29 research outputs found
Behavioural phenotypic characterization of CD-1 mice lacking the neuropeptide S receptor
Neuropeptide S (NPS) is the endogenous ligand of a previously orphan receptor now named NPSR. In the brain NPS regulates several biological functions including anxiety, arousal, locomotion, food intake, learning and memory, pain and drug abuse. Mice lacking the NPSR gene (NPSR(-/-)) represent an useful tool to investigate the neurobiology of the NPS/NPSR system. NPSR(-/-) mice have been generated in a 129S6/SvEv genetic background. In the present study we generated CD-1 congenic NPSR(+/+) and NPSR(-/-) mice and investigated their phenotype and sensitivity to NPS in various behavioural assays. The phenotype analysis revealed no locomotor differences between NPSR(+/+) and NPSR(-/-) mice. The behaviour of NPSR(+/+) and NPSR(-/-) mice in the righting reflex test was superimposable. No differences were recorded between the two genotypes in the elevated plus maze, open field and stress-induced hyperthermia tests, with the exception of rearing behaviour that was reduced in knockout animals. Moreover the behaviour of NPSR(+/+) and NPSR(-/-) mice in the forced swimming, novel object recognition and formalin assays was similar. The stimulatory effects of NPS in the locomotor activity test and its anxiolytic-like actions in the elevated plus maze and open field assays were evident in NPSR(+/+) but not NPSR(-/-) animals. In conclusion, the present study indicates that the NPS/NPSR system does not tonically control locomotion, sensitivity to diazepam, anxiety, depressive-like behaviours, memory and pain transmission in mice. Furthermore our results clearly show that the product of the NPSR gene represents the mandatory protein for all the NPS biological effects so far described
Altered anxiety-related behavior in nociceptin/orphanin FQ receptor gene knockout mice
Studies showed that nociceptin/orphanin FQ (N/OFQ) peptide receptor (NOP) agonists produce anxiolytic-like actions, while little is known about the effects of blockade of NOP receptor signaling in anxiety. To this aim, we investigated the behavioral phenotype of NOP receptor gene knockout mice (NOP(-/-)) in different assays. In the elevated plus-maze and light-dark box, NOP(-/-) mice displayed increased anxiety-related behavior. In the novelty-suppressed feeding behavior and elevated T-maze, NOP(-/-) mice showed anxiolytic-like phenotype, while no differences were found in the open-field, hole-board, marble-burying, and stress-induced hyperthermia. Altogether, these findings suggest that the N/OFQ-NOP receptor system modulates anxiety-related behavior in a complex manner
In Vitro and in Vivo Pharmacological Characterization of the Neuropeptide S Receptor Antagonist [d-Cys(tBu)5]Neuropeptide S
Neuropeptide S (NPS) was identified as the endogenous ligand of an orphan
receptor now referred to as the NPS receptor (NPSR). In the frame of a
structure-activity study performed on NPS Gly5, the NPSR ligand
[d-Cys(tBu)5]NPS was identified.
[d-Cys(tBu)5]NPS up to 100 ÎĽM did not stimulate
calcium mobilization in human embryonic kidney (HEK) 293 cells stably
expressing the mouse NPSR; however, in a concentration-dependent manner, the
peptide inhibited the stimulatory effects elicited by 10 and 100 nM NPS
(pKB, 6.62). In Schild analysis experiments
[d-Cys(tBu)5]NPS (0.1–100 μM) produced a
concentration-dependent and parallel rightward shift of the
concentration-response curve to NPS, showing a pA2 value
of 6.44. Ten micromolar [d-Cys(tBu)5]NPS did not affect
signaling at seven NPSR unrelated G-protein-coupled receptors. In the mouse
righting reflex (RR) recovery test, NPS given at 0.1 nmol i.c.v. reduced the
percentage of animals losing the RR in response to 15 mg/kg diazepam and their
sleeping time. [d-Cys(tBu)5]NPS (1–10 nmol) was
inactive per se but dose-dependently antagonized the arousal-promoting action
of NPS. Finally, NPSR-deficient mice were similarly sensitive to the hypnotic
effects of diazepam as their wild-type littermates. However, the
arousal-promoting action of 1 nmol NPS could be detected in wild-type but not
in mutant mice. In conclusion, [d-Cys(tBu)5]NPS behaves
both in vitro and in vivo as a pure and selective NPSR antagonist but with
moderate potency. Moreover, using this tool together with receptor knockout
mice studies, we demonstrated that the arousal-promoting action of NPS is
because of the selective activation of the NPSR protein
Pharmacological characterization of the nociceptin receptor mediating hyperalgesia in the mouse tail withdrawal assay
