Cannabinol enhancement of interleukin-2 (IL-2) expression by T cells is associated with an increase in IL-2 distal nuclear factor of activated T cell activity.
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It has been demonstrated previously that cannabinol (CBN) differentially modulates interleukin-2 (IL-2) protein secretion by T cells with a corresponding change in extracellular signal-regulated kinase activity. The objective of the present studies was to further investigate the molecular mechanism by which CBN enhances IL-2 gene expression using the EL4 T cell line. We demonstrate here that steady-state IL-2 mRNA expression was significantly enhanced by CBN in a concentration-dependent manner in EL4 cells activated with suboptimal concentrations of phorbol-12-myristate-13-acetate (2-10 nM). Concordantly, a marked increase was observed in nuclear factor of activated T cells (NF-AT) DNA binding activity to the IL-2 distal NF-AT site, but not to nuclear factor for immunoglobulin kappa chain in B cells or activator protein 1 motifs. Transient transfection of EL4 cells with a reporter gene under the control of multiple IL-2 distal NF-AT motifs exhibited increased transcriptional activity by CBN in suboptimally activated cells. In addition, the CBN-mediated enhancement of IL-2 protein secretion and the transcriptional activity of the IL-2 distal NF-AT reporter gene was abrogated by the calcium/calmodulin-dependent protein kinase inhibitor KN93, but not by the CB2 receptor antagonist SR144528. Enhancement of IL-2 was also demonstrated with CP55940, Delta(9)-tetrahydrocannabinol, and cannabidiol, thus suggesting that the phenomenon is not unique to CBN. Collectively, these results suggest that increased IL-2 secretion by CBN is mediated through the enhancement of IL-2 gene transcription by activation of NF-AT in a CB1/CB2-independent manner. (+info)
Distribution of venlafaxine and its O-desmethyl metabolite in human milk and their effects in breastfed infants.
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AIMS: To characterize milk/plasma (M/P) ratio and infant dose, for venlafaxine (V) and its O-desmethyl metabolite (ODV), in breastfeeding women taking venlafaxine for the treatment of depression, and to determine the plasma concentration and effects of these drugs in their infants. METHODS: Six women (mean age 34.5 years, mean weight 84.3 kg) taking venlafaxine (median dose 244 mg day(-1), range 225-300 mg day(-1)) and their seven infants (mean age 7.0 months, mean weight 7.3 kg) were studied. V and ODV in plasma and milk were measured by high-performance liquid chromatography over a 12 h dose interval at steady-state. Infant exposure was estimated as the product of estimated milk production rate (0.15 l kg(-1)day(-1)) and average drug concentration in milk, normalized to body weight and expressed as a percentage of the weight-adjusted maternal dose. RESULTS: Mean M/PAUC values of 2.5 (range 2.0-3.2) and 2.7 (range 2.3-3.2) were calculated for V and ODV, respectively. The mean maximum concentrations (95% CI) of V and ODV in milk were 1161 (95% CI, 588, 1734) microg l(-1) and 796 (362, 1230) microg l(-1). Mean infant exposure was 3.2% (1.7, 4.7%) for V and 3.2% (1.9, 4.9%) for ODV (as V equivalents). V was detected in the plasma of one out of seven infants studied (5 microg l(-1)), while ODV was detected in four of the infants, at concentrations ranging from 3 to 38 microg l(-1). All of the infants in the study were healthy, as reported by their mothers and/or by clinical examination on the study day. CONCLUSIONS: The concentrations of V and ODV in breast milk were 2.5 and 2.7 times those in maternal plasma. The mean total drug exposure (as venlafaxine equivalents) of the breastfed infants was 6.4% (5.5-7.3%), which is below the 10% notional level of concern. There were no adverse effects in any of the infants. The data support the use of V in breastfeeding. Nevertheless, since low concentrations of ODV were detected in the plasma of four out of the seven infants studied, we recommend breastfed infants should be monitored closely. Each decision to breast feed should be made as an individual risk:benefit analysis. (+info)
Proconvulsant effects of high doses of venlafaxine in pentylenetetrazole-convulsive rats.
