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Systemic or intrahippocampal cannabinoid administration impairs spatial memory in rats.

The purpose of the present study was to investigate the disruptive effects of cannabinoids on working memory as assessed in the eight-arm radial-maze. Systemic administration of delta 9-THC, WIN-55,212-2, and CP-55,940 increased the number of errors committed in the radial-maze. CP-55,940 was the most potent cannabinoid in impairing memory (ED50 = 0.13 mg/kg). delta 9-THC and WIN-55,212-2 disrupted maze-choice accuracy at equipotent doses (ED50 values = 2.1 and 2.2 mg/kg, respectively). In addition, systemic administration of each of these agents retarded completion time. Whereas the doses of delta 9-THC and CP-55,940 required to retard maze performance were higher than those needed to increase error numbers, WIN-55,212-2 was equipotent in both of these measures. On the other hand, neither anandamide, the putative endogenous cannabinoid ligand, nor cannabidiol, an inactive naturally occurring cannabinoid, had any apparent effects on memory. A second aim of this study was to elucidate the neuroanatomical substrates mediating the disruptive effects of cannabinoids on memory. Intrahippocampal injections of CP-55,940 impaired maze performance in a dose-dependent manner (ED50 = 8 micrograms/rat), but did not retard the amount of time required to complete the maze. The effects of intrahippocampal CP-55,940 were apparently specific to cognition because no other cannabinoid pharmacological effects (e.g., antinociception, hypothermia, and catalepsy) were detected. This dissociation between choice accuracy in the radial-maze and other cannabinoid pharmacological effects suggests that the working memory deficits produced by cannabinoids may be mediated by cannabinoid receptors in the hippocampus.

Analgesics↗

Effects of the cannabinoid CB1 receptor antagonist SR141716A on the behavior of pigeons and rats.

SR141716A (Sanofi Recherche), a pyrazole derivative with high affinity for rat and human CB1 cannabinoid receptors, has recently been reported to reverse biochemical, physiological and behavioral effects induced by cannabinoid agonists. The present experiments characterized the activity of SR141716A (SR) in behavioral procedures designed to assess its antagonistic and intrinsic effects on unconditioned behavior and on complex learned behaviors. Six adult male pigeons were trained to discriminate injections of 0.56 mg/kg delta 9-tetrahydrocannabinol (delta 9-THC) from vehicle under a two-key, fixed-ratio schedule of food reinforcement. SR (IM) produced a nearly complete blockade of THC-appropriate responding occasioned by the training dose without inducing significant changes in session response rates, but also produced partial substitution for delta 9-THC when administered alone. In another group of pigeons trained under a multiple schedule of signaled and unsignaled fixed consecutive number (FCN) responding, SR had little effect on accuracy, but delta 9-THC produced dose-related decreases in accuracy under both schedule components. SR was also evaluated in acoustic startle procedures in rats. SR produced little effect either on startle amplitude or prepulse inhibition of acoustic startle. In contrast, the potent cannabinomimetic CP-55, 940 produced large decreases in startle responses elicited by 120 dB [A] broad-band noise. These decreases were completely reversed by SR (10 mg/kg, IP). In concurrent measures, SR blocked the hypothermic effect CP-55,940. These results suggest that SR is an effective antagonist of the psychoactive effects of cannabinoids.

Animals↗

Pretreatment with 1,8-cineole potentiates thioacetamide-induced hepatotoxicity and immunosuppression.

