Hypothalamic CRF1 receptor mechanisms are not sufficient to account for binge-like palatable food consumption in female rats.

OBJECTIVE: The present study evaluated the effect of systemic injection of the CRF1 receptor antagonist R121919, the corticosterone synthesis inhibitor metyrapone and central amygdala (CeA) injections of the nonselective CRF antagonist D-Phe-CRF(12-41) in rats in which binge eating was evoked by stress and cycles of food restriction. METHOD: Female rats were subjected or not to repeated cycles of regular chow food restriction/ad libitum feeding during which they were also given limited access (2 h) to palatable food. On the test day, rats were either exposed or not to the sight of the palatable food for 15 min without allowing access, before assessing food consumption. RESULTS: Systemic injections of R121919, but not of the metyrapone, blocked binge-like eating behavior. Restricted and stressed rats showed up-regulation of crh1 receptor mRNA signal in the bed nucleus of the stria terminalis and CeA but not in basolateral amygdala (BLA) or in the paraventricular nucleus. Injection D-Phe-CRF(12-41) in CeA but not in the BLA-blocked binge-like eating behavior. DISCUSSION: These findings demonstrate that extra-hypothalamic CRF1 receptors, rather than those involved in endocrine functions, are involved in binge eating and the crucial role of CRF receptors in CeA. CRF1 receptor antagonism may represent a novel pharmacological treatment for binge-related eating disorders.

Role of bed nucleus of the stria terminalis corticotrophin-releasing factor receptors in frustration stress-induced binge-like palatable food consumption in female rats with a history of food restriction.

We developed recently a binge-eating model in which female rats with a history of intermittent food restriction show binge-like palatable food consumption after 15 min exposure to the sight of the palatable food. This "frustration stress" manipulation also activates the hypothalamic-pituitary-adrenal stress axis. Here, we determined the role of the stress neurohormone corticotropin-releasing factor (CRF) in stress-induced binge eating in our model. We also assessed the role of CRF receptors in the bed nucleus of the stria terminalis (BNST), a brain region implicated in stress responses and stress-induced drug seeking, in stress-induced binge eating. We used four groups that were first exposed or not exposed to repeated intermittent cycles of regular chow food restriction during which they were also given intermittent access to high-caloric palatable food. On the test day, we either exposed or did not expose the rats to the sight of the palatable food for 15 min (frustration stress) before assessing food consumption for 2 h. We found that systemic injections of the CRF1 receptor antagonist R121919 (2,5-dimethyl-3-(6-dimethyl-4-methylpyridin-3-yl)-7 dipropylamino pyrazolo[1,5-a]pyrimidine) (10-20 mg/kg) and BNST (25-50 ng/side) or ventricular (1000 ng) injections of the nonselective CRF receptor antagonist D-Phe-CRF(12-41) decreased frustration stress-induced binge eating in rats with a history of food restriction. Frustration stress also increased Fos (a neuronal activity marker) expression in ventral and dorsal BNST. Results demonstrate a critical role of CRF receptors in BNST in stress-induced binge eating in our rat model. CRF1 receptor antagonists may represent a novel pharmacological treatment for bingeing-related eating disorders.

Caloric restriction increases the sensitivity to the hyperphagic effect of nociceptin/orphanin FQ limiting its ability to reduce binge eating in female rats.

RATIONALE: Nociceptin/orphanin FQ (N/OFQ) is a functional antagonist of corticotrophin-releasing factor, the main mediator of the stress response. Stress represents a key determinant of binge eating (BE) for highly palatable food (HPF). OBJECTIVES: In relation to the antistress properties of N/OFQ, we evaluated its effect on BE. After the observation that episodes of food restriction increase the sensitivity to its hyperphagic effects, the function of NOP receptor and N/OFQ was investigated after cycles of food restrictions. MATERIALS AND METHODS: In BE experiments, four groups were used: rats fed normally and not stressed or stressed, rats exposed to cycles of restriction/refeeding and then stressed, or not stressed. In the other experiments, two groups were used: rats exposed or not to food restriction. RESULTS: Only restricted and stressed rats exhibited BE for HPF (containing chocolate cream). Intracerebroventricular injections of N/OFQ of 0.5 nmol/rat significantly reduced BE. N/OFQ 1 nmol/rat did not reduce BE but significantly increased HPF intake following food restrictions. Cycles of food restriction increased animals' sensitivity to the hyperphagic effect of N/OFQ for HPF. In situ hybridization studies following food restrictions showed decreased ppN/OFQ mRNA expression in the bed nucleus of the stria terminalis and increased expression of ppN/OFQ and NOP receptor mRNA in the ventral tegmental area and in the ventromedial hypothalamus, respectively. CONCLUSIONS: These findings indicate that N/OFQ slightly reduces BE at low doses, while higher doses increase HPF intake, due to increased sensitivity to its hyperphagic effect following a history of caloric restrictions.