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Venlafaxine, an atypical antidepressant drug, has been used to treat several neurological disorders, presenting excellent efficacy and tolerability. Clinical seizures after venlafaxine treatment have occasionally been reported when the drug was used at very high doses or in combination with other medications. The aim of the present study was to investigate the convulsant effects of venlafaxine in rats under controlled laboratory conditions. Adult male Wistar rats (8 per group) receiving venlafaxine or saline at the doses of 25-150 mg/kg were subjected 30 min later to injections of pentylenetetrazole at the dose of 60 mg/kg. The animals receiving 75, 100 and 150 mg/kg venlafaxine presented increased severity of convulsion when compared to controls (P = 0.02, P = 0.04, and P = 0.0004, respectively). Indeed, an increased percentage of death was observed in these groups (50, 38, and 88%, respectively) when compared to the percentage of death in the controls (0%). The group receiving 150 mg/kg showed an reduction in death latency (999 +/- 146 s) compared to controls (1800 +/- 0 s; cut-off time). Indeed, in this group, all animals developed seizures prior to pentylenetetrazole administration. Surprisingly, the groups receiving venlafaxine at the doses of 25 and 50 mg/kg showed a tendency towards an increase in the latency to the first convulsion. These findings suggest that venlafaxine at doses of 25 and 50 mg/kg has some tendency to an anticonvulsant effect in the rat, whereas doses of 75, 100 and 150 mg/kg presented clear proconvulsant effects in rats submitted to the pentylenetetrazole injection. These findings are the first report in the literature concerning the role of venlafaxine in seizure genesis in the rat under controlled conditions. (+info)
Efficacy and tolerability of venlafaxine compared with selective serotonin reuptake inhibitors and other antidepressants: a meta-analysis.
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BACKGROUND: In individual studies and limited meta-analyses venlafaxine has been reported to be more effective than comparator antidepressants, particularly selective serotonin reuptake inhibitors (SSRIs). AIMS: To perform a systematic review of all such studies. METHOD: We conducted a systematic review of double-blind, randomised trials comparing venlafaxine with alternative antidepressants in the treatment of depression. The primary outcome was the difference in final depression rating scale value, expressed as a standardised effect size. Secondary outcomes were response rate, remission rate and tolerability. RESULTS: A total of 32 randomised trials were included. Venlafaxine was more effective than other antidepressants (standardised effect size was -0.14, 95% Cl -0.07 to -0.22). A similar significant advantage was found against SSRIs (20 studies) but not tricyclic antidepressants (7 studies). CONCLUSIONS: Venlafaxine has greater efficacy than SSRIs although there is uncertainty in comparison with other antidepressants. Further studies are required to determine the clinical importance of this finding. (+info)
Does combined treatment with novel antidepressants and a dopamine D3 receptor agonist reproduce cocaine discrimination in rats?
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It is established that dopamine (DA) neurotransmission plays a critical role in the behavioral (e.g. discriminative stimulus) effects of cocaine in rodents. Nonetheless, research has also demonstrated that reciprocal signaling between DA and monoamine neurotransmitters, i.e. serotonin (5-HT) and norepinephrine (NE) has important implication for understanding the actions of cocaine. The present study was focussed on the ability of novel antidepressant drugs (milnacipram, reboxetine and venlafaxine), which affect either NE or both 5-HT and NE reuptake mechanism, to alter (enhance or antagonize) the discriminative stimulus effects of cocaine. Moreover, we investigated if the combined treatment with those drugs and a DA D3 receptor agonist (pramipexole) could reproduce cocaine discrimination. Male Wistar rats were trained to discriminate cocaine (10 mg/kg, ip) from saline (ip) in a two-choice, water-reinforced fixed-ratio 20 drug discrimination paradigm. Given alone, none of antidepressant drugs induced substitution for the cocaine-lever responses. Pramipexole (0.25 mg/kg) produced a partial substitution for cocaine (i.e. 43-52% cocaine-lever responding). In combination experiments, milnacipram (10 mg/kg) or reboxetine (10 mg/kg) given with submaximal doses of cocaine (1.25-5 mg/kg) did not affect the cocaine dose-response curve or its ED50 values. Venlafaxine (10 mg/kg) given in combination with submaximal doses of cocaine (0.6-5 mg/kg) produced significant enhancement of cocaine discrimination with a leftward shift in the cocaine dose-response curve and a decrease in its ED50 value. Pretreatment with either milnacipram (10 mg/kg) or reboxetine (10 mg/kg) failed to modulate the partial substitution evoked by pramipexole (0.25 mg/kg). On the other hand, venlafaxine (10 mg/kg) given in combination with a submaximal dose of pramipexole (0.25 mg/kg), which separately elicited 16 and 42% the cocaine-lever responses, produced significant enhancement of cocaine discrimination (up to 99% of the drug-lever responding). These results indicate that the discriminative stimulus effects of cocaine in rats can be enhanced by venlafaxine or mimicked by the combination with this antidepressant drug and the DA D3 receptor agonist. This finding, together with the recent data reporting the lack of rewarding properties of venlafaxine and the attenuation of morphine dependence and withdrwal signs in rats by the drug, may indicate a possible therapeutic use of this antidepressant in cocaine abuse. (+info)
Early changes in prefrontal activity characterize clinical responders to antidepressants.
