Cannabis containing equivalent concentrations of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) induces less state anxiety than THC-dominant cannabis.

RATIONALE: Delta-9-tetrahydrocannabinol (THC), an active component of cannabis, can cause anxiety in some users during intoxication. Cannabidiol (CBD), another constituent of cannabis, has anxiolytic properties suggesting that cannabis products containing CBD in addition to THC may produce less anxiety than THC-only products. Findings to date around this issue have been inconclusive and could conceivably depend on moderating factors such as baseline anxiety levels in users. OBJECTIVE: The present study examined whether anxiety following single doses of vaporised THC, CBD and THC/CBD might be explained by state and trait anxiety levels at baseline. METHODS: A placebo-controlled, randomised, within-subjects study including 26 healthy recreational cannabis users tested the effects of vaporised THC-dominant cannabis (13.75 mg THC), CBD-dominant cannabis (13.75 mg CBD), THC/CBD-equivalent cannabis (13.75 mg THC/13.75 mg CBD) and placebo cannabis on anxiety. Self-rated trait anxiety was assessed with the State-Trait Anxiety Inventory (STAI). State levels of anxiety were objectively assessed with a computer-based emotional Stroop task (EST) and subjectively rated with the STAI-state questionnaire and a visual analogue scale. RESULTS: Both THC and THC/CBD significantly increased self-rated state anxiety compared to placebo. State anxiety after THC/CBD was significantly lower than after THC alone. THC-induced anxiety was independent of anxiety at baseline. When baseline anxiety was low, CBD completely counteracted THC-induced anxiety; however, when baseline anxiety was high, CBD did not counteract THC-induced anxiety. There were no effects of any treatment condition on the EST. CONCLUSION: Overall, the study demonstrated that the THC/CBD-equivalent cannabis induces less state anxiety than THC-dominant cannabis.

Oral THC:CBD cannabis extract for refractory chemotherapy-induced nausea and vomiting: a randomised, placebo-controlled, phase II crossover trial.

BACKGROUND: This multicentre, randomised, double-blinded, placebo-controlled, phase II/III trial aimed to evaluate an oral THC:CBD (tetrahydrocannabinol:cannabidiol) cannabis extract for prevention of refractory chemotherapy-induced nausea and vomiting (CINV). Here we report the phase II component results. PATIENTS AND METHODS: Eligible patients experienced CINV during moderate-to-high emetogenic intravenous chemotherapy despite guideline-consistent antiemetic prophylaxis. Study treatment consisted of one cycle of 1-4 self-titrated capsules of oral THC 2.5 mg/CBD 2.5 mg (TN-TC11M) three times daily, from days -1 to 5, and 1 cycle of matching placebo in a crossover design, then blinded patient preference for a third cycle. The primary end point was the proportion of participants with complete response during 0-120 h from chemotherapy. A total of 80 participants provided 80% power to detect a 20% absolute improvement with a two-sided P value of 0.1. RESULTS: A total of 81 participants were randomised; 72 completing two cycles were included in the efficacy analyses and 78 not withdrawing consent were included in safety analyses. Median age was 55 years (range 29-80 years); 78% were female. Complete response was improved with THC:CBD from 14% to 25% (relative risk 1.77, 90% confidence interval 1.12-2.79, P = 0.041), with similar effects on absence of emesis, use of rescue medications, absence of significant nausea, and summary scores for the Functional Living Index-Emesis (FLIE). Thirty-one percent experienced moderate or severe cannabinoid-related adverse events such as sedation, dizziness, or disorientation, but 83% of participants preferred cannabis to placebo. No serious adverse events were attributed to THC:CBD. CONCLUSION: The addition of oral THC:CBD to standard antiemetics was associated with less nausea and vomiting but additional side-effects. Most participants preferred THC:CBD to placebo. Based on these promising results, we plan to recruit an additional 170 participants to complete accrual for the definitive, phase III, parallel group analysis. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry ACTRN12616001036404; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=370473&isReview=true.

Effects of zinc source and dietary concentration on serum zinc concentrations, growth performance, wool and reproductive characteristics in developing rams.