The effect of 1,8-cineole on cytochrome P450 (CYP) expression was investigated in male Sprague Dawley rats and female BALB/c mice. When rats were treated orally with 200, 400 and 800 mg/kg of 1,8-cineole for 3 consecutive days, the liver microsomal activities of benzyloxyresorufin- and pentoxyresorufin-omicron-dealkylases and erythromycin N-demethylase were dose-dependently induced. The Western immunoblotting analyses clearly indicated the induction of CYP 2B1/2 and CYP 3A1/2 proteins by 1,8-cineole. At the doses employed, 1,8-cineole did not cause toxicity, including hepatotoxicity. Subsequently, 1,8-cineole was applied to study the role of metabolic activation in thioacetamide-induced hepatotoxicity and/or immunotoxicity in animal models. To investigate a possible role of metabolic activation by CYP enzymes in thioacetamide-induced hepatotoxicity, rats were pre-treated with 800 mg/kg of 1 ,8-cineole for 3 days, followed by a single intraperitoneal treatment with 50 and 100 mg/kg of thioacetamide in saline. 24 h later, thioacetamide-induced hepatotoxicity was significantly potentiated by the pretreatment with 1,8-cineole. When female BALB/c mice were pretreated with 800 mg/kg of 1,8-cineole for 3 days, followed by a single intraperitoneal treatment with 100 mg/kg of thioacetamide, the antibody response to sheep red blood cells was significantly potentiated. In addition, the liver microsomal activities of CYP 2B enzymes were significantly induced by 1,8-cineole as in rats. Taken together, our results indicated that 1,8-cineole might be a useful CYP modulator in investigating the possible role of metabolic activation in chemical-induced hepatotoxicity and immunotoxicity.

Alanine Transaminase↗

Fentanyl-induced rigidity during emergence from general anesthesia potentiated by venlafexine.

PURPOSE: To present and discuss a case of opioid-induced rigidity with low-dose fentanyl during recovery from anesthesia. CLINICAL FEATURES: A 41-yr-old woman underwent laparotomy for total abdominal hysterectomy and bilateral salpingo- oophorectomy under general anesthesia. She received a total of 500 micro g of fentanyl by iv intermittent boluses during the three-hour anesthetic. During emergence from anesthesia, while intubated, the patient presented with rigidity. No changes in ventilatory parameters were measured during the episode. The only notable predisposing factor was treatment with venlafexine, an antidepressant that modifies serotonin and norepinephrine levels. She was successfully treated with iv naloxone 20 micro g. The rest of the postoperative period was uneventful. CONCLUSION: We observed an atypical case of opioid-induced rigidity in contrast to the classical syndrome, which presents at induction with high-dose opioids. This syndrome has many clinical presentations with neurologic and ventilatory signs of varying intensity. Early recognition of the syndrome and adequate treatment is crucial. If treated adequately, opioid-induced rigidity is self-limited with few complications.

Adult↗

Venlafaxine versus fluoxetine in the treatment of atypical anorectic outpatients: a preliminary study.

The efficacy of venlafaxine and fluoxetine in the treatment of atypical anorexia nervosa (AN) was compared in a controlled trial. A consecutive series of 24 atypical anorectic females was assigned to either venlafaxine (75 mg/day) or fluoxetine (40 mg/day) plus cognitive-behavioural therapy (CBT). Eating Disorder Examination (EDE12.0D), Beck Depression Inventory (BDI) and State and Trait Anxiety Inventory (STAI) scores were compared before and after 6 months of treatment. Venlafaxine and fluoxetine determined an increase of body mass index (BMI) and a significant reduction of EDE12.0D and BDI scores; venlafaxine alone reduced STAI scores. It would seem that venlafaxine is as effective as fluoxetine when combined with CBT in the treatment of atypical AN.

Adolescent↗

Cannabinoid CB1 receptor-mediated inhibition of NMDA- and kainate-stimulated noradrenaline and dopamine release in the brain.