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Previous studies have shown that changes in brain function precede clinical response to antidepressant medications. Here we examined quantitative EEG (QEEG) absolute and relative power and a new measure, cordance, for detecting regional changes associated with treatment response. Fifty-one adults with unipolar depression completed treatment trials using either fluoxetine or venlafaxine vs. placebo. Data were recorded at baseline and after 48 h and 1 week on drug or placebo. Baseline and change from baseline values were examined for specific brain regions in four subject groups (medication and placebo responders and nonresponders). No regional baseline QEEG differences were found among the groups; there also were no significant changes in theta power over time. In contrast, medication responders uniquely showed significant decreases in prefrontal cordance at 48 h and 1 week. Clinical differences did not emerge until after four weeks. Subjects with greater changes in cordance had the most complete 8-week responses. These findings implicate the prefrontal region in mediating response to antidepressant medications. Cordance may have clinical applicability as a leading indicator of individual response. (+info)
Characterization of the diarylether sulfonylester (-)-(R)-3-(2-hydroxymethylindanyl-4-oxy)phenyl-4,4,4-trifluoro-1-sulfonate (BAY 38-7271) as a potent cannabinoid receptor agonist with neuroprotective properties.
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(-)-(R)-3-(2-Hydroxymethylindanyl-4-oxy)phenyl-4,4,4-trifluoro-1-sulfonate (BAY 38-7271) is a new high-affinity cannabinoid receptor subtype 1 (CB1 receptor) ligand (K(i) = 0.46-1.85 nM; rat brain, human cortex, or recombinant human CB1 receptor), structurally unrelated to any cannabinoid receptor ligand known so far. BAY 38-7271 was characterized as a CB1 receptor agonist in 5-[gamma(35)S]-thiophosphate triethylammonium salt binding assays using rat or human CB1 receptors. In the rat hypothermia assay, BAY 38-7271 induced a dose-dependent reduction in body temperature (minimal effective dose = 6 microg/kg, i.v.); whereas in rats trained to discriminate the CB1/CB2 receptor agonist (-)-cis-3-[2-hydroxy-4(1,1-dimethyl-heptyl)phenyl]-trans-4-(3-hydroxypropyl) cyclohexanol (CP 55,940; 0.03 mg/kg, i.p.) from vehicle, BAY 38-7271 induced complete generalization (3 microg/kg, i.v.). In both in vivo models, a specific CB1 receptor-mediated mechanism was confirmed by demonstrating that the effects of CP 55,940 and BAY 38-7271 were blocked by pretreatment with the selective CB1 receptor antagonist N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole -3-carboxamidehydrochloride. In the rat traumatic brain injury model, BAY 38-7271 demonstrated highly potent and efficient neuroprotective properties when administered as a 4-h infusion immediately after induction of subdural hematoma (70% infarct volume reduction at 100 ng/kg/h). Even when applied with a 3-h delay, a significant neuroprotective efficacy could be observed (59% infarct volume reduction at 300 ng/kg/h). The neuroprotective potential of BAY 38-7271 was confirmed in a rat model of focal cerebral ischemia induced by permanent occlusion of the middle cerebral artery. It is concluded that the CB1/CB2 receptor agonist BAY 38-7271 shows pronounced neuroprotective properties that do not result from drug-induced hypothermia and that occur in a dose range devoid of typical cannabinoid-like side effects. (+info)
Role of the endocannabinoid system in MDMA intracerebral self-administration in rats.
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I.c.v. self-administration of MDMA (0.01-2 micro g per infusion), alone and in combination with CP 55,940 (0.4 micro g infusion(-1)), was studied on an operant responding procedure. On the basis of individual preference for one of two levers, developed during training, rats were allowed to self-administer vehicle from the preferred lever and MDMA from the other. Pressings on the MDMA associated-lever, except for the maximal unit dose, progressively increased. The combination of CP 55,940 with MDMA (1 micro g infusion(-1)) reduced the number of drug-associated lever pressings compared to the single drugs. Pre-treatment with SR 141716A (0.5 mg kg(-1) i.p.), 15 min before each daily session, significantly increased MDMA self-administration. These findings suggest that MDMA self-administration is under endogenous tonic control by the endocannabinoid system. (+info)