Orexin 1 receptor antagonists in compulsive behavior and anxiety: possible therapeutic use.

Fifteen years after the discovery of hypocretin/orexin a large body of evidence has been collected supporting its critical role in the modulation of several regulatory physiological functions. While reduced levels of hypocretin/orexin were initially associated with narcolepsy, increased levels have been linked in recent years to pathological states of hypervigilance and, in particular, to insomnia. The filing to FDA of the dual-activity orexin receptor antagonist (DORA) suvorexant for the indication of insomnia further corroborates the robustness of such evidences.

Clinical pharmacology of eating and not eating.

FDA approval of Belviq and Qsymia seems to suggest that novel pharmacological targets to modulate human abnormal eating behaviours are still to be identified. However, a renewed translational approach opens new avenues on eating disorders and female vulnerability, highlighting the role of our reward pathway in obesity and binge eating and leading to potential novel targets. Nevertheless, the 'food addiction' hypothesis is still causing much scientific debate.

Identification, biological characterization and pharmacophoric analysis of a new potent and selective NK1 receptor antagonist clinical candidate.

The last two decades have provided a large weight of preclinical data implicating the neurokinin-1 receptor (NK1) and its cognate ligand substance P (SP) in a broad range of both central and peripheral disease conditions. However, to date, only the NK1 receptor antagonist aprepitant has been approved as a therapeutic and this is to prevent chemotherapy-induced nausea & vomiting (CINV). The belief remained that the full therapeutic potential of NK1 receptor antagonists had yet to be realized; therefore clinical evidence that NK1 receptor antagonists may be effective in major depression disorder, resulted in a significant further investment in discovering novel CNS penetrant druggable NK1 receptor antagonists to address this condition.

Brain reinforcement system function is ghrelin dependent: studies in the rat using pharmacological fMRI and intracranial self-stimulation.

Ghrelin (GHR) is an orexigenic gut peptide that interacts with brain ghrelin receptors (GHR-Rs) to promote food intake. Recent research suggests that GHR acts as a modulator of motivated behavior, suggesting a direct influence of GHR on brain reinforcement circuits. In the present studies, we investigated the role of GHR and GHR-Rs in brain reinforcement function.

GSK1614343, a novel ghrelin receptor antagonist, produces an unexpected increase of food intake and body weight in rodents and dogs.

Ghrelin is a 28-amino-acid polypeptide expressed in the stomach and hypothalamus that stimulates GH secretion, increases food intake (FI) and promotes body weight (BW) gain most likely via activation of the growth hormone secretagogue receptor type 1a (GHSR1a). GSK1614343 is a novel selective and potent GHSR antagonist with no partial agonist properties, recently characterized as GH secretion inhibitor by Sabbatini et al. [Chem Med Chem 2010;5:1450-1455].

Discovery and biological characterization of (2R,4S)-1'-acetyl-N-{(1R)-1-[3,5-bis(trifluoromethyl)phenyl]ethyl}-2-(4-fluoro-2-methylphenyl)-N-methyl-4,4'-bipiperidine-1-carboxamide as a new potent and selective neurokinin 1 (NK1) receptor antagonist clinical candidate.

A large body of compelling preclinical evidence supports the clinical use of neurokinin (NK) receptor antagonists in a plethora of CNS and non-CNS therapeutic areas. The significant investment made in this area over the past 2 decades culminated with the observation that NK(1) receptor antagonists elicited clinical efficacy in major depression disorders. In addition, aprepitant (Merck) was launched as a new drug able to prevent chemotherapy-induced nausea and vomiting (CINV).

Synthesis and pharmacological characterization of constrained analogues of Vestipitant as in vitro potent and orally active NK(1) receptor antagonists.

A focused exploration targeting conformationally restricted analogues of Vestipitant, resulted in the discovery of novel, in vitro potent NK(1) antagonists. In particular, two of the compounds reported exhibited a good pharmacokinetic (PK) profile and produced anxiolytic-like effects in the gerbil foot tapping (GFT) in vivo model.

Pre-exposure to environmental cues predictive of food availability elicits hypothalamic-pituitary-adrenal axis activation and increases operant responding for food in female rats.

The present study was undertaken to develop an animal model exploiting food cue-induced increased motivation to obtain food under operant self-administration conditions. To demonstrate the predictive validity of the model, rimonabant, fluoxetine, sibutramine and topiramate, administered 1 hour before the experiment, were tested. For 5 days, female Wistar rats were trained to self-administer standard 45 mg food pellets in one daily session (30 minutes) under FR1 (fixed ratio 1) schedule of reinforcement.

Discovery process and pharmacological characterization of 2-(S)-(4-fluoro-2-methylphenyl)piperazine-1-carboxylic acid [1-(R)-(3,5-bis-trifluoromethylphenyl)ethyl]methylamide (vestipitant) as a potent, selective, and orally active NK1 receptor antagonist.

In an effort to discover novel druglike NK(1) receptor antagonists a new series of suitably substituted C-phenylpiperazine derivatives was identified by an appropriate chemical exploration of related N-phenylpiperazine analogues, with the specific aim to maximize their in vitro affinity and optimize in parallel their pharmacokinetic profile. Among the compounds synthesized, 2-(S)-(4-fluoro-2-methylphenyl)piperazine-1-carboxylic acid [1-(R)-(3,5-bis-trifluoromethylphenyl)ethyl]methylamide (vestipitant) was identified as one of the most in vitro potent and selective NK(1) receptor antagonists ever discovered, showing appropriate pharmacokinetic properties and in vivo activity. On the basis of its preclinical profile, this compound was selected as a drug candidate.