Dietary Zn has significant impacts on the growth and development of breeding rams. The objectives of this study were to evaluate the effects of dietary Zn source and concentration on serum Zn concentration, growth performance, wool traits and reproductive performance in rams. Forty-four Targhee rams (14 months; 68 ± 18 kg BW) were used in an 84-day completely randomized design and were fed one of three pelleted dietary treatments: (1) a control without fortified Zn (CON; n = 15; ~1 × NRC); (2) a diet fortified with a Zn amino acid complex (ZnAA; n = 14; ~2 × NRC) and (3) a diet fortified with ZnSO4 (ZnSO4; n = 15; ~2 × NRC). Growth and wool characteristics measured throughout the course of the study were BW, average daily gain (ADG), dry matter intake (DMI), feed efficiency (G : F), longissimus dorsi muscle depth (LMD), back fat (BF), wool staple length (SL) and average fibre diameter (AFD). Blood was collected from each ram at four time periods to quantify serum Zn and testosterone concentrations. Semen was collected 1 to 2 days after the trial was completed. There were no differences in BW (P = 0.45), DMI (P = 0.18), LMD (P = 0.48), BF (P = 0.47) and AFD (P = 0.9) among treatment groups. ZnSO4 had greater (P ≤ 0.03) serum Zn concentrations compared with ZnAA and CON treatments. Rams consuming ZnAA had greater (P ≤ 0.03) ADG than ZnSO4 and CON. There tended to be differences among groups for G : F (P = 0.06), with ZnAA being numerically greater than ZnSO4 and CON. Wool staple length regrowth was greater (P < 0.001) in ZnSO4 and tended to be longer (P = 0.06) in ZnAA treatment group compared with CON. No differences were observed among treatments in scrotal circumference, testosterone, spermatozoa concentration within ram semen, % motility, % live sperm and % sperm abnormalities (P ≥ 0.23). Results indicated beneficial effects of feeding increased Zn concentrations to developing Targhee rams, although Zn source elicited differential responses in performance characteristics measured.

Author Correction: Composition and Use of Cannabis Extracts for Childhood Epilepsy in the Australian Community.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Composition and Use of Cannabis Extracts for Childhood Epilepsy in the Australian Community.

Recent surveys suggest that many parents are using illicit cannabis extracts in the hope of managing seizures in their children with epilepsy. In the current Australian study we conducted semi-structured interviews with families of children with diverse forms of epilepsy to explore their attitudes towards and experiences with using cannabis extracts. This included current or previous users of cannabis extracts to treat their child's seizures (n = 41 families), and families who had never used (n = 24 families). For those using cannabis, extracts were analysed for cannabinoid content, with specific comparison of samples rated by families as "effective" versus those rated "ineffective". Results showed that children given cannabis extracts tended to have more severe epilepsy historically and had trialled more anticonvulsants than those who had never received cannabis extracts. There was high variability in the cannabinoid content and profile of cannabis extracts rated as "effective", with no clear differences between extracts perceived as "effective" and "ineffective". Contrary to family's expectations, most samples contained low concentrations of cannabidiol, while Δ9-tetrahydrocannabinol was present in nearly every sample. These findings highlight profound variation in the illicit cannabis extracts being currently used in Australia and warrant further investigations into the therapeutic value of cannabinoids in epilepsy.

Cognitive, physical, and mental health outcomes between long-term cannabis and tobacco users.

INTRODUCTION: Cannabis intoxication adversely affects health, yet persistent effects following short-term abstinence in long-term cannabis users are unclear. This matched-subjects, cross-sectional study compared health outcomes of long-term cannabis and long-term tobacco-only users, relative to population norms. METHODS: Nineteen long-term (mean 32.3years of use, mean age 55.7years), abstinent (mean 15h) cannabis users and 16 long-term tobacco users (mean 37.1years of use, mean age 52.9years), matched for age, educational attainment, and lifetime tobacco consumption, were compared on measures of learning and memory, response inhibition, information-processing, sustained attention, executive control, and mental and physical health. RESULTS: Cannabis users exhibited poorer overall learning and delayed recall and greater interference and forgetting than tobacco users, and exhibited poorer recall than norms. Inhibition and executive control were similar between groups, but cannabis users had slower reaction times during information processing and sustained attention tasks. Cannabis users had superior health satisfaction and psychological, somatic, and general health than tobacco users and had similar mental and physical health to norms whilst tobacco users had greater stress, role limitations from emotional problems, and poorer health satisfaction. CONCLUSIONS: Long-term cannabis users may exhibit deficits in some cognitive domains despite short-term abstinence and may therefore benefit from interventions to improve cognitive performance. Tobacco alone may contribute to adverse mental and physical health outcomes, which requires appropriate control in future studies.

