Further studies on the pharmacological features of the nociceptin/orphanin FQ receptor ligand ZP120

Safety, Tolerability, and Antihypertensive Effect of SER100, an Opiate Receptor-Like 1 (ORL-1) Partial Agonist, in Patients With Isolated Systolic Hypertension

The purpose of the present trial was to evaluate safety, tolerability, and effect on systolic blood pressure (SBP) of SER100 in a small group of patients with isolated systolic hypertension (ISH) in treatment with at least 1 antihypertensive drug. Eligible patients were randomized to either SER100 (10 mg) or placebo in a crossover design, and 2 doses were given subcutaneously (SC), 8 hours apart, on 2 consecutive days. On all treatment days patients were monitored with an ambulatory blood pressure measurement device for 12 daytime hours. Seventeen patients completed treatment. There were no serious or severe adverse events. Relative to placebo SER100 induced an average reduction of SBP during the 2 treatment days of 7.0 mm Hg (P = 0.0032), whereas the average reduction of diastolic blood pressure (DBP) over the same period was 3.8 mm Hg (P = 0.0011). For patients with ISH, this short-term cross-over study of SC SER100 demonstrated an acceptable safety profile and consistent, significant lowering of SBP and DBP. As initial clinical proof of concept for a new class of drugs, a nociceptin agonist peptide, the results were encouraging and warrant further research.

Functional pharmacological characterization of SER100 in cardiovascular health and disease

BACKGROUND AND PURPOSE

SER100 is a selective nociceptin (NOP) receptor agonist with sodium-potassium-sparing aquaretic and anti-natriuretic activity. This study was designed to characterize the functional cardiovascular pharmacology of SER100 in vitro and in vivo, including experimental models of cardiovascular disease.

EXPERIMENTAL APPROACH

Haemodynamic, ECG parameters and heart rate variability (HRV) were determined using radiotelemetry in healthy, conscious mice. The haemodynamic and vascular effects of SER100 were also evaluated in two models of cardiovascular disease, spontaneously hypertensive rats (SHR) and murine hypoxia-induced pulmonary hypertension (PH). To elucidate mechanisms underlying the pharmacology of SER100, acute blood pressure recordings were performed in anaesthetized mice, and the reactivity of rodent aorta and mesenteric arteries in response to electrical- and agonist-stimulation assessed.

KEY RESULTS

SER100 caused NOP receptor-dependent reductions in mean arterial blood pressure and heart rate that were independent of NO. The hypotensive and vasorelaxant actions of SER100 were potentiated in SHR compared with Wistar Kyoto. Moreover, SER100 reduced several indices of disease severity in experimental PH. Analysis of HRV indicated that SER100 decreased the low/high frequency ratio, an indicator of sympatho-vagal balance, and in electrically stimulated mouse mesenteric arteries SER100 inhibited sympathetic-induced contractions.

CONCLUSIONS AND IMPLICATIONS

SER100 exerts a chronic hypotensive and bradycardic effects in rodents, including models of systemic and pulmonary hypertension. SER100 produces its cardiovascular effects, at least in part, by inhibition of cardiac and vascular sympathetic activity. SER100 may represent a novel therapeutic candidate in systemic and pulmonary hypertension.

Nociceptin Opioid Receptor (NOP) as a Therapeutic Target: Progress in Translation from Preclinical Research to Clinical Utility

In the two decades since the discovery of the nociceptin opioid receptor (NOP) and its ligand, nociceptin/orphaninFQ (N/OFQ), steady progress has been achieved in understanding the pharmacology of this fourth opioid receptor/peptide system, aided by genetic and pharmacologic approaches. This research spawned an explosion of small-molecule NOP receptor ligands from discovery programs in major pharmaceutical companies. NOP agonists have been investigated for their efficacy in preclinical models of anxiety, cough, substance abuse, pain (spinal and peripheral), and urinary incontinence, whereas NOP antagonists have been investigated for treatment of pain, depression, and motor symptoms in Parkinson's disease. Translation of preclinical findings into the clinic is guided by PET and receptor occupancy studies, particularly for NOP antagonists. Recent progress in preclinical NOP research suggests that NOP agonists may have clinical utility for pain treatment and substance abuse pharmacotherapy. This review discusses the progress toward validating the NOP-N/OFQ system as a therapeutic target.

Acute and chronic antiparkinsonian effects of the novel nociceptin/orphanin FQ receptor antagonist NiK-21273 in comparison with SB-612111

BACKGROUND AND PURPOSE

Nociceptin/orphanin FQ (N/OFQ) peptide (NOP) receptor antagonists have been proposed as a novel therapeutic approach to Parkinson's disease. Main limitations of previous studies were the use of structurally similar compounds and the evaluation of their acute effects only. We report here on the acute and long-term antiparkinsonian effects of the novel compound 2-[3-[4-(2-chloro-6-fluoro-phenyl)-piperidin-1-ylmethyl]-2-(morpholine-4-carbonyl)-indol-1-yl]-acetamide (NiK-21273) in comparison with the potent and selective NOP receptor antagonist SB-612111.

