Effects of opioid receptor ligands in rats trained to discriminate 22 from 2 hours of food deprivation suggest a lack of opioid involvement in eating for hunger.

It is well accepted that opioids promote feeding for reward. Some studies suggest a potential involvement in hunger-driven intake, but they suffer from the scarcity of methodologies differentiating between factors that intersect eating for pleasure versus energy. Here, we used a unique food deprivation discrimination paradigm to test a hypothesis that, since opioids appear to control feeding reward, injection of opioid agonists would not produce effects akin to 22 h of food deprivation.

Nociceptin/orphanin FQ receptors modulate the discriminative stimulus effects of oxycodone in C57BL/6 mice.

Background: Nociceptin/orphanin FQ (NOP) receptor ligands have shown efficacy as putative analgesics and can modulate the abuse-related effects of opioids, suggesting therapeutic applications. The discriminative stimulus effects of a drug are related to their subjective effects, a predictor of abuse potential. To determine whether activation of NOP receptors could alter the subjective effects of an abused opioid analgesic, a novel oxycodone discrimination was established in mice, characterized with positive and negative controls, and its expression evaluated with a NOP receptor agonist.

Effects of Acute and Repeated Administration of Oxycodone and Naloxone-Precipitated Withdrawal on Intracranial Self-Stimulation in Rats.

Incidence of prescription opioid abuse and overdose, often led by oxycodone, continues to increase, producing twice as many overdose deaths as heroin. Surprisingly, preclinical reports relevant to oxycodone's abuse-related effects are relatively sparse considering its history and patient usage. The goal of this study was to characterize dose- and time-dependent effects of acute and repeated oxycodone administration in a frequency-rate intracranial self-stimulation (ICSS) procedure, an assay often predictive of drug-related reinforcing effects, in male Sprague-Dawley rats.

Effects of acute and repeated dosing of the synthetic cannabinoid CP55,940 on intracranial self-stimulation in mice.

Background: Synthetic cannabinoids have emerged as a significant public health concern. To increase the knowledge of how these molecules interact on brain reward processes, we investigated the effects of CP55,940, a high efficacy synthetic CB1 receptor agonist, in a frequency-rate intracranial self-stimulation (ICSS) procedure.

Methods: The impact of acute and repeated administration (seven days) of CP55,940 on operant responding for electrical brain stimulation of the medial forebrain bundle was investigated in C57BL/6J mice.

Δ9-tetrahydrocannabinol and endocannabinoid degradative enzyme inhibitors attenuate intracranial self-stimulation in mice.

A growing body of evidence implicates endogenous cannabinoids as modulators of the mesolimbic dopamine system and motivated behavior. Paradoxically, the reinforcing effects of Δ(9)-tetrahydrocannabinol (THC), the primary psychoactive constituent of cannabis, have been difficult to detect in preclinical rodent models. In this study, we investigated the impact of THC and inhibitors of the endocannabinoid hydrolytic enzymes fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) on operant responding for electrical stimulation of the medial forebrain bundle [intracranial self-stimulation (ICSS)], which is known to activate the mesolimbic dopamine system.

Inhalation exposure to smoke from synthetic "marijuana" produces potent cannabimimetic effects in mice.

Background: Use of synthetic "marijuana" has increased in recent years, produced adverse effects and prompted the temporary DEA ban of five specific cannabinoid analogs, including JWH-018. The objectives of the current study include determining the chemical content of the herbal product, Buzz, assessing its behavioral effects upon inhalation exposure to mice, determining whether CB(1) receptors mediate its pharmacological activity, and ascertaining its biodisposition in blood and various organs.

Methods: Using a nose-only exposure system, mice were exposed to smoke produced from combustion of an herbal incense product, Buzz, which contained 5.

Discriminative stimulus properties of N-desmethylclozapine, the major active metabolite of the atypical antipsychotic clozapine, in C57BL/6 mice.

N-desmethylclozapine (NDMC) is the major active metabolite of the atypical antipsychotic drug clozapine and may contribute to the therapeutic efficacy of clozapine. Although they share many pharmacological features, it is noteworthy that NDMC is a partial dopamine D2 and cholinergic muscarinic M1/M4 agonist, whereas clozapine is a weak dopamine D2 receptor inverse agonist/antagonist and a nonselective muscarinic antagonist. To better understand the in-vivo pharmacological mechanisms of these drugs, male C57BL/6NHsd-wild-type mice were trained to discriminate 10.