Reduced limbic metabolism and fronto-cortical volume in rats vulnerable to alcohol addiction.

Alcohol abuse is associated with long-term reductions in fronto-cortical volume and limbic metabolism. However, an unanswered question in alcohol research is whether these alterations are the sole consequence of chronic alcohol use, or contain heritable contributions reflecting biological propensity toward ethanol addiction. Animal models of genetic predisposition to alcohol dependence can be used to investigate the role of inborn brain abnormalities in the aetiology of alcoholism. Here we used magnetic resonance imaging (MRI) in the Marchigian-Sardinian (msP) alcohol-preferring rats to assess the presence of inherited structural or functional brain alterations. Alcohol-naïve msP (N=22) and control rats (N=26) were subjected to basal cerebral blood volume (bCBV) mapping followed by voxel-based morphometry (VBM) of grey matter and tract-based spatial statistics mapping of white matter fractional anisotropy. msP rats exhibited significantly reduced bCBV, an established marker of resting brain function, in focal cortico-limbic and thalamic areas, together with reduced grey matter volume in the thalamus, ventral tegmental area, insular and cingulate cortex. No statistically significant differences in fractional anisotropy were observed between groups. These findings highlight the presence of inborn grey matter and metabolic abnormalities in alcohol-naïve msP rats, the localization and sign of which are remarkably similar to those mapped in abstinent alcoholics and subjects at high risk for alcohol dependence. Collectively, these results point for a significant role of heritable neurofunctional brain alterations in biological propensity toward ethanol addiction, and support the translational use of advanced imaging methods to describe the circuital determinants of vulnerability to drug addiction.

Effect of Hypericum perforatum Extract in an Experimental Model of Binge Eating in Female Rats.

Purpose. The present study evaluated the effect of Hypericum perforatum dry extract in an experimental model of binge eating (BE). Methods. BE for highly palatable food (HPF) was evoked in female rats by three 8-day cycles of food restriction/re-feeding and acute stress on the test day (day 25). Stress was induced by preventing access to HPF for 15 min, while rats were able to see and smell it. Hypericum perforatum dry extract was given by gavage. Results. Only rats exposed to both food restrictions and stress exhibited BE. The doses of 250 and 500 mg/kg of Hypericum perforatum extract significantly reduced the BE episode, while 125 mg/kg was ineffective. The same doses did not affect HPF intake in the absence of BE. The dose of 250 mg/kg did not significantly modify stress-induced increase in serum corticosterone levels, suggesting that the effect on BE is not due to suppression of the stress response The combined administration of 125 mg/kg of Hypericum perforatum together with Salidroside, active principle of Rhodiola rosea, produced a synergic effect on BE. Conclusions. The present results indicate for the first time that Hypericum perforatum extracts may have therapeutic properties in bingeing-related eating disorders.

A2A adenosine receptor agonists reduce both high-palatability and low-palatability food intake in female rats.

The present study examined the effect of two A(2A) adenosine receptor (AR) agonists, CGS 21680 and VT 7, on high-palatability food (HPF) intake in a model of binge eating in sated rats and on low-palatability food (LPF) intake in food-deprived rats. Binge eating was induced in female rats by three 8-day cycles of food restriction/refeeding, followed by acute stress. Two groups of rats were used: NR+NS rats normally fed and not stressed and R+S rats exposed to cycles of food restriction/refeeding and then stressed. R+S rats had higher intake of HPF than the NR+NS controls. The two A(2A)AR agonists were tested at doses of 0.1 and 0.05 mg/kg intraperitoneally; VT 7 did not modify locomotor activity at either dose, whereas CGS 21680 only slightly reduced it at the higher dose tested. The injection of 0.1 mg/kg of both agonists markedly reduced HPF intake both in R+S and in NR+NS rats. The dose of 0.05 mg/kg was inactive. CGS 21680 and VT 7, 0.1 mg/kg, also reduced the standard LPF intake in 24 h food-deprived rats; however, they did not reduce water intake, indicating that their effect on food intake is selective. The dose of 0.05 mg/kg was inactive. Thus, A(2A)AR agonists exert a rather general effect on food intake, inhibiting both HPF intake in sated rats and LPF intake in food-deprived rats. They may potentially be useful pharmacological agents to control binge-related eating disorders and to reduce food overconsumption associated with obesity.