Guinea-pig hippocampal slices preincubated with [3H]noradrenaline were superfused with medium containing desipramine and rauwolscine and rat striatal slices preincubated with [3H]dopamine were superfused with medium containing nomifensine; the effect of cannabinoid receptor ligands on tritium overflow stimulated by NMDA or kainate was examined. Furthermore, the affinity of the drugs for cannabinoid CB1 receptors was determined in rat brain cortex membranes using [3H]SR 141716. In guinea-pig hippocampal slices preincubated with [3H]noradrenaline, tritium overflow stimulated by NMDA 100 microM and 1000 microM and by kainate 1000 microM was inhibited by the cannabinoid receptor agonists CP-55,940 and/or WIN 55,212-2. The CB1 receptor antagonist SR 141716 increased the NMDA (1000 microM)-stimulated tritium overflow but did not affect tritium overflow stimulated by NMDA 100 microM or kainate 1000 microM. The inhibitory effect of WIN 55,212-2 on the NMDA (100 microM)- and kainate (1000 microM)-evoked tritium overflow was antagonized by SR 141716. In rat striatal slices preincubated with [3H]dopamine, WIN 55,212-2 inhibited the NMDA (1000 microM)-stimulated tritium overflow. SR 141716, which, by itself, did not affect tritium overflow, counteracted the inhibitory effect of WIN 55,212-2. [3H]SR 141716 binding to rat cortical membranes was inhibited by SR 141716, CP-55,940 and WIN 55,212-2 (pKi 8.53, 7.34 and 5.93, respectively) but not affected by desipramine, rauwolscine and nomifensine (pKi < 5). In conclusion, activation of CB1 receptors inhibits the NMDA- and kainate-stimulated noradrenaline release in guinea-pig hippocampus and the NMDA-stimulated dopamine release in rat striatum. The explanation for the facilitatory effect of SR 141716 might be that it acts as an inverse agonist at CB1 receptors or that these receptors are activated by endogenous cannabinoids.

Animals↗

Terpinen-4-ol, the main component of the essential oil of Melaleuca alternifolia (tea tree oil), suppresses inflammatory mediator production by activated human monocytes.

OBJECTIVE AND DESIGN: To evaluate potential antiinflammatory properties of tea tree oil, the essential oil steam distilled from the Australian native plant, Melaleuca alternifolia. MATERIAL AND METHODS: The ability of tea tree oil to reduce the production in vitro of tumour necrosis factor-alpha (TNFalpha), interleukin (IL)-1beta, IL-8, IL-10 and prostaglandin E2 (PGE2) by lipopolysaccharide (LPS)-activated human peripheral blood monocytes was examined. RESULTS: Tea tree oil emulsified by sonication in a glass tube into culture medium containing 10% fetal calf serum (FCS) was toxic for monocytes at a concentration of 0.016% v/v. However, the water soluble components of tea tree oil at concentrations equivalent to 0.125% significantly suppressed LPS-induced production of TNFalpha, IL-1beta and IL-10 (by approximately 50%) and PGE2 (by approximately 30%) after 40 h. Gas chromatography/mass spectrometry identified terpinen-4-ol (42 %), a-terpineol (3 %) and 1,8-cineole (2%, respectively, of tea tree oil) as the water soluble components of tea tree oil. When these components were examined individually, only terpinen-4-ol suppressed the production after 40 h of TNFalpha, IL-1beta, IL-8, IL-10 and PGE2 by LPS-activated monocytes. CONCLUSION: The water-soluble components of tea tree oil can suppress pro-inflammatory mediator production by activated human monocytes.

Anti-Inflammatory Agents, Non-Steroidal↗

The water-soluble components of the essential oil of Melaleuca alternifolia (tea tree oil) suppress the production of superoxide by human monocytes, but not neutrophils, activated in vitro.

OBJECTIVE: To evaluate the regulatory properties of the essential oil of Melaleuca alternifolia (tea tree oil) on the production of oxygen derived reactive species by human peripheral blood leukocytes activated in vitro. MATERIALS AND METHODS: The ability of tea tree oil to reduce superoxide production by neutrophils and monocytes stimulated with N-formyl-methionyl-leucyl-phenylalanine (fMLP), lipopolysaccharide (LPS) or phorbol 12-myristate 13-acetate (PMA) was examined. RESULTS: The water-soluble fraction of tea tree oil had no significant effect on agonist-stimulated superoxide production by neutrophils, but significantly and dose-dependently suppressed agonist-stimulated superoxide production by monocytes. This suppression was not due to cell death. Chemical analysis identified the water-soluble components to be terpinen-4-ol, alpha-terpineol and 1,8-cineole. When examined individually, terpinen-4-ol significantly suppressed fMLP- and LPS- but not PMA-stimulated superoxide production; alpha-terpineol significantly suppressed fMLP-, LPS- and PMA-stimulated superoxide production; 1,8-cineole was without effect. CONCLUSION: Tea tree oil components suppress the production of superoxide by monocytes, but not neutrophils, suggesting the potential for selective regulation of cell types by these components during inflammation.