The direct actions of cannabidiol and 2-arachidonoyl glycerol at GABAA receptors.

Cannabidiol (CBD) is a major non-intoxicating component of cannabis and possesses anti-epileptic, anxiolytic and anti-hyperalgesic properties. The mechanism of action of CBD in producing such effects remains unclear. Despite evidence that some endogenous and synthetic cannabinoids interact with GABAA receptors, no-one has yet investigated the effects of CBD. Here we used two-electrode voltage clamp electrophysiology to compare the actions of CBD with those of the major central endocannabinoid, 2-arachidonoyl glycerol (2-AG) on human recombinant GABAA receptors (synaptic α1-6ßγ2 and extrasynaptic α4ß2δ) expressed on Xenopus oocytes. CBD and 2-AG were positive allosteric modulators at α1-6ßγ2 receptors, with low micromolar potencies. The maximal level of enhancement seen with either CBD or 2-AG were on α2-containing GABAA receptor subtypes, with approximately a 4-fold enhancement of the GABA EC5 evoked current, more than twice the potentiation seen with other α-subunit receptor combinations. Further we observed ß-subunit selectivity, whereby modulatory activity was higher at ß2/ß3 over ß1 subunits. The ß1-subunit homologous mutant ß2(V436T) substantially diminished the efficacy of both drugs to a third of that obtained with wild-type ß2 subunit combinations, but without changing potency. The potency of CBD increased and efficacy preserved in binary α1/α2ß2 receptors indicating that their effects do not involve the classic benzodiazepine site. Exploration of extrasynaptic α4ß2δ receptors revealed that both compounds enhanced GABA EC5 evoked currents at concentrations ranging from 0.01-1µM. Taken together these results reveal a mode of action of CBD on specifically configured GABAA receptors that may be relevant to the anticonvulsant and anxiolytic effects of the compound.

Clinical trials of medicinal cannabis for appetite-related symptoms from advanced cancer: a survey of preferences, attitudes and beliefs among patients willing to consider participation.

BACKGROUND: Australian clinical trials are planned to evaluate medicinal cannabis in a range of clinical contexts. AIMS: To explore the preferences, attitudes and beliefs of patients eligible and willing to consider participation in a clinical trial of medicinal cannabis for poor appetite and appetite-related symptoms from advanced cancer. METHODS: A cross-sectional anonymous survey was administered from July to December 2015 online and in eight adult outpatient palliative care and/or cancer services. Respondents were eligible if they were ≥18 years, had advanced cancer and poor appetite/taste problems/weight loss and might consider participating in a medicinal cannabis trial. Survey items focused on medicinal rather than recreational cannabis use and did not specify botanical or pharmaceutical products. Items asked about previous medicinal cannabis use and preferences for delivery route and invited comments and concerns. RESULTS: There were 204 survey respondents, of whom 26 (13%) reported prior medicinal cannabis use. Tablets/capsules were the preferred delivery mode (n = 144, 71%), followed by mouth spray (n = 84, 42%) and vaporiser (n = 83, 41%). Explanations for preferences (n = 134) most commonly cited convenience (n = 66; 49%). A total of 82% (n = 168) of respondents indicated that they had no trial-related concerns, but a small number volunteered concerns about adverse effects (n = 14) or wanted more information/advice (n = 8). Six respondents volunteered a belief that cannabis might cure cancer, while two wanted assurance of efficacy before participating in a trial. CONCLUSION: Justification of modes other than tablets/capsules and variable understanding about cannabis and trials will need addressing in trial-related information to optimise recruitment and ensure that consent is properly informed.

Chronic Methamphetamine Self-Administration Dysregulates Oxytocin Plasma Levels and Oxytocin Receptor Fibre Density in the Nucleus Accumbens Core and Subthalamic Nucleus of the Rat.

