ATP), noradrenaline, and neuropeptide Y (NPY). Recently, we reported that periarterial nerve electrical stimulation (PNS) produced biphasic vasoconstrictions consisting of an initial transient, predominantly P2X-purinoceptor-mediated constriction followed by a prolonged, alpha(1)-adrenoceptor-mediated one in canine isolated splenic arteries. In this article, we tried to analyze the effects of several selective key drugs that influence the PNS-induced responses, and we functionally showed sympathetic transmitter releasing mechanisms by pharmacological analysis using purinergic, adrenergic, and NPYergic agonists and antagonists.

Semisynthesis and characterization of the first analogues of pro-neuropeptide y

Enzymatic cleavage of prohormone neuropeptide Y (proNPY) leads to mature neuropeptide Y (NPY), a widely distributed neuropeptide with multiple functions both peripherally and centrally. A single dibasic pair of amino acids, Lys38-Arg39, represents the recognition motif for a class of hormone-processing enzymes known as prohormone convertases (PCs). Two members of this PC family, PC1/3 and PC2, are involved in proNPY cleavage. The aim of this work was to establish an effective method for the generation of full-length 69-amino acid proNPY analogues for further studies of prohormone convertase interaction. We have chosen two ligation sites in order to perform the semisynthesis of proNPY analogues by expressed protein ligation (EPL). By using the intein-mediated purification system (IMPACT) with improved conditions for intein splicing, we were able to isolate proNPY 1-40 and proNPY 1-54 fragments as Cterminal thioesters. Peptides bearing Nterminal cysteine instead of the naturally occurring Ser41 and Thr55 residues, respectively, were generated by solid-phase peptide synthesis. Moreover, labels (carboxyfluorescein and biotin) were inserted into the peptide sequences. The synthesis of the [C41]proNPY 41-69 fragment, which proved to be a difficult peptide sequence, could be achieved by the incorporation of two pseudo-proline derivatives. Western blot analysis revealed that all five proNPY analogues are recognized by monoclonal antibodies directed against NPY as well as against the Cflanking peptide of NPY (CPON).

Pharmacological analysis of functional neurovascular transmission in canine splenic arteries: role of neuropeptide Y

1 The effects of neuropeptide Y (NPY) upon the isolated vasculature are reviewed. 2 The vasconstrictor responses to periarterial nerve stimulation (PNS) and neurotransmission by noradrenaline (NA) and ATP are discussed and illustrated using canine isolated perfused splenic artery. 3 Modulation of the vascular responses to PNS by NPY via pre- and post-junctional NPY Y2 and Y1 receptors is discussed. 4 Evidence is presented for different alpha1-adrenoceptor subtypes mediating vasoconstriction to exogenous and endogenously released NA and their different locations in the neurovascular junction and extrajunctional regions. 5 Activation of NPY Y1-receptors potentiates sympathetic nerve activated alpha1-adrenoceptor vasoconstriction. The proposal that the postjunctional alpha1B adrenoceptor may be linked to the NPY Y1-receptor and is responsible for co-operation between sympathetic and NPYergic interactions in the vasculature is discussed.