Anti-Infective Agents, Local↗

[Depression in Hashimoto's encephalopathy. Successful treatment of a severe depressive episode with a glucocorticoid as an add-on therapy].

Characteristic clinical findings of Hashimoto's encephalopathy (HE) are stroke-like episodes, epileptic seizures, myoclonus, psychosis, and progressive cognitive impairment. Diagnosis of HE is supported by elevated antithyroid antibodies, an abnormal EEG, and by good response to steroids. We report on a 74-year-old female patient with a severe depressive episode who showed no treatment response to citalopram 40 mg/day and venlafaxine 150 mg/day. Diagnostic examination revealed an abnormal EEG, elevated thyroid peroxidase antibodies (TPO-Ab), and older postinflammatory changes in thyroidal sonography. We diagnosed a depression in HE and began treatment with prednisolone 70 mg/day with stepwise dose reduction, continuing treatment with venlafaxine 150 mg/day. Within 4 weeks of treatment, the severe depressive episode disappeared as well as abnormal EEG. In addition, serum values of TPO-Ab decreased. In HE, depressive symptoms can possibly be seen in a subgroup of patients or in the early course of the disease. Diagnosis of HE should be included in diagnostic procedures in cases of therapy-refractory depression because of a good response of HE to steroids.

Aged↗

[Social anxiety disorders].

A main feature of social anxiety disorders is the fear or avoidance of social situations in which one is the center of attention and fears criticism or negative judgement. According to current diagnostic systems, three types of these disorders can be classified: specific social phobia, generalised social phobia, and avoidant personality disorder. Social anxiety disorders are prevalent mental disorders (lifetime prevalence up to 13%). Other mental disorders often appear together with them. Following the criteria for evidence-based medicine, psychotherapeutic and pharmacologic interventions are described. Regarding psychotherapeutic approaches, the best results have been seen with cognitive-behavioural methods. Among psychopharmacologic treatments, selective serotonin reuptake inhibitors and the selective noradrenalin reuptake inhibitor Venlafaxin are the first-choice treatments.

Adrenergic Uptake Inhibitors↗

[Depressive disorders and antidepressive therapy. A comparison of neurology practice and psychiatric clinic].

It is a question of great importance when psychiatric patients should be treated as inpatients or as outpatients. This decision depends on therapeutic as well as economic considerations. However in depression, as in other mental illnesses, many cases could reasonably be treated as in- or outpatients alike. Despite the importance of this question, there is to our knowledge no epidemiological study which compares patients in inpatient and outpatient settings within the current German medical system. 1300 inpatients and 5376 outpatients were investigated using identical methodologies within a drug utilization study of the antidepressant venlafaxine. Inpatients were found to be more severely ill and have a recurrent course of illness and higher rates of comorbidity. Outpatients more often had a chronic course. Inpatients were treated more often and with a wider variety of medication than outpatients, with the exception of phytopharmaceuticals. Venlafaxine was given in higher doses in the inpatient setting and combined more often with other psychotropic medications. Complaints of adverse drug reactions were comparable in both groups. Nausea was the most frequent, reported by 9.7% of inpatients and 15.2% of outpatients. The data show that the distribution of patients in outpatient and inpatient settings corresponds to the stepwise structure of the German health care system.

Adult↗

Serotonergic antidepressants and urinary incontinence.