The neuropeptide oxytocin attenuates reward and abuse for the psychostimulant methamphetamine (METH). Recent findings have implicated the nucleus accumbens (NAc) core and subthalamic nucleus (STh) in oxytocin modulation of acute METH reward and relapse to METH-seeking behaviour. Surprisingly, the oxytocin receptor (OTR) is only modestly involved in both regions in oxytocin attenuation of METH-primed reinstatement. Coupled with the limited investigation of the role of the OTR in psychostimulant-induced behaviours, we primarily investigated whether there are cellular changes to the OTR in the NAc core and STh, as well as changes to oxytocin plasma levels, after chronic METH i.v. self-administration (IVSA) and after extinction of drug-taking. An additional aim was to examine whether changes to central corticotrophin-releasing factor (CRF) and plasma corticosterone levels were also apparent because of the interaction of oxytocin with stress-regulatory mechanisms. Male Sprague-Dawley rats were trained to lever press for i.v. METH (0.1 mg/kg/infusion) under a fixed-ratio 1 schedule or received yoked saline infusions during 2-h sessions for 20 days. An additional cohort of rats underwent behavioural extinction for 15 days after METH IVSA. Subsequent to the last day of IVSA or extinction, blood plasma was collected for enzyme immunoassay, and immunofluorescence was conducted on NAc core and STh coronal sections. Rats that self-administered METH had higher oxytocin plasma levels, and decreased OTR-immunoreactive (-IR) fibres in the NAc core than yoked controls. In animals that self-administered METH and underwent extinction, oxytocin plasma levels remained elevated, OTR-IR fibre density increased in the STh, and a trend towards normalisation of OTR-IR fibre density was evident in the NAc core. CRF-IR fibre density in both brain regions and corticosterone plasma levels did not change across treatment groups. These findings demonstrate that oxytocin systems, both centrally within the NAc core and STh, as well as peripherally through plasma measures, are dysregulated after METH abuse.

Cannabinoid replacement therapy (CRT): Nabiximols (Sativex) as a novel treatment for cannabis withdrawal.

Cannabis is a common recreational drug that is generally considered to have low addictive potential. However, an increasing number of cannabis users are seeking treatment for dependence on the drug. There is interest in using agonist (substitution) pharmacotherapies to treat cannabis dependence and here we outline a novel approach involving a buccal spray (nabiximols) that contains tetrahydrocannabinol (THC) and cannabidiol (CBD). We review recent research with nabiximols and highlight findings relevant to clinical practice.

Regional Fos-expression induced by γ-hydroxybutyrate (GHB): comparison with γ-butyrolactone (GBL) and effects of co-administration of the GABAB antagonist SCH 50911 and putative GHB antagonist NCS-382.

γ-Hydroxybutyrate (GHB) has a complex array of neural actions that include effects on its own high-affinity GHB receptor, the release of neuroactive steroids, and agonist actions at GABAA and GABAB receptors. We previously reported partial overlap in the c-Fos expression patterns produced by GHB and the GABAB agonist, baclofen in rats. The present study extends these earlier findings by examining the extent to which GHB Fos expression and behavioral sedation are prevented by (2S)-(+)-5,5-dimethyl-2-morpholineacetic acid (SCH 50911), a GABAB antagonist, and NCS-382, a putative antagonist at the high-affinity GHB receptor. We also compare Fos expression caused by GHB and its precursor γ-butyrolactone (GBL), which is a pro-drug for GHB but lacks the high sodium content of the parent GHB molecule. Both GHB (1,000 mg/kg) and GBL (600 mg/kg) induced rapid sedation in rats that lasted over 90 min and caused similar Fos expression patterns, albeit with GBL causing greater activation of the nucleus accumbens (core and shell) and dentate gyrus (granular layer). Pretreatment with SCH 50911 (100mg/kg) partly reversed the sedative effects of GHB and significantly reduced GHB-induced Fos expression in only four regions: the tenia tecta, lateral habenula, dorsal raphe and laterodorsal tegmental nucleus. NCS-382 (50mg/kg) had no effect on GHB-induced sedation or Fos expression. When given alone, both NCS-382 and SCH 50911 increased Fos expression in the bed nucleus of the stria terminalis, central amygdala, parasubthalamic nucleus and nucleus of the solitary tract. SCH 50911 alone affected the Islands of Calleja and the medial, central and paraventricular thalamic nuclei. Overall, this study shows a surprising lack of reversal of GHB-induced Fos expression by two relevant antagonists, both of which have marked intrinsic actions. This may reflect the limited doses tested but also suggests that GHB Fos expression reflects mechanisms independent of GHB and GABAB receptors.