Delay of ejaculation induced by SB-277011, a selective dopamine D3 receptor antagonist, in the rat.

Introduction: Dopamine (DA) plays a key role in different aspects of the male sexual response, including sexual motivation and arousal, penile erection, and ejaculation. The modalities of action of DA are however unclear, although the various DA receptors may differentially mediate the activity of DA in different aspects of the male sexual response.

Aim: To clarify the role of DA D(3) receptors in the control of the male sexual response.

A preclinical model of binge eating elicited by yo-yo dieting and stressful exposure to food: effect of sibutramine, fluoxetine, topiramate, and midazolam.

Rationale: Preclinical models are needed to investigate the neurobiology and psychobiology of binge eating and to identify innovative pharmacotherapeutic strategies.

Objectives: A modification of the model based on the combination of cyclic caloric restrictions and acute stress was developed to further increase its face validity and reliability and, for the first time, to assess its predictive value.

Materials And Methods: Four groups of female rats were employed: group 1 was normally fed and not stressed on the test day (25th); group 2 was fed normally but was exposed to an acute stress on day 25; group 3 was exposed to three cycles (4 days 66% of chow intake + 4 days food ad libitum) of yo-yo dieting but not stressed; and group 4 was exposed to cyclic yo-yo dieting and then stressed.

Systemic administration of ghrelin increases extracellular dopamine in the shell but not the core subdivision of the nucleus accumbens.

The gut-hormone ghrelin endogenously binds to the ghrelin receptor (GHS-R) to promote foraging and feeding behaviours mainly via the hypothalamic arcuate nucleus (ARC). GHS-Rs are also expressed in midbrain dopaminergic neurons of the ventral tegmental area (VTA) suggesting that ghrelin may modulate the mesolimbic dopamine (DA) system. In support of this hypothesis, previous results have shown that intraventricular administration of ghrelin in rats increases DA levels in the nucleus accumbens (NAc).

Correlation between serum ghrelin levels and cocaine-seeking behaviour triggered by cocaine-associated conditioned stimuli in rats.

Ghrelin is a brain-gut peptide with growth hormone-releasing and appetite-inducing activities. A growing body of evidence suggests that ghrelin may affect the central reward system and modulate the activity of the mesolimbic system. Recent clinical studies also showed a significant positive correlation between plasma ghrelin levels and craving in alcoholics.

Characterisation of the selective 5-HT1B receptor antagonist SB-616234-A (1-[6-(cis-3,5-dimethylpiperazin-1-yl)-2,3-dihydro-5-methoxyindol-1-yl]-1-[2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl)biphenyl-4-yl]methanone hydrochloride): in vivo neurochemical and behavioural evidence of anxiolytic/antidepressant activity.

The 5-HT1B receptor has attracted significant interest as a potential target for the development of therapeutics for the treatment of affective disorders such as anxiety and depression. Here we present the in vivo characterisation of a novel, selective and orally bioavailable 5-HT1B receptor antagonist, SB-616234-A (1-[6-(cis-3,5-dimethylpiperazin-1-yl)-2,3-dihydro-5-methoxyindol-1-yl]-1-[2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl)biphenyl-4-yl]methanone hydrochloride). SB-616234-A reversed the 5-HT1/7 receptor agonist, SKF-99101H-induced hypothermia in guinea pigs in a dose related manner with an ED50 of 2.

Down-regulation of amygdala preprotachykinin A mRNA but not 3H-SP receptor binding sites in subjects affected by mood disorders and schizophrenia.

Increasing evidence suggests that substance P (SP) neurokinin-1 (NK1) receptors are involved in stress and emotional responses, representing a potential target for the treatment of anxiety and depression in humans. Given the important role of the amygdaloid complex in the regulation of emotional behavior, we examined the mRNA levels of preprotachykinin A [PPT-A, a precursor of both SP and neurokinin A (NKA)] and 3H-SP binding sites in the amygdala of patients affected by bipolar disorder, major depression or schizophrenia as compared with matched control individuals. By means of in situ hybridization, a significant reduction of PPT-A mRNA expression levels was detected in the three diagnostic groups, mainly in the basal, lateral and accessory basal amygdaloid nuclei, but not in the temporal cortical area proximal to the amygdala.

SB-656104-A, a novel selective 5-HT7 receptor antagonist, modulates REM sleep in rats.

1 (6-((R)-2-[2-[4-(4-Chloro-phenoxy)-piperidin-1-yl]-ethyl]-pyrrolidine-1-sulphonyl)-1H-indole hydrochloride) (SB-656104-A), a novel 5-hydroxytryptamine (5-HT(7)) receptor antagonist, potently inhibited [(3)H]-SB-269970 binding to the human cloned 5-HT(7(a)) (pK(i) 8.7+/-0.1) and 5-HT(7(b)) (pK(i) 8.

Neurokinin 1 receptor and relative abundance of the short and long isoforms in the human brain.

Substance P exerts its various biochemical effects mainly via interactions through neurokinin-1 receptors (NK1). Recently, the NK1 receptor has attracted considerable interest for its possible role in a variety of psychiatric disorders including depression and anxiety. However, little is known regarding the anatomical distribution of NK1 in the human central nervous system (CNS).