Many new serotonergic antidepressants have been introduced over the past decade. Although urinary incontinence is listed as one side effect of these drugs in their package inserts there is only one report in the literature. This concerns 2 male patients who experienced incontinence while taking venlafaxine. In the present paper the authors describe 2 female patients who developed incontinence secondary to the selective serotonin reuptake inhibitors paroxetine and sertraline, as well as a third who developed this side effect on venlafaxine. In 2 of the 3 cases the patients were also taking lithium carbonate and beta-blockers, both of which could have contributed to the incontinence. Animal studies suggest that incontinence secondary to serotonergic antidepressants could be mediated by the 5HT4 receptors found on the bladder. Further research is needed to delineate the frequency of this troubling side effect and how best to treat it.

Adult↗

The peripheral sympathetic nervous system is the major target of cannabinoids in eliciting cardiovascular depression.

Our objective was to identify the sites of interaction of cannabinoids with cardiovascular sympathetic regulation in the rat. Effects on sympathetic tone were first determined in anaesthetised animals following i.v. administration of the drugs. Central effects were evaluated in anaesthetised rats receiving microinjections of cannabinoids into brain stem nuclei. Peripheral effects were identified in pithed rats with electrically stimulated sympathetic outflow. In anaesthetised and artificially ventilated rats, i.v. injection of the cannabinoid agonists WIN55212-2 and CP55940 decreased mean arterial pressure, heart rate and the plasma noradrenaline concentration. These effects were antagonized by the CB(1) cannabinoid receptor antagonist SR141716A. The bradycardia was abolished by the muscarinic acetylcholine receptor antagonist methylatropine. The decreases in mean arterial pressure and heart rate caused by cannabinoids in ventilated rats were much less pronounced than in spontaneously breathing rats. Microinjection of WIN55212-2 into the nucleus tractus solitarii had no effect. Microinjected into the rostral ventrolateral medulla oblongata, WIN55212-2 lowered mean arterial pressure slightly without changing other parameters. In pithed rats, WIN55212-2 inhibited the increases in mean arterial pressure, heart rate and the plasma noradrenaline concentration evoked by electrical stimulation of the sympathetic outflow. Our results show that activation of CB(1) cannabinoid receptors induces sympathoinhibition and enhancement of cardiac vagal tone, leading to hypotension and bradycardia. Presynaptic inhibition of noradrenaline release from terminals of postganglionic sympathetic neurons is the major component of the sympathoinhibition, but an effect in the rostral ventrolateral medulla oblongata may also contribute. The cannabinoid-evoked cardiovascular depression depends strongly on the respiratory state of the animals.

Animals↗

Analysis of the respiratory effects of cannabinoids in rats.

The objective of the present study was to evaluate the respiratory effects of cannabinoids and their influence on cardiovascular homeostasis.In spontaneously breathing urethane-anaesthetised rats, intravenous injection of the two synthetic cannabinoid receptor agonists WIN55212-2 and CP55940 strongly and dose-dependently lowered mean arterial pressure, heart rate and the plasma noradrenaline concentration. The cardiovascular depressive effects were associated with a large decrease in respiratory rate, hypoxia, hypercapnia and blood acidosis. All depressor effects of WIN55212-2 were abolished by the selective CB(1) cannabinoid receptor antagonist SR141716A. The bradycardia elicited by WIN55212-2 was inhibited by the muscarinic acetylcholine receptor antagonist methylatropine. The natural agonist Delta(9)-tetrahydrocannabinol also elicited cardiovascular and respiratory depression. In contrast, WIN55212-3, an enantiomer of WIN55212-2 lacking affinity for cannabinoid receptors, had no effect. The cannabinoid-evoked decreases in blood pressure and heart rate were much more pronounced in spontaneously breathing than in artificially ventilated urethane-anaesthetised rats. In contrast, the plasma noradrenaline concentration was lowered equally in both preparations. Our results show that activation of CB(1) cannabinoid receptors not only induces cardiovascular depression, but also markedly impairs ventilation. The second major finding of the present study is that the respiratory depression evoked by cannabinoids largely amplifies the cardiovascular depression.