Body temperature and cardiac changes induced by peripherally administered oxytocin, vasopressin and the non-peptide oxytocin receptor agonist WAY 267,464: a biotelemetry study in rats.

BACKGROUND AND PURPOSE: There is current interest in oxytocin (OT) as a possible therapeutic in psychiatric disorders. However, the usefulness of OT may be constrained by peripheral autonomic effects, which may involve an action at both OT and vasopressin V1A receptors. Here, we characterized the cardiovascular and thermoregulatory effects of OT, vasopressin (AVP) and the non-peptide OT receptor agonist WAY 267,464 in rats, and assessed the relative involvement of the OT and V1A receptors in these effects. EXPERIMENTAL APPROACH: Biotelemetry in freely moving male Wistar rats was used to examine body temperature and heart rate after OT (0.01 - 1 mg kg(-1); i.p.), AVP (0.001 - 0.1 mg kg(-1); i.p.) or WAY 267,464 (10 and 100 mg kg(-1); i.p.). The actions of the OT receptor antagonist Compound 25 (C25, 5 and 10 mg kg(-1)) and V1A receptor antagonist SR49059 (1 and 10 mg kg(-1)) were studied, as well as possible V1A receptor antagonist effects of WAY 267,464. KEY RESULTS: OT and AVP dose-dependently reduced body temperature and heart rate. WAY 267,464 had similar, but more modest, effects. SR49059, but not C25, prevented the hypothermia and bradycardia induced by OT and AVP. WAY 267,464 (100 mg·kg(-1)) prevented the effects of OT, and to some extent AVP. CONCLUSIONS AND IMPLICATIONS: Peripherally administered OT and AVP have profound cardiovascular and thermoregulatory effects that appear to principally involve the V1A receptor rather than the OT receptor. Additionally, WAY 267,464 is not a simple OT receptor agonist, as it has functionally relevant V1A antagonist actions.

Interleukin-18 deficiency and its long-term behavioural and cognitive impacts in a murine model of pneumococcal meningitis.

Pneumococcal meningitis often results in death or neurological sequelae, but the underlying pathogenetic mechanisms remain poorly understood. In C57BL/6J mice subjected to intracerebroventricular (icv) challenge with Streptococcus pneumoniae, the chemokine CCL2 and cytokines interferon-γ, interleukin (IL)-1ß, IL-6 and tumour necrosis factor were prominently expressed in the brain during the acute phase of the disease. The upregulation of these immune mediators was markedly diminished in IL-18-deficient mice. Uninfected IL-18(-/-) mice exhibited decreases in anxiety phenotype and licking behaviour, and an increase in behavioural habituation, in an automated monitoring system (the IntelliCage). Without antibiotic intervention, a majority of IL-18(+/+) mice developed irreversible disease after icv S. pneumoniae but this was significantly improved by deleting IL-18 gene function. IL-18(+/+) mice cured of pneumococcal meningitis with four doses of ceftriaxone, initiated at 20 h post-inoculation, showed enduring sequelae. These included abnormal behavioural phenotypes featuring diurnal hypoactivity and nocturnal hyperactivity, light phobia and disrupted cognitive function. While the hyperactive phenotype was absent in the corresponding IL-18(-/-) survivors, cognitive impairments and behavioural deficits were still present. Overall, the results suggest that the high levels of cytokines and/or chemokines released after pneumococcal challenge provoked a series of pathological events, ultimately causing acute death. Furthermore, since only a subset of behavioural phenotypes were ameliorated in the pneumococcus-infected IL-18(-/-) mice, the pathological pathways causing mortality may be, at least in part, distinct from those leading to long-term neurological sequelae.