Determination of naphthalen-1-yl-(1-pentylindol-3-yl)methanone (JWH-018) in mouse blood and tissue after inhalation exposure to 'buzz' smoke by HPLC/MS/MS.

The disposition of the cannabimimetic naphthalen-1-yl-(1-pentylindol-3-yl)methanone (JWH-018) in mice following inhalation of the smoke of the herbal incense product (HIP) 'Buzz' is presented. A high-pressure liquid chromatography with electrospray ionization triple quadrupole mass spectrometer (HPLC/MS/MS) method was validated for the analysis of JWH-018 in the specimens using deuterated Δ(9) -tetrahydrocannabinol (d(3) -THC) as the internal standard. JWH-018 was isolated by cold acetonitrile liquid-liquid extraction.

Detection and disposition of JWH-018 and JWH-073 in mice after exposure to "Magic Gold" smoke.

The disposition in mice of the cannabimimetics JWH-018 and JWH-073 in blood and brain following inhalation of the smoke from the herbal incense product (HIP) "Magic Gold" containing 3.6% JWH-018, 5.7% JWH-073 and less than 0.

The metabolites N-desmethylclozapine and N-desmethylolanzapine produce cross-tolerance to the discriminative stimulus of the atypical antipsychotic clozapine in C57BL/6 mice.

It has been previously shown that cross-tolerance to the discriminative stimulus properties of clozapine can be demonstrated with the drug discrimination paradigm. This study examined the ability of N-desmethylclozapine and N-desmethylolanzapine (metabolites of the atypical antipsychotic drugs clozapine and olanzapine, respectively) to induce cross-tolerance to the discriminative stimulus effects of clozapine. After C57BL/6 mice were trained to reliably discriminate 2.

delta(9)-Tetrahydrocannabinol-dependent mice undergoing withdrawal display impaired spatial memory.

Rationale: Cannabis users display a constellation of withdrawal symptoms upon drug discontinuation, including sleep disturbances, irritability, and possibly memory deficits. In cannabinoid-dependent rodents, the CB(1) antagonist rimonabant precipitates somatic withdrawal and enhances forskolin-stimulated adenylyl cyclase activity in cerebellum, an effect opposite that of acutely administered ∆(9)-tetrahydrocannabinol (THC), the primary constituent in cannabis.

Objectives: Here, we tested whether THC-dependent mice undergoing rimonabant-precipitated withdrawal display short-term spatial memory deficits, as assessed in the Morris water maze.

Marijuana dependence: not just smoke and mirrors.

Marijuana (Cannabis sativa) is the most commonly used illicit drug worldwide as well as in the Unites States. Prolonged use of marijuana or repeated administration of its primary psychoactive constituent, Δ9-tetrahydrocannabinol (THC), can lead to physical dependence in humans and laboratory animals. The changes that occur with repeated cannabis use include alterations in behavioral, physiological, and biochemical responses.

Clozapine and N-methyl-D-aspartate have positive modulatory actions on their respective discriminative stimulus properties in C57BL/6 mice.

The impairment of N-Methyl-D-Aspartate receptors is thought to contribute to negative symptoms and cognitive deficits. In vitro studies suggest that atypical antipsychotic drugs like clozapine may help to alleviate these deficits by enhancing glutamatergic function. The present study examined the in vivo interaction of clozapine with N-Methyl D-aspartate by training one group of C57BL/6 mice to discrimination 2.

Effects of sibutramine and rimonabant in rats trained to discriminate between 22- and 2-h food deprivation.

Objective: The objective of the study was to evaluate whether sibutramine and rimonabant, drugs that decrease food intake in human and non-human animals, affect the discriminative stimulus effects associated with acute food deprivation ("hunger").

Materials And Methods: Rats were trained to discriminate between 22- and 2-h food deprivation in a two-lever choice procedure. After rats acquired the discrimination, subjects were food-restricted for 22 h and administered with sibutramine (0.