EXPERIMENTAL APPROACH

Basic pharmacological properties of NiK-21273 were studied in cell lines and isolated tissues (mouse and rat vas deferens). Antiparkinsonian effects were studied in reserpinized mice and 6-hydroxydopamine hemilesioned rats under both acute and chronic administration protocols.

KEY RESULTS

In vitro, NiK-21273 behaved as a potent (pA(2) 7.7) and selective NOP receptor antagonist. In vivo, it reduced hypokinesia in reserpinized mice at 0.1 and 1 but not 10 mg·kg(-1), whereas SB-612111 (0.01-1 mg·kg(-1)) provided a dose-dependent antiparkinsonian effect. NiK-21273 ameliorated motor performance in 6-hydroxydopamine hemilesioned rats at 0.5 and 5 but not 15 mg·kg(-1). SB-612111 replicated these effects in the 0.01-1 mg·kg(-1) range without loss of efficacy. Both antagonists synergized with L-DOPA at subthreshold doses. Chronic administration of NiK-21273 provided delayed improvement in baseline activity at 0.5 and 1.5 mg·kg(-1), although tolerance to the higher dose was observed. Conversely, SB-612111 (1 mg·kg(-1)) maintained its effects over time without modifying baseline activity.

CONCLUSIONS AND IMPLICATIONS

NOP receptor antagonists provide motor benefit in parkinsonism models although the 'therapeutic' window and long-term effects may vary between compounds.

Opioid system and Alzheimer's disease

The opioid system may be involved in the pathogenesis of AD, including cognitive impairment, hyperphosphorylated tau, Aβ production, and neuroinflammation. Opioid receptors influence the regulation of neurotransmitters such as acetylcholine, norepinephrine, GABA, glutamate, and serotonin which have been implicated in the pathogenesis of AD. Opioid system has a close relation with Aβ generation since dysfunction of opioid receptors retards the endocytosis and degradation of BACE1 and γ-secretase and upregulates BACE1 and γ-secretase, and subsequently, the production of Aβ. Conversely, activation of opioid receptors increases the endocytosis of BACE1 and γ-secretase and downregulates BACE1 and γ-secretase, limiting the production of Aβ. The dysfunction of opioid system (opioid receptors and opioid peptides) may contribute to hyperphosphorylation of tau and neuroinflammation, and accounts for the degeneration of cholinergic neurons and cognitive impairment. Thus, the opioid system is potentially related to AD pathology and may be a very attractive drug target for novel pharmacotherapies of AD.

Endogenous opiates and behavior: 2009

This paper is the 32nd consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2009 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).

UFP-112 a potent and long-lasting agonist selective for the Nociceptin/Orphanin FQ receptor

Nociceptin/orphanin FQ (N/OFQ) controls several biological functions via selective activation of the N/OFQ peptide receptor (NOP). [(pF)Phe(4) Aib(7) Arg(14) Lys(15) ]N/OFQ-NH(2) (UFP-112) is an NOP receptor ligand designed using a combination of several chemical modifications in the same peptide sequence that increase NOP receptor affinity/potency and/or reduce susceptibility to enzymatic degradation. In the present review article, we summarize data from the literature and present original findings on the in vitro and in vivo pharmacological features of UFP-112. Moreover, important biological actions and possible therapeutic indications of NOP receptor agonists are discussed based on the results obtained with UFP-112 and compared with other peptide and nonpeptide NOP receptor ligands.

Assessment of nociceptin/orphanin FQ and micro-opioid receptor mRNA in the human right atrium

BACKGROUND

The expression of micro (mu: MOP) and nociceptin/orphanin FQ (NOP) receptors in the human myocardium is controversial. In this polymerase chain reaction (PCR)-based study using human right atrial biopsies, we have (i) probed for mRNA encoding NOP receptor and its endogenous peptide precursor, ppN/OFQ, and mRNA encoding MOP and (ii) attempted to correlate expression with cardiac function.

METHODS

mRNA encoding MOP, NOP, and the precursor for NOP (ppN/OFQ) was assessed by quantitative real-time PCR (Q-PCR) using validated TaqMan primers and compared with a housekeeper (glyceraldehyde-3-phosphate dehydrogenase, GAPDH). Q-PCR data are expressed as the difference in cycle threshold (DeltaC(t)=C(tGene of interest)-C(tGAPDH): high value, low expression) and patients were grouped according to left ventricular ejection fraction (LVEF).

RESULTS

Forty patients were recruited; NOP, MOP, and ppN/OFQ mRNA were measured in 38, 29, and 10 patients, respectively. DeltaC(t) (median and range) values for NOP and MOP were 10.9 (7.8-13.7) and 16.0 (12.3-18.9), respectively, representing low expression of MOP and approximately 34-fold more NOP. MOP mRNA was not detected in seven samples and with DeltaC(t) values of approximately 20, ppN/OFQ was considered absent. When patients were grouped into normal (>50%) and impaired (<50%) LVEF, there was no difference between the groups for either NOP or MOP. In some patients, intraoperative LVEF was estimated using transoesophageal echocardiography, and there was no correlation with either NOP or MOP.

CONCLUSIONS

The human right atrium of patients with coronary artery disease and heart failure expresses mRNA encoding NOP and possibly low levels of MOP. This does not correlate with degree of cardiac dysfunction. In addition, the atrium does not express ppN/OFQ mRNA.