A novel automated test battery reveals enduring behavioural alterations and cognitive impairments in survivors of murine pneumococcal meningitis.

Pneumococcal meningitis, caused by Streptococcus pneumoniae infection, is a major form of lethal bacterial meningitis. Survivors are predisposed to developing lifelong disabling sequelae, including cognitive impairment, psychological problems and motor deficits. In our experimental model, ventricular inoculation of 10(5) colony-forming units of S. pneumoniae type 3 caused 90% of mice to develop life-threatening meningitis within 48 h. Antibiotic treatment with ceftriaxone 20 h post infection reduced the incidence of severe meningitis to <10%. At the time of treatment, upregulation of pro-inflammatory cytokines was detected, including interleukin-1ß, interleukin-6 and tumour necrosis factor. We evaluated the long-term behavioural and cognitive sequelae in control mice and those surviving meningitis using an automated system (the IntelliCage) in which mice perform a range of behavioural and spatial tasks to obtain water rewards from conditioning units in their home cage. Surviving mice showed a number of altered behaviours relative to controls, including (i) hypoexploration when first exposed to the IntelliCage, (ii) altered activity patterns (fewer visits to conditioning stations during the light phase and more in the dark phase), (iii) avoidance of light (a constant or flashing LED stimulus), (iv) impaired spatial learning (a complex patrolling task), and (v) impaired discrimination reversal learning. Overall these results suggest photophobia and weakened learning ability in post-meningitic mice, particularly on tasks engaging hippocampal and prefrontal neural substrates. This study also demonstrates a standardised and comprehensive battery of tests that can be readily used to investigate neurological sequelae in undisturbed mice residing in a complex home cage environment.

The nonpeptide oxytocin receptor agonist WAY 267,464: receptor-binding profile, prosocial effects and distribution of c-Fos expression in adolescent rats.

Previous research suggests that the nonpeptide oxytocin receptor (OTR) agonist WAY 267,464 may only partly mimic the effects of oxytocin in rodents. The present study further explored these differences and related them to OTR and vasopressin 1a receptor (V(1a) R) pharmacology and regional patterns of c-Fos expression. Binding data for WAY 267,464 and oxytocin were obtained by displacement binding assays on cellular membranes, while functional receptor data were generated by luciferase reporter assays. For behavioural testing, adolescent rats were tested in a social preference paradigm, the elevated plus-maze (EPM) and for locomotor activity changes following WAY 267,464 (10 and 100 mg/kg, i.p.) or oxytocin (0.1 and 1 mg/kg, i.p.). The higher doses were also examined for their effects on regional c-Fos expression. Results showed that WAY 267,464 had higher affinity (K(i) ) at the V(1a) R than the OTR (113 versus 978 nm). However, it had no functional response at the V(1a) R and only a weak functional effect (EC(50) ) at the OTR (881 nm). This suggests WAY 267,464 is an OTR agonist with weak affinity and a possible V(1a) R antagonist. Oxytocin showed high binding at the OTR (1.0 nm) and V(1a) R (503 nm), with a functional EC(50) of 9.0 and 59.7 nm, respectively, indicating it is a potent OTR agonist and full V(1a) R agonist. WAY 267,464 (100 mg/kg), but not oxytocin, significantly increased the proportion of time spent with a live rat, over a dummy rat, in the social preference test. Neither compound affected EPM behaviour, whereas the higher doses of WAY 267,464 and oxytocin suppressed locomotor activity. WAY 267,464 and oxytocin produced similar c-Fos expression in the paraventricular hypothalamic nucleus, central amygdala, lateral parabrachial nucleus and nucleus of the solitary tract, suggesting a commonality of action at the OTR with the differential doses employed. However, WAY 267,464 caused greater c-Fos expression in the medial amygdala and the supraoptic nucleus than oxytocin, and lesser effects in the locus coeruleus. Overall, our results confirm the differential effects of WAY 267,464 and oxytocin and suggest that this may reflect contrasting actions of WAY 267,464 and oxytocin at the V(1a) R. Antagonism of the V(1a) R by WAY 267,464 could underlie some of the prosocial effects of this drug either through a direct action or through disinhibition of oxytocin circuitry that is subject to vasopressin inhibitory influences.

