Dual fatty acid amide hydrolase and monoacylglycerol lipase blockade produces THC-like Morris water maze deficits in mice.

Acute administration of Δ(9)-tetrahydrocannabinol (THC) or exposure to marijuana smoke impairs short-term spatial memory in water maze tasks through a CB(1) receptor mechanism of action. N-Arachidonoylethanolamine (anandamide; AEA) and 2-arachidonoylglycerol (2-AG) are endogenous cannabinoids that are predominantly metabolized by the respective enzymes fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL). Although the MAGL inhibitor JZL184 enhances short-term synaptic plasticity, it has yet to be evaluated in the Morris water maze. Previous research demonstrated that simultaneous, complete blockade of FAAH and MAGL produces full blown THC-like effects. Thus, in the following studies we tested whether dual blockade of FAAH and MAGL would impair learning in a repeated acquisition Morris water maze task. Mice treated with the dual FAAH/MAGL inhibitor JZL195 (20 mg/kg) as well as JZL184-treated FAAH -/- mice displayed robust deficits in Morris water maze performance that were similar in magnitude to THC-treated mice. While 20 or 40 mg/kg impaired water maze performance in FAAH -/- mice, only the high dose of JZL184 disrupted performance in FAAH +/+ mice. The memory impairing effects of JZL184 were blocked by the CB(1) receptor antagonist rimonabant. Neither JZL184 nor JZL195 impaired performance in a cued version of the water maze task, arguing against the notion that sensorimotor or motivational deficits accounted for the impaired acquisition performance. JZL184 increased 2-AG levels in the hippocampus, prefrontal cortex, and cerebellum to a similar degree in FAAH -/- and +/+ mice. FAAH -/- mice, regardless of drug treatment, possessed elevated AEA levels in each brain region assessed. The results of this study reveal that concomitant increases in AEA and 2-AG disrupt short-term spatial memory performance in a manner similar to that of THC.

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. We also evaluated whether rimonabant would precipitate adenylyl cyclase superactivation in hippocampal and cerebellar tissue from THC-dependent mice. RESULTS: Rimonabant significantly impaired spatial memory of THC-dependent mice at lower doses than those necessary to precipitate somatic withdrawal behavior. In contrast, maze performance was near perfect in the cued task, suggesting sensorimotor function and motivational factors were unperturbed by the withdrawal state. Finally, rimonabant increased adenylyl cyclase activity in cerebellar, but not in hippocampal, membranes. CONCLUSIONS: The memory disruptive effects of THC undergo tolerance following repeated dosing, while the withdrawal state leads to a rebound deficit in memory. These results establish spatial memory impairment as a particularly sensitive component of cannabinoid withdrawal, an effect that may be mediated through compensatory changes in the cerebellum.

Disposition of cannabichromene, cannabidiol, and Δ9-tetrahydrocannabinol and its metabolites in mouse brain following marijuana inhalation determined by high-performance liquid chromatography-tandem mass spectrometry.

A liquid chromatography-tandem mass spectrometry (LC-MS-MS)method was developed for the analysis of marijuana cannabinoids in mouse brain tissue using an Applied Biosystems 3200 Q trap with a turbo V source for TurbolonSpray attached to a Shimadzu SCL HPLC system. The method included cannabichromene (CBC),cannabidiol (CBD), Δ9-tetrahydrocannabinol (THC), 11-hydroxytetrahydrocannabinol (11-OH-THC), and 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH). These compounds were isolated by liquid-liquid extraction using cold acetonitrile. The following transition ions were monitored by multiple reaction monitoring (MRM): m/z 315>193, 315>259 for THC/CBD/CBC; m/z 331>193, 331>105 for 11-OH-THC; m/z 345>299, 345>193 for THC-COOH; m/z 318>196 for THC-d3; m/z 334>196 for 11-OH-THC-d3, and m/z 348>302 for THC-COOH-d3. Linearity for THC, 1-OH-THC, and THC-COOH was 1-200 ng/g; for CBC and CBD, it was 0.5-20 ng/g. Within-run and between-run precisions for all the analytes yielded coefficients of variation of < 20%. Four C57BL6 mice were sacrificed 20 min after nose-only exposure to the smoke of 200 mg of marijuana containing 0.44 mg CBC, 0.93 mg CBD, and 8.81 mg THC. The mean brain concentrations were 3.9 ± 1.5 ng/g CBC, 21 ± 3.9 ng/g CBD, 364 ± 74 ng/g THC, and 28 ± 5.9 ng/g 11-OH-THC. THC-COOH was not detected. The relative mean brain cannabinoid concentrations correlated to the amounts of the cannabinoids in the inhaled marijuana.