Role of orexin-1 receptor mechanisms on compulsive food consumption in a model of binge eating in female rats.

Orexins (OX) and their receptors (OXR) modulate feeding, arousal, stress, and drug abuse. Neural systems that motivate and reinforce drug abuse may also underlie compulsive food seeking and intake. Therefore, the effects of GSK1059865 (5-bromo-N-[(2S,5S)-1-(3-fluoro-2-methoxybenzoyl)-5-methylpiperidin-2-yl]methyl-pyridin-2-amine), a selective OX(1)R antagonist, JNJ-10397049 (N-(2,4-dibromophenyl)-N'-[(4S,5S)-2,2-dimethyl-4-phenyl-1,3-dioxan-5-yl]urea), a selective OX(2)R antagonist, and SB-649868 (N-[((2S)-1-{[5-(4-fluorophenyl)-2-methyl-1,3-thiazol-4-yl]carbonyl}-2-piperidinyl)methyl]-1-benzofuran-4-carboxamide), a dual OX(1)/OX(2)R antagonist were evaluated in a binge eating (BE) model in female rats. BE of highly palatable food (HPF) was evoked by three cycles of food restriction followed by stress, elicited by exposing rats to HPF, but preventing them from having access to it for 15 min. Pharmacokinetic assessments of all compounds were obtained under the same experimental conditions used for the behavioral experiments. Topiramate was used as the reference compound as it selectively blocks BE in rats and humans. Dose-related thresholds for sleep-inducing effects of the OXR antagonists were measured using polysomnography in parallel experiments. SB-649868 and GSK1059865, but not JNJ-10397049, selectively reduced BE for HPF without affecting standard food pellet intake, at doses that did not induce sleep. These results indicate, for the first time, a major role of OX(1)R mechanisms in BE, suggesting that selective antagonism at OX(1)R could represent a novel pharmacological treatment for BE and possibly other eating disorders with a compulsive component.

Effects of A2A adenosine receptor blockade or stimulation on alcohol intake in alcohol-preferring rats.

RATIONALE: A(2A) adenosine receptors (A(2A)ARs) have been proposed to be involved in drug addiction; however, preclinical studies about the effects of A(2A)AR ligands on alcohol consumption have provided inconsistent results. OBJECTIVES: The present study evaluated the effect of intraperitoneal injections of the A(2A)AR antagonist ANR 94, and the A(2A)AR agonists CGS 21680 and VT 7 on voluntary drinking and operant self-administration of 10% ethanol in Marchigian Sardinian alcohol-preferring (msP) rats. RESULTS: Voluntary ethanol drinking was increased by ANR 94 in acute and subchronic experiments, while it was reduced by A(2A)AR agonists. The effect of CGS 21680 was abolished by a low dose of ANR 94, confirming its mediation by A(2A)ARs. Ethanol self-administration was reduced by CGS 21680 and VT 7, while ANR 94 slightly but significantly increased it. Blood alcohol levels were not modified by A(2A)AR agonists, indicating that their effect is not related to ethanol pharmacokinetics. The effect of VT 7 on ethanol drinking was behaviourally selective; ethanol and food intake were reduced, but water intake was increased, and total fluid intake was not different from that of controls. Moreover, VT 7 did not affect locomotor activity. CGS 21680 (0.1 mg/kg) did not modify total fluid intake, but 0.2 and 0.3 mg/kg reduced total fluid intake and locomotor activity. CONCLUSION: These results provide evidence that A(2A)AR agonists reduce ethanol consumption in msP rats, which represent an animal model of alcohol abuse related to stress, anxiety and depression. A(2A)ARs may represent a potential target for treatment of alcohol abuse.

Commercially available lipid formulations of amphotericin b: are they bioequivalent and therapeutically equivalent?