Anesthesia↗

Cannabinoid CB1 receptor-mediated inhibition of acetylcholine release in the brain of NMRI, CD-1 and C57BL/6J mice.

Cannabinoid CB1 receptors occur as presynaptic receptors producing inhibition of neurotransmitter release. To elucidate their physiological role, experiments on tissues from CB1 receptor knockout mice would be helpful. We studied whether CB1 receptor-mediated inhibition of acetylcholine release is detectable in the brain of NMRI mice and of CD-1 and C57BL/6J mice (the latter two strains representing the wild-type strains of the two CB1 receptor knockout mouse models). Brain slices preincubated with [3H]choline were superfused and tritium overflow was evoked electrically (3 Hz) or by introduction of Ca2+ into Ca2+-free K+-rich medium (35 mM) containing tetrodotoxin. The eletrically evoked tritium overflow from NMRI mouse hippocampal slices was inhibited (maximally by 60%) by the cannabinoid receptor agonists CP-55,940 and WIN 55,212-2 but not affected by WIN 55,212-3 (the inactive enantiomer of WIN 55,212-2; pEC50=7.9, 7.4 and <5.5). The concentration-response curve of WIN 55,212-2 was shifted to the right by the CB1 receptor antagonist SR 141716 (apparent pA2=8.6). Compared to hippocampal slices from NMRI mice, WIN 55,212-2 1 microM inhibited the electrically evoked overflow (1) from cortical slices from NMRI mice to a lesser extent and from striatal slices not at all, (2) from hippocampal slices from CD-1 and C57BL/6J mice to an identical extent and (3) from hippocampal slices from Sprague-Dawley rats to at least the same extent. SR 141716 0.32 microM abolished the effect of WIN 55,212-2 1 microM in hippocampal slices from NMRI, CD-1 and C57BL/6J mice and in cortical slices from NMRI mice. The electrically evoked tritium overflow from NMRI mouse hippocampal slices was also inhibited by the muscarinic receptor agonist oxotremorine (maximum effect of 85%; pEC50=6.5) and this effect was antagonized by the muscarinic receptor antagonist AF-DX 384 (apparent pA2=8.3). The Ca2+-evoked tritium overflow from NMRI mouse hippocampal slices was inhibited by WIN 55,212-2 in a manner sensitive to SR 141716. In conclusion, the cholinergic axon terminals of the NMRI mouse hippocampus are endowed with presynaptic CB1 receptors. Such receptors are also detectable in the hippocampus of CD-1 and C57BL/6J mice. The maximum extent of the CB1 receptor-mediated inhibition of acetylcholine release is lower than the maximum effect mediated via the autoreceptor.

Acetylcholine↗

Sustained administration of the antidepressant venlafaxine in rats: pharmacokinetic and pharmacodynamic findings.

Rats were administered venlafaxine (10 mg/kg per day) for 14 days by using subcutaneously implanted osmotic minipumps. The present study assessed the distribution of VEN in different compartments, whether the VEN concentration in the compartments correlated, the effect of VEN on dialysate monoamine levels and on the spontaneous open-field behavior, and possible relations between the pharmacokinetic and pharmacodynamic parameters. The venlafaxine level in serum after sustained treatment was about 25% of the concentration in brain parenchyma and much higher than in brain dialysate. There was a clear correlation between venlafaxine concentrations in blood and brain compartments. The sustained venlafaxine challenge resulted in higher neocortical concentration of serotonin and noradrenaline, lower 5-hydroxyindole-3-acetic acid levels and increased locomotor activity in the central part of the test arena as compared to controls. No correlations were found between the venlafaxine concentration and brain monoamine parameters or the open-field behaviors. We conclude that, although species differences in pharmacokinetic properties for venlafaxine between rat and man exist, the pharmacokinetic correlations found after sustained treatment add information to the in vivo nature of the drug. Also, more studies like the present need to be performed to find the pharmacokinetic/pharmacodynamic interrelations for drugs like VEN.

Animals↗