Regional c-Fos and FosB/ΔFosB expression associated with chronic methamphetamine self-administration and methamphetamine-seeking behavior in rats.

The regional expression of the transcription factors c-Fos and FosB/ΔFosB was examined in rats given acute exposure to intravenous methamphetamine (METH) or repeated intravenous METH self-administration. One group of rats self-administered METH via lever pressing in 2 h sessions every day for 3 weeks and on a final test day received self-administered METH as usual. A second group with the same METH self-administration history received saline infusions on the test day, to induce drug-seeking behavior. Other rats were trained with infusions of intravenous saline that were yoked to the passive delivery of METH in the other two groups. On test day, half of these yoked rats received passive METH infusions for the first time, whereas the others received saline as usual. The results showed that acute METH produced a characteristic signature of Fos expression with elevations in striatal, cortical, and extended amygdala regions. Importantly, rats with a 3-week history of METH self-administration displayed similar regional Fos expression to rats receiving METH for the first time. Rats seeking, but not receiving, METH on the test day had augmented Fos in the lateral hypothalamus, septum, and vertical limb of the diagonal band of Broca, suggesting a primary role for these regions in METH-seeking behavior. Both acute and chronic METH activated orexin-positive cells in the perifornical area of the hypothalamus. FosB/ΔFosB was elevated in the lateral hypothalamus, posterior ventral tegmental area, central amygdala, and dorsal raphe of all the rats with a history of METH self-administration. This occurred regardless of whether they received METH on test day, suggesting presence of the long-lived FosB isoform, ΔFosB. Overall, these results show persistent upregulated regional brain Fos and FosB/ΔFosB expression with chronic METH self-administration and indicate a role for the lateral hypothalamus and lateral septum in METH-seeking behavior.

The major plant-derived cannabinoid Δ(9)-tetrahydrocannabinol promotes hypertrophy and macrophage infiltration in adipose tissue.

Synthetic cannabinoid receptor agonists activate lipoprotein lipase and the formation of lipid droplets in cultured adipocytes. Here we extend this work by examining whether Δ(9)-tetrahydrocannabinol (THC), a major plant-derived cannabinoid, increases adipocyte size in vivo. Further, possibly as a consequence of hypertrophy, we hypothesize that THC exposure promotes macrophage infiltration into adipose tissue, an inflammatory state observed in obese individuals. Rats repeatedly exposed to THC in vivo had reduced body weight, fat pad weight, and ingested less food over the drug injection period. However, THC promoted adipocyte hypertrophy that was accompanied by a significant increase in cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C) expression, an enzyme important in packaging triglycerides. We also showed that THC induced macrophage infiltration and increased expression of the inflammatory cytokine tumor necrosis factor alpha (TNF-α) in adipose tissue but did not induce apoptosis as measured by TUNEL staining. That THC increased adipocyte cell size in the absence of greater food intake, body weight and fat provides a unique model to explore mechanisms underlying changes in adipocyte size associated with a mild inflammatory state in fat tissue.

Resilience and reduced c-Fos expression in P2X7 receptor knockout mice exposed to repeated forced swim test.

There is considerable evidence suggesting genetic factors play an important role in the pathophysiology of depression, possibly by increasing susceptibility to repeated environmental stressors. Recent linkage studies have associated a polymorphism of the gene coding for the P2X7 receptor (P2X7R) with both major depressive disorder and bipolar disorder. Here we assessed whether P2X7 deletion affected the behavioural and neural response to repeated stress. P2X7R knockout (P2X7-/-) mice were subjected to the forced swim test for three consecutive days and neuronal activation in response to the third exposure was assessed using c-Fos immunohistochemistry. In addition, anxiety was evaluated in another group of P2X7-/- mice using the elevated plus maze (EPM) and light dark emergence (LDE) tests. Equivalent levels of immobility were observed in P2X7-/- mice and wild-type (WT) mice on the first exposure to forced swim, but much greater immobility was seen in WT mice on second and third exposures. This suggests that P2X7-/- mice exhibit an impaired adaptive coping response to repeated stress. Reinforcing this view, c-Fos expression in the dentate gyrus of the hippocampus and in the basolateral amygdala was seen in WT mice but not P2X7-/- mice following repeated forced swim. In addition, decreased locomotor activity was detected in P2X7-/- mice without any specific effects on anxiety in the LDE test. However, P2X7-/- mice showed greater anxiety-like behaviour in the EPM. These data suggest that the P2X7R may be involved in the adaptive mechanisms elicited by exposure to repeated environmental stressors that leads to the development of depression-like behaviours. This suggests that P2X7R antagonists may be useful therapeutics for the treatment of major depression, possibly by increasing resilience in the face of repeated stress.