Amphotericin B is a polyene macrolide derived from Streptomyces nodosus. Introduced into therapy in 1957, for decades amphotericin B has been the "gold standard" for fighting systemic fungal infections. In order to facilitate its systemic use, much attention has been paid to the development of pharmaceutical forms that could reduce its toxicity, especially for the kidney. Because of its low solubility in water and excellent solubility in lipids, amphotericin B is an ideal candidate for lipid-based formulations. Three different lipid formulations for intravenous infusion are currently commercially available: liposomal amphotericin (AmBisome), Amphotericin lipid complex (Abelcet) and Amphotericin colloidal dispersion (Amphocil). The three lipid formulations of amphotericin B show significantly different structural, physical, chemical, pharmacokinetic, pharmacodynamic and toxicological characteristics. Several lines of evidence indicate that the three formulations of amphotericin B are not therapeutically equivalent. First, they are not bioequivalent. Second, even though a complete picture of controlled clinical research designed to compare effectiveness and safety of the three lipid formulations is not available, all the clinical studies analyzed report clear differences in toxicity between the three formulations. AmBisome appears to be clearly less toxic than the other two formulations, in terms of nephrotoxicity and of incidence of infusion-related adverse events. Third, the therapeutic non-equivalence of the three lipid formulations of amphotericin B is further supported by statements of Conferences and Scientific Societies that in their recommendations have awarded different grading to the three lipid formulations. (www.actabiomedica.it).

Pregabalin reduces alcohol drinking and relapse to alcohol seeking in the rat.

RATIONALE: Pregabalin (Lyrica™) is a structural analogue of γ-aminobutyric acid (GABA) approved by FDA for partial epilepsy, neuropathic pain and recently generalized anxiety disorder. While the exact cellular mechanism of action of pregabalin is still unclear, evidence from several studies suggests that it reduces excitatory neurotransmitter release and postsynaptic excitability. OBJECTIVES: Based on these mechanisms we sought interesting to evaluate the effect of pregabalin on alcohol-abuse-related behaviours. MATERIALS AND METHODS: For this purpose, using genetically selected alcohol-preferring Marchigian Sardinian (msP) rats, we evaluated the effect of pregabalin on alcohol drinking and relapse to alcohol seeking elicited by environmental conditioning factors or stress. RESULTS: Our results showed that treatment with pregabalin (0, 10, 30 and 60 mg/kg) given orally selectively reduced home cage alcohol drinking in msP rat. This effect was confirmed in self-administration experiments where pregabalin (0, 10 and 30 mg/kg) significantly reduced operant responding for alcohol but not for food. Using alcohol reinstatement models we also found that pregabalin (0, 10 and 30 mg/kg) abolished seeking behaviour elicited by the pharmacological stressor yohimbine as well as cues predictive of alcohol availability. CONCLUSIONS: Results demonstrate that pregabalin may have potential in the treatment of alcohol addiction.

Role of nociceptin/orphanin FQ receptors in the decrease of mucosal mast cells caused by acute stress in the rat colon.

AIMS: Mucosal mast cells (MMC) are mediators of the stress responses in the gastrointestinal tract. We examined the effect of acute cold-restraint stress and of the neuropeptide nociceptin/orphanin FQ (N/OFQ), implicated in the modulation of stress responses, on MMC density in the rat colon. MAIN METHODS: Stress was induced by restraining the animals into individual cages at 3°C for 3h. N/OFQ and the selective N/OFQ peptide (NOP) receptor antagonist, UFP-101, were infused subcutaneously via Alzet osmotic minipumps. Segments of the distal colon were collected. MMCs were identified immunohistochemically with a monoclonal antibody to rat mast cell protease (RMCP) II and with a rabbit polyclonal antibody to CD117/c-kit receptor. KEY FINDINGS: Acute stress caused a decrease in the density of MMCs in the rat colonic mucosa. Short-term peripheral infusion of N/OFQ (0.1 to 10 µg/kg/h for 4h) caused a dose-related reduction of MMC density. Peak reduction occurred after the 4-h infusion of N/OFQ, 1 µg/kg/h. Reduction was maintained after the 52-h infusion period and declined following 7 and 14 days of infusion. The infusion of N/OFQ (1µg/kg/h for 4h) in rats exposed to acute stress caused a decrease in MMC density comparable to that obtained with the single treatments. UFP-101, at the doses of 1 and 10 µg/kg/h, which itself had no significant effect on MMC density, when concurrently infused in stress-exposed rats, abolished the stress-induced decrease of MMC density. SIGNIFICANCE: Present results indicate that the peripheral N/OFQ-NOP system is involved in stress-induced reduction of MMC density.

