Low-variance RNAs identify Parkinson's disease molecular signature in blood.

The diagnosis of Parkinson's disease (PD) is usually not established until advanced neurodegeneration leads to clinically detectable symptoms. Previous blood PD transcriptome studies show low concordance, possibly resulting from the use of microarray technology, which has high measurement variation. The Leucine-rich repeat kinase 2 (LRRK2) G2019S mutation predisposes to PD. Using preclinical and clinical studies, we sought to develop a novel statistically motivated transcriptomic-based approach to identify a molecular signature in the blood of Ashkenazi Jewish PD patients, including LRRK2 mutation carriers. Using a digital gene expression platform to quantify 175 messenger RNA (mRNA) markers with low coefficients of variation (CV), we first compared whole-blood transcript levels in mouse models (1) overexpressing wild-type (WT) LRRK2, (2) overexpressing G2019S LRRK2, (3) lacking LRRK2 (knockout), and (4) and in WT controls. We then studied an Ashkenazi Jewish cohort of 34 symptomatic PD patients (both WT LRRK2 and G2019S LRRK2) and 32 asymptomatic controls. The expression profiles distinguished the four mouse groups with different genetic background. In patients, we detected significant differences in blood transcript levels both between individuals differing in LRRK2 genotype and between PD patients and controls. Discriminatory PD markers included genes associated with innate and adaptive immunity and inflammatory disease. Notably, gene expression patterns in levodopa-treated PD patients were significantly closer to those of healthy controls in a dose-dependent manner. We identify whole-blood mRNA signatures correlating with LRRK2 genotype and with PD disease state. This approach may provide insight into pathogenesis and a route to early disease detection.

The novel neuropeptide Y Y5 receptor antagonist Lu AA33810 [N-[[trans-4-[(4,5-dihydro[1]benzothiepino[5,4-d]thiazol-2-yl)amino]cyclohexyl]methyl]-methanesulfonamide] exerts anxiolytic- and antidepressant-like effects in rat models of stress sensitivity.

Neuropeptide Y (NPY) regulates physiological processes via receptor subtypes (Y(1), Y(2), Y(4), Y(5), and y(6)). The Y(5) receptor is well known for its role in appetite. Based on expression in the limbic system, we hypothesized that the Y(5) receptor might also modulate stress sensitivity. We identified a novel Y(5) receptor-selective antagonist, Lu AA33810 [N-[[trans-4-[(4,5-dihydro[1]-benzothiepino[5,4-d]thiazol-2-yl)amino]cyclohexyl]methyl]-methanesulfonamide], that bound to cloned rat Y(5) receptors (K(i) = 1.5 nM) and antagonized NPY-evoked cAMP and calcium mobilization in vitro. Lu AA33810 (3-30 mg/kg p.o.) blocked feeding elicited by intracerebroventricular injection of the Y(5) receptor-selective agonist [cPP(1-7),NPY(19-23),Ala(31),Aib(32),Gln(34)]-hPancreatic Polypeptide in Sprague-Dawley rats. In vivo effects of Lu AA33810 were correlated with brain exposure > or = 50 ng/g and ex vivo Y(5) receptor occupancy of 22 to 95%. Lu AA33810 was subsequently evaluated in models of stress sensitivity. In Fischer 344 rats, Lu AA33810 (30 mg/kg p.o.) attenuated increases in plasma ACTH and corticosterone elicited by intracerebroventricular injection of [cPP(1-7),NPY(19-23),Ala(31),Aib(32),Gln(34)]-hPancreatic Polypeptide. In Sprague-Dawley rats subjected to the social interaction test, Lu AA33810 (3-30 mg/kg p.o.) produced anxiolytic-like effects after acute or chronic treatment. In Flinders sensitive line rats, chronic dosing of Lu AA33810 (10 mg/kg/day i.p.) produced anxiolytic-like effects in the social interaction test, plus antidepressant-like effects in the forced swim test. In Wistar rats exposed to chronic mild stress, chronic dosing of Lu AA33810 (3 and 10 mg/kg/day i.p.) produced antidepressant-like activity, i.e., normalization of stress-induced decrease in sucrose consumption. We propose that Y(5) receptors may function as part of an endogenous stress-sensing system to mediate social anxiety and reward or motivational deficits in selected rodent models.

The MCH1 receptor antagonist SNAP 94847 induces sensitivity to dopamine D2/D3 receptor agonists in rats and mice.