The newly discovered neuropeptide nociceptin (NC) has recently been reported to be the endogenous ligand of the opioid-like orphan receptor. Despite its structural similarity to opioids, when injected intracerebroventricularly (i.c.v.) in the mouse, NC exerts a direct hyperalgesic effect and reverses opioid-induced analgesia. In the present investigation, these two effects of NC were evaluated under the same experimental conditions; in addition, a pharmacological characterization of the receptor mediating these central effects of NC was attempted. 2. NC caused a dose dependent (0.1-10 nmol/mouse), naloxone-insensitive reduction of tail withdrawal latency with a maximal effect of about 50% of the reaction time observed in saline injected mice. In the same range of doses, NC inhibited morphine (1 nmol/mouse) induced analgesia. 3. The effects of the natural peptide were mimicked by NCNH2 and NC(1-13)NH2 (all tested at 1 nmol/mouse) while 1 nmol NC(1-9)NH2 was found to be inactive either in reducing tail withdrawal latency or in preventing morphine analgesia. 4. [Phe1psi(CH2-NH)Gly2]NC(1-13)NH2 ([F/G]NC(1-13)NH2), which has been shown to antagonize NC effects in the mouse vas deferens, acted as an agonist, mimicking NC effects in both the experimental paradigms. In addition, when NC and [F/G]NC(1-13)NH2 were given together, their effects were additive. 5. These results demonstrate that both the direct hyperalgesic action and the anti-morphine effect of NC can be studied under the same experimental conditions in the mouse tail withdrawal assay. Moreover, the pharmacological characterization of the NC functional site responsible for these actions compared with the peripherally active site, indicates the existence of important differences between peripheral and central NC receptors
Neuropeptides S is a stimulatory anxiolytic \u2013 a behavioral study in mice
Background and purpose. Neuropeptide S (NPS) was recently identified as the endogenous ligand of a previously orphan receptor now referred to as NPSR. In vivo, NPS produces a unique behavioral profile by increasing wakefulness and exerting anxiolytic-like effects. In the present study we further evaluated the in vivo effects of supraspinal NPS in mice.
Experimental approach. We assessed, in mice, the effects of intracerebroventricularly (i.c.v.) injected NPS on locomotor activity (LA), righting reflex (RR) recovery, and on anxiety states measured with the elevated plus maze (EPM) and stress induced hyperthermia (SIH) tests.
Key results. NPS (0.01 \u2013 1 nmol per mouse) caused a significant increase in LA in naive mice, in mice habituated to the test cages, and in animals sedated with diazepam 5 mg kg-1. In the RR assay, NPS dose dependently reduced the percent of animals losing the RR in response to diazepam 15 mg kg-1 and their sleeping time. In the EPM and SIH test, NPS dose dependently evokes anxiolytic-like effects by increasing the time (s) spent by animals in the open arms and reducing the stress-induced hyperthermic response, respectively.
Conclusions and Implications. We provide further evidence that NPS acts as a novel modulator of arousal and anxiety-related behaviors by promoting a unique pattern of effects: stimulation associated with anxiolysis. Therefore NPSR ligands may represent innovative drugs for the treatment of sleep and anxiety disorders
Endogenous nociceptin/orphanin FQ signalling produces opposite spinal antinociceptive and supraspinal pronociceptive effects in the mouse formalin test: Pharmacological and genetic evidences
Nociceptin/orphanin FQ (N/OFQ) has been demonstrated to modulate nociceptive transmission via selective activation of
N/OFQ peptide (NOP) receptors. Despite huge research efforts, the role(s) of the endogenous N/OFQ-NOP receptor system in pain
processing remains incompletely understood. In the present study, we investigated the role of endogenous N/OFQ in the processing of
tonic nociceptive input. To address this issue the effects of NOP-selective antagonists [Nphe1,Arg14,Lys15]N/OFQ-NH2 (UFP-101)
and J-113397 on nociceptive behaviour, and the nociceptive phenotype of NOP receptor-deficient mice were tested in the mouse formalin
test. Twenty microliters of 1.5% formalin solution was injected subcutaneously into the right hind paw causing a characteristic
pattern of nociceptive behaviours (licking, biting and lifting of the injected paw). In control mice, the injection of formalin resulted in a
classical biphasic nociceptive response with the first phase lasting from 0 to 10 min and the second phase from 15 to 45 min. UFP-101
at 10 nmol/mouse (but not at 1 nmol/mouse) produced antinociceptive action when injected intracerebroventricularly and a pronociceptive
action when given intrathecally. Systemic administration of J-113397 (10 mg/kg, intravenously) and the genetic ablation of
the NOP receptor gene both produced a significant increase of mouse nociceptive behaviour. Collectively, these results demonstrate
that endogenous N/OFQ-NOP receptor signalling is activated during the mouse formalin test producing spinal antinociceptive and
supraspinal pronociceptive effects. The overall effect of blocking NOP receptor signalling, by either systemic pharmacological
antagonism or genetic ablation, indicates that the spinal antinociceptive action prevails over supraspinal pronociceptive effects