Gender differences in Nociceptin/Orphanin FQ-induced food intake in strains derived from rats prone (WOKW) and resistant (Dark Agouti) to metabolic syndrome: a possible involvement of the cocaine- and amphetamine-regulated transcript system.

Our previous study found that when injected with Nociceptin/Orphanin FQ (N/OFQ) into the brain, male Dark Agouti (DA) rats, which are resistant to metabolic syndrome, have greater hyperphagia than male Wistar Ottawa Karlsburg W (WOKW) animals, which are prone to this disease. We attributed this difference to the fact that these two strains have different cocaine-amphetamine regulated transcript peptide (Cart) gene sequences and expression. In order to address this hypothesis, the present work focused on sex differences and analyzed not only male but also female N/OFQ-induced (0.25 and 0.5 nmol/rat) food intake in terms of their Cart and N/OFQ receptor gene expression in the hypothalamic area. In N/OFQ-naive WOKW females, cart gene expression is extremely elevated compared to N/OFQ-naive WOKW males. When male and female WOKW littermates are stimulated with N/OFQ, the food intake of females is significantly lower than that of the males. Granted, the N/OFQ feeding behavior experiments were not performed on the animals measured for Cart gene expression, but nonetheless, the responses observed in littermates point to an interesting avenue for further inquiry.

Activation of nuclear PPARγ receptors by the antidiabetic agent pioglitazone suppresses alcohol drinking and relapse to alcohol seeking.

BACKGROUND: Pioglitazone and rosiglitazone belong to the class of thiazolidinediones (TZDs). They were first developed as antioxidants and then approved for the clinical treatment of insulin resistance and Type 2 diabetes. TZDs bind with high affinity and activate peroxisome proliferator-activated receptor-gamma (PPARγ) receptors, which in the brain are expressed both in neurons and in glia. METHODS: We evaluated the effect of PPARγ activation by TZDs on alcohol drinking, relapse-like behavior, and withdrawal in the rat. We also tested the effect of TZDs on alcohol and saccharin self-administration. RESULTS: We showed that activation of PPARγ receptors by pioglitazone (0, 10, and 30 mg/kg) and rosiglitazone (0, 10 and 30 mg/kg) given orally selectively reduced alcohol drinking. The effect was blocked by pretreatment with the selective PPARγ antagonist GW9662 (5 µg/rat) given into the lateral cerebroventricle, suggesting that this TZD's effect is mediated by PPARγ receptors in the central nervous system. Pioglitazone abolished reinstatement of alcohol seeking, a relapse-like behavior, induced by yohimbine, a pharmacologic stressor, but did not affect cue-induced relapse. In the self-administration experiments, pioglitazone reduced lever pressing for alcohol but not for saccharin. Finally, pioglitazone prevented the expression of somatic signs of alcohol withdrawal. CONCLUSIONS: These findings provide new information about the role of brain PPARγ receptors and identify pioglitazone as candidate treatments for alcoholism and possibly other addictions.

Long-term peripheral infusion of nociceptin/orphanin FQ promotes hyperplasia, activation and migration of mucosal mast cells in the rat gastric fundus.