Antidepressant treatment of two or more weeks in rats has been shown to enhance the locomotor-stimulating effects of dopamine D(2)/D(3) receptor agonists. This action has been attributed to an increased sensitivity of postsynaptic dopamine receptors in the nucleus accumbens, thought to represent an essential mechanism by which antidepressants act therapeutically to enhance reward and motivation. We tested whether the melanin-concentrating hormone receptor(1) (MCH(1)) antagonist SNAP 94847, reported to have antidepressant-like activity in several preclinical behavioral models, mimics this key feature of established antidepressants. Locomotor responses to the dopamine D(2)/D(3) agonist quinpirole following acute or chronic administration of fluoxetine (18 mg/kg/day) or SNAP 94847 (20 mg/kg/day) were assessed in habituated Sprague-Dawley rats, as well as BALB/c and CD-1 mice. Rats showed a significant increase in quinpirole-induced locomotor activity following chronic (2 weeks), but not acute (1 h) fluoxetine or SNAP 94847 administration. BALB/c mice treated for 21 days with fluoxetine or SNAP 94847 showed marked increases in quinpirole-induced locomotor activity, with the onset of hyper-locomotion appearing earlier in the time course after SNAP 94847 compared to fluoxetine. Administration of either compound for 7 days was also sufficient to augment the quinpirole response in BALB/c mice. Fluoxetine and SNAP 94847 (21 days) failed to modify quinpirole responses in CD-1 mice, and the compounds were ineffective after acute administration in both mouse strains. This report demonstrates in two rodent species that chronic treatment with an MCH(1) receptor antagonist, as with clinically proven antidepressants, produces sensitization to the locomotor effects of dopamine D(2)/D(3) agonists.

The effects of stressful stimuli and hypothalamic-pituitary-adrenal axis activation are reversed by the melanin-concentrating hormone 1 receptor antagonist SNAP 94847 in rodents.

Melanin-concentrating hormone (MCH) is an orexigenic and dipsogenic neuropeptide that has been reported to mediate acute behavioral and neuroendocrine stress-related responses via MCH(1) receptor activation in rodents. The purpose of the present investigation was to use the MCH(1) receptor antagonist SNAP 94847 (N-(3-{1-[4-(3,4-difluoro-phenoxy)-benzyl]-piperidin-4-yl}-4-methyl-phenyl)-isobutyramide) to determine the effects of MCH(1) receptor blockade on MCH-evoked adrenocorticotropic hormone (ACTH) release, chronic mild stress-induced anhedonia, stress-induced hyperthermia and forced swim stress-induced immobility. The appropriate dose range for testing SNAP 94847 was determined by measuring MCH-evoked water drinking. The corresponding occupancy of MCH(1) receptors in rat striatum was also measured across a broad dose range. Orally administered (p.o.) SNAP 94847 (1-10 mg/kg) corresponds to 30-60% occupancy at MCH(1) receptors and significantly blocks water drinking induced by the intracerebroventricular (i.c.v.) injection of MCH. MCH (i.c.v.) significantly elevates plasma levels of ACTH in rats, and SNAP 94847 (2.5 mg/kg, p.o.) blocks MCH-evoked ACTH release. Using the chronic mild stress paradigm, we show that repeated daily exposure to environmental stressors for 5 weeks significantly suppresses sucrose intake in rats, and that SNAP 94847 (1 mg/kg, BID) for 1-5 weeks restores baseline sucrose intake. Moreover, a single administration of SNAP 94847 attenuates stress-induced hyperthermia and the behavioral effects of forced swim stress with minimal effective doses of 2.5 and 30 mg/kg (p.o.), respectively. The regulation of ACTH release and reversal of the effects of chronic and acute stress by SNAP 94847 are suggestive of a role for MCH(1) receptor blockade in the treatment of disorders characterized by high allostatic load.

Anxiolytic- and antidepressant-like profiles of the galanin-3 receptor (Gal3) antagonists SNAP 37889 and SNAP 398299.

The neuropeptide galanin mediates its effects through the receptor subtypes Gal(1), Gal(2), and Gal(3) and has been implicated in anxiety- and depression-related behaviors. Nevertheless, the receptor subtypes relevant to these behaviors are not known because of the lack of available galanin-selective ligands. In this article, we use behavioral, neurochemical, and electrophysiological approaches to investigate the anxiolytic- and antidepressant-like effects of two potent small-molecule, Gal(3)-selective antagonists, SNAP 37889 and the more soluble analog SNAP 398299. Acute administration of SNAP 37889 or SNAP 398299 enhanced rat social interaction. Furthermore, acute SNAP 37889 was also shown to reduce guinea pig vocalizations after maternal separation, to attenuate stress-induced hyperthermia in mice, to increase punished drinking in rats, and to decrease immobility and increase swimming time during forced swim tests with rats. Moreover, SNAP 37889 increased the social interaction time after 14 days of treatment and maintained its antidepressant effects during forced swim tests with rats after 21 days of treatment. In microdialysis studies, SNAP 37889 partially antagonized the galanin-evoked reduction in hippocampal serotonin (5-hydroxytryptamine, 5-HT), as did the 5-HT(1A) receptor antagonist WAY100635. Their combination produced a complete reversal of the effect of galanin. SNAP 398299 partially reversed the galanin-evoked inhibition of dorsal raphe cell firing and galanin-evoked hyperpolarizing currents. These results indicate that Gal(3)-selective antagonists produce anxiolytic- and antidepressant-like effects, possibly by attenuating the inhibitory influence of galanin on 5-HT transmission at the level of the dorsal raphe nucleus.