Weekly gamma-hydroxybutyrate exposure sensitizes locomotor hyperactivity to low-dose 3,4-methylenedioxymethamphetamine in rats.

Users of the popular party drug 3,4-methylenedioxymethamphetamine (MDMA) sometimes report combining MDMA with gamma-hydroxybutyrate (GHB) to enhance the pleasurable effects of both drugs. However, very few studies have examined the influences of this drug combination. The present study investigated the development of locomotor sensitization in laboratory rats given 7 once-weekly exposures to either MDMA, GHB or their combination (MDMA/GHB). The drugs were administered at a high ambient temperature (28 degrees C) to mimic nightclub conditions. MDMA (5 mg/kg), given once weekly, produced a progressively greater locomotor and hyperthermic response over time. In contrast, GHB (500 mg/kg) administered weekly produced consistent low levels of locomotor activity and few changes in body temperature. Rats receiving the mixture of MDMA (5 mg/kg) and GHB (500 mg/kg) showed asymptotic levels of sensitized locomotor activity similar to those seen in rats given MDMA alone, but the development of locomotor sensitization was delayed by coadministered GHB. GHB also delayed the development of MDMA-induced hyperthermia. After a washout period of 5 weeks, rats pre-exposed to MDMA, GHB and MDMA/GHB showed no hyperactivity when tested drug-free in the context in which they had previously received drugs, but displayed a sensitized locomotor response to a low challenge dose of MDMA (2.5 mg/kg). The response to a low dose of methamphetamine (0.5 mg/kg) did not differ among groups. Neurochemical analysis using high-performance liquid chromatography revealed few lasting changes in serotonin, dopamine or their metabolites in the striatum or prefrontal cortex of MDMA- or GHB-pre-exposed rats. These results indicate that GHB modulates the locomotor and hyperthermic response to acute MDMA and that pre-exposure to GHB can sensitize the locomotor response to low doses of MDMA.

Reintoxication: the release of fat-stored delta(9)-tetrahydrocannabinol (THC) into blood is enhanced by food deprivation or ACTH exposure.

BACKGROUND AND PURPOSE: Delta(9)-tetrahydrocannabinol (THC), the main psychoactive constituent of cannabis, accumulates in adipose tissue where it is stored for long periods of time. Here we investigated whether conditions that promote lipolysis can liberate THC from adipocytes to yield increased blood levels of THC. EXPERIMENTAL APPROACH: In vitro studies involved freshly isolated rat adipocytes that were incubated with THC before exposure to the lipolytic agent adrenocorticotrophic hormone (ACTH). A complementary in vivo approach examined the effects of both food deprivation and ACTH on blood levels of THC in rats that had been repeatedly injected with THC (10 mg.kg(-1)) for 10 consecutive days. Lipolysis promoted by ACTH or food deprivation was indexed by measurement of glycerol levels. KEY RESULTS: ACTH increased THC levels in the medium of THC-pretreated adipocytes in vitro. ACTH also enhanced THC release from adipocytes in vitro when taken from rats repeatedly pretreated with THC in vivo. Finally, in vivo ACTH exposure and 24 h food deprivation both enhanced the levels of THC and its metabolite, (-)-11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (THC-COOH) in the blood of rats that had been pre-exposed to repeated THC injections. CONCLUSIONS AND IMPLICATIONS: The present study shows that lipolysis enhances the release of THC from fat stores back into blood. This suggests the likelihood of 'reintoxication' whereby food deprivation or stress may raise blood THC levels in animals chronically exposed to the drug. Further research will need to confirm whether this can lead to functional effects, such as impaired cognitive function or 'flashbacks'.