The endogenous neuropeptide nociceptin/orphanin FQ (N/OFQ) modulates behavioral and gastrointestinal responses to stress. Mucosal mast cells (MMCs) are primary mediators of stress-related responses in the gastrointestinal tract. We investigated the influence of N/OFQ and of the N/OFQ peptide (NOP) receptor antagonist, UFP-101, on MMCs in the rat gastric fundus. N/OFQ was infused subcutaneously for 52 h at 0.1, 1 and 10 µg/kg/h and at 1 µg/kg/h for 4h, 52 h, 7 days and 14 days via Alzet osmotic minipumps. Density of MMCs and connective tissue mast cells (CTMCs) was assessed histochemically and immunohistochemically. Activation and location of MMCs were assessed by transmission electron microscopy. Contacts between MMCs and nerve elements were assessed by double immunofluorescence. N/OFQ (1 µg/kg/h) and UFP-101 (10 and 30 µg/kg/h) were infused subcutaneously in the absence and presence of acute cold-restraint stress and density of MMCs was assessed. Peripheral N/OFQ dose-dependently increased the density of MMCs, while not influencing CTMCs. The increasing effect was maintained up to 14 days following continuous infusion, while after termination of the 4-h infusion, the effect declined rapidly. The peptide promoted the activation of MMCs and their migration from the lamina propria toward the epithelial layer. The association between MMCs and nerve fibers was time-dependently down-regulated following N/OFQ infusion. The stress-induced hyperplasia of MMCs was not influenced by N/OFQ and abolished by UFP-101. UFP-101 alone was ineffective. The present results suggest that endogenous N/OFQ could be considered a potential component of the circuit neuropeptides-mast cells-stress.

Activation of brain NOP receptors attenuates acute and protracted alcohol withdrawal symptoms in the rat.

BACKGROUND: Alcohol withdrawal refers to a cluster of symptoms that may occur from suddenly ceasing the use of alcohol after chronic or prolonged ingestion. These symptoms make alcohol abstinence difficult and increase the risk of relapse in recovering alcoholics. In previous studies, we demonstrated that treatment with Nociceptin/orphanin FQ (N/OFQ) significantly reduces alcohol consumption and attenuates alcohol-seeking behavior induced by environmental conditioning factors or by stress in rats. In this study, we evaluated whether activation of brain NOP receptors may also attenuate alcohol withdrawal signs in rats. METHODS: For this purpose, animals were subjected to a 6-day chronic alcohol intoxication (by intragastric administration), and at 8, 10, and 12 hours following cessation of alcohol exposure, they were treated intracerebroventricularly (ICV) with N/OFQ (0.0, 1.0, and 3.0 µg/rat). Somatic withdrawal signs were scored after ICV treatment. In a subsequent experiment, to evaluate N/OFQ effects on alcohol withdrawal-induced anxiety, another group of rats was subjected to ethanol intoxication and after 1 week was tested for anxiety behavior in the elevated plus maze (EPM). In the last experiment, an additional group of rats was tested for anxiety elicited by acute ethanol intoxication (hangover anxiety). For this purpose, animals received an acute dose (3.0 g/kg) of 20% alcohol and 12 hour later were tested in the EPM following ICV N/OFQ (0.0, 1.0, and 2.0 µg/rat). RESULTS: Results showed that N/OFQ significantly reduced the expression of somatic withdrawal signs and reversed anxiety-like behaviors associated with both chronic and acute alcohol intoxication. N/OFQ did not affect anxiety scores in nondependent animals. CONCLUSIONS: These findings suggest that the N/OFQ-NOP receptor system may represent a promising target for the development of new treatments to ameliorate alcohol withdrawal symptoms.

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.

Neuropeptide S facilitates cue-induced relapse to cocaine seeking through activation of the hypothalamic hypocretin system.

Drug addiction is a chronic relapsing disorder characterized by compulsive drug seeking and use. Environmental conditioning factors are among the major determinants of relapse in abstinent cocaine users. Here we describe a role of the neuropeptide S (NPS) system in regulating relapse. In rats with a history of cocaine self-administration, presentation of stimuli predictive of drug availability reinstates drug seeking, triggering relapse. Intracerebroventricular (ICV) injection of NPS increased conditioned reinstatement of cocaine seeking, whereas peripheral administration of the NPS receptor antagonist SHA 68 reduced it. Manipulation of the NPS receptor system did not modify cocaine self-administration. We also found that ICV NPS administration activates c-Fos expression in hypocretin-1/orexin-A (Hcrt-1/Ox-A) immunoreactive neurons in the lateral hypothalamus (LH) and in the perifornical area (PeF). Of note, intra-LH and intra-PeF administration of NPS increased conditioned reinstatement of cocaine responding, an effect that was selectively blocked with the Hcrt-1/Ox-A receptor selective antagonist SB334867. Finally, results showed that intra-LH injection of the NPS antagonist [D-Cys(tBu) (5)]NPS blocked cue-induced cocaine seeking, indicating a role for this system in the pathophysiology of drug relapse.

Effect of salidroside, active principle of Rhodiola rosea extract, on binge eating.

Stress is a key determinant of binge eating (BE). Since Rhodiola rosea is known to modulate stress responses, its effect in a model of BE was investigated. BE for highly palatable food (HPF) was evoked in female rats by three 8-day cycles of food restriction/re-feeding (for 4days 66% of the usual chow intake; for 4days food ad libitum) and acute stress on the test day (day 25). R. rosea dry extract (3% rosavin, 3.12% salidroside) or its active principles were given by gavage 1h before access to HPF. Only rats exposed to both food restrictions and stress exhibited BE in the first 15-60min after the stressful procedure. R. rosea extract 10mg/kg significantly reduced and 20mg/kg abolished the BE episode. R. rosea extract 20mg/kg abolished also stress-induced increase in serum corticosterone levels. The R. rosea active principle salidroside, but not rosavin, at doses present in the extract, dose-dependently reduced or abolished BE for the period in which it was elicited. In conclusion results indicate that R. rosea extracts may have therapeutic properties in bingeing-related eating disorders and that salidroside is the active principle responsible for this effect.

Central nociceptin/orphanin FQ system elevates food consumption by both increasing energy intake and reducing aversive responsiveness.

Nociceptin/orphanin FQ (N/OFQ), the nociceptin opioid peptide (NOP) receptor ligand, increases feeding when injected centrally. Initial data suggest that N/OFQ blocks the development of a conditioned taste aversion (CTA). The current project further characterized the involvement of N/OFQ in the regulation of hunger vs. aversive responses in rats by employing behavioral, immunohistochemical, and real-time PCR methodology. We determined that the same low dose of the NOP antagonist [Nphe(1)]N/OFQ(1-13)NH(2) delivered via the lateral ventricle diminishes both N/OFQ- and deprivation-induced feeding. This anorexigenic effect did not stem from aversive consequences, as the antagonist did not cause the development of a CTA. When [Nphe(1)]N/OFQ(1-13)NH(2) was administered with LiCl, it moderately delayed extinction of the LiCl-induced CTA. Injection of LiCl + antagonist compared with LiCl alone generated an increase in c-Fos immunoreactivity in the central nucleus of the amygdala. The antagonist alone elevated Fos immunoreactivity in the paraventricular nucleus of the hypothalamus, nucleus of the solitary tract, and central nucleus of the amygdala. Hypothalamic NOP mRNA levels were decreased during energy intake restriction induced by aversion, as well as in non-CTA rats food-restricted to match CTA-reduced consumption. Brain stem NOP was upregulated only in aversion. Prepro-N/OFQ mRNA showed a trend toward upregulation in restricted rats (P = 0.068). We conclude that the N/OFQ system promotes feeding by affecting the need to replenish lacking calories and by reducing aversive responsiveness. It may belong to mechanisms that shift a balance between the drive to ingest energy and avoidance of potentially tainted food.

Peripheral infusion of nociceptin/orphanin FQ influences the response of rat gastric and colonic mucosa to repeated stress.

The 17-amino acid peptide nociceptin/orphanin FQ (N/OFQ) plays a role in the regulation of stress responses and of emotional disorders. The objective of this study is to evaluate whether long-term peripheral N/OFQ could dose- and time-dependently influence the responses to repeated cold-restraint stress on the rat gastric and colonic mucosa. Rats were exposed to cold-restraint stress for 3h per day for 1, 2 and 3 consecutive days. N/OFQ was administered at doses of 0.1, 1 and 10 microg/kg/h via Alzet osmotic minipumps. In the gastric fundus, N/OFQ exerted dose-dependent beneficial effects against acute and repeated stress but, after prolonged treatment, became damaging in non-stressed rats. In the distal colon, N/OFQ exerted a protective effect against damage by acute and repeated stress with no influence on epithelial integrity in non-stressed rats. In both regions, the peptide itself dose- and time-dependently reduced intraepithelial mucins. The reduction in mucin content caused by stress was effectively counteracted by N/OFQ, 0.1 microg/kg/h, in the distal colon only. N/OFQ did not modify basal mucosal cell proliferation. The peptide at 0.1 and 1 microg/kg/h had no influence while at 10 microg/kg/h abolished stress-induced increase in cell proliferation. The present results provide evidence that N/OFQ is implicated in the regulation of resting and stress-challenged mucosal integrity and activity of mucin-producing cells.