The selective serotonin-2A receptor antagonist M100907 reverses behavioral deficits in dopamine transporter knockout mice.
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A hyperdopaminergic state in humans has been hypothesized to contribute to the pathology of a number of psychiatric illnesses, including schizophrenia, bipolar disorder, and attention deficit hyperactivity disorder. Mice that display elevated synaptic levels of dopamine due to a genetically engineered deletion of the dopamine transporter (DAT) model behavioral deficits that simulate the above conditions. As novel treatment strategies for these disorders have focused on the serotonin (5-HT) 2A receptor, we determined the capacity of the highly selective 5-HT(2A) receptor antagonist M100907 to reverse behavioral deficits in DAT knockout (KO) mice. Prior to drug treatment, DAT KO mice exhibited increased levels of locomotor activity and highly linearized movement in a novel environment, as well as reduced prepulse inhibition (PPI) of acoustic startle, compared to wild-type littermates. Treatment with M100907 (0.3-1.0 mg/kg, but not 0.1 mg/kg) reversed locomotor deficits in DAT KO mice. Similarly, treatment with 1.0 mg/kg M100907 reversed the PPI deficits in DAT KO mice. These data indicate that selective 5-HT(2A) receptor antagonists, such as M100907, may represent a class of drugs that can be used to treat conditions in which a chronic, elevated dopaminergic tone is present and contributes to abnormal behavior and sensorimotor gating deficits. (+info)
3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors protect cortical neurons from excitotoxicity.
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3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitors, or statins, reduce the incidence of strokes and reduce infarct volume after cerebral ischemia in mice. Excitoxicity caused by overstimulation of glutamate receptors is a major cause of neuronal death after an ischemic brain insult. Experiments presented here explored whether statins protect cultured neurons from excitotoxic death caused by the glutamate receptor agonist NMDA. Treatment with statins preserved NMDA receptor-expressing cortical neurons and potently and substantially reduced lactate dehydrogenase release caused by exposure of embryonic mouse neocortical cultures to NMDA. The rank order of neuroprotective potency was rosuvastatin = simvastatin > atorvastatin = mevastatin > pravastatin, which is similar to the known rank order of potency for inhibition of the HMG-CoA reductase enzyme. Resistance of cultures to NMDA excitotoxicity developed after several days of statin exposure. Neuroprotection by rosuvastatin was coincident with a decrease in cell sterols and occurred with a similar potency as inhibition of cholesterol biosynthesis. Neuroprotection was substantially attenuated by cotreatment with either mevalonate or cholesterol and was mimicked by acute treatment with the cholesterol-extracting agent beta-cyclodextrin, suggesting that neuroprotection was mediated by depletion of a cellular pool of cholesterol because of the inhibition of cholesterol biosynthesis. These results suggest the possibility that, in addition to effects on cerebrovascular function, statins have the potential to render cortical neurons more resistant to NMDA-induced excitotoxic death as a result of changes in cell cholesterol homeostasis. (+info)
Serotonergic facilitation of synaptic activity in the developing rat prefrontal cortex.
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Previous studies have outlined an important role for serotonin (5-HT) in the development of synaptic connectivity and function in the cerebral cortex. In this study, we have examined the effects of 5-HT on synaptic function in prefrontal cortex at a time of intense synapse formation and remodelling. Whole-cell recordings in slices derived from animals aged postnatal (P) days 16-20 showed that administration of 5-HT induced a robust increase in synaptic activity that was blocked by CNQX but not by bicuculline. This 5-HT-induced increase in glutamate-mediated synaptic activity was pharmacologically heterogeneous as it was differentially inhibited by the receptor subtype-selective antagonists SB-269970, MDL 100907 and GR 113808 and thus involved 5-HT(7), 5-HT(2A) and 5-HT(4) receptors. These results, obtained in juvenile cortex, contrast with those seen in adults where the increase in spontaneous excitatory postsynaptic currents (sEPSCs) was mediated solely by 5-HT(2A) receptors. In developing cortex, activation of 5-HT(7), but not 5-HT(2A) or 5-HT(4) receptors, elicited a robust inward current. However, the facilitation of synaptic activity mediated by all three of these receptors involved increases in both the amplitude and frequency of sEPSCs and was blocked by TTX. These results are best interpreted as indicating that all three receptor subtypes increase synaptic activity by exciting neuronal elements within the slice. No evidence was found for a postsynaptic facilitation of synaptic currents by 5-HT. Together, these results show that the repertoire of electrophysiologically active 5-HT receptors in prefrontal cortex is developmentally regulated, and that 5-HT(7) and 5-HT(4) receptors play a previously unsuspected role in regulating synaptic activity in this region. (+info)
More Western hypercholesterolemic patients achieve Japan Atherosclerosis Society LDL-C goals with rosuvastatin therapy than with atorvastatin, pravastatin, or simvastatin therapy.
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BACKGROUND: Data from Western comparative trials suggest that rosuvastatin is more effective than atorvastatin, simvastatin, and pravastatin in helping hypercholesterolemic patients achieve US and European lipid-lowering guidelines. The purpose of this analysis was to assess the comparative efficacy of rosuvastatin in reducing low-density lipoprotein cholesterol (LDL-C) to levels recommended by the Japan Atherosclerosis Society (JAS). METHODS AND RESULTS: A post hoc analysis of data from 6 randomized, double-blind, active-controlled trials was conducted to evaluate the relative efficacy of rosuvastatin and comparator statins in helping patients achieve the LDL-C goals established by the JAS. The first 5 trials, prospectively designed for pooling, were originally conducted to compare the effects of rosuvastatin with either atorvastatin, simvastatin, or pravastatin in reducing lipid levels and helping patients achieve the LDL-C goals established by the National Cholesterol Education Program. The 6th trial was conducted with similar objectives, but in patients with heterozygous familial hypercholesterolemia (HeFH). Data from 2,139 hypercholesterolemic patients in the first 5 trials were pooled for analysis: rosuvastatin 5 mg (n=390) or 10 mg (n=389) vs atorvastatin 10 mg (n=393); rosuvastatin 5 mg (n=240) or 10 mg (n=226) vs simvastatin 20 mg (n=249) or pravastatin 20 mg (n=252). In the studies with atorvastatin as the comparator, JAS-defined LDL-C goals were reached by 67.2% of the rosuvastatin 5-mg group, 82.3% of the rosuvastatin 10-mg group, and 58.0% of the atorvastatin 10-mg group (p<0.001 for both rosuvastatin groups vs atorvastatin) at 12 weeks. Similarly, in the trials with pravastatin and simvastatin as comparators, the JAS LDL-C goals were reached by 77.5% of the rosuvastatin 5-mg group, 86.7% of the rosuvastatin 10-mg group, 45.2% of the pravastatin 20-mg group and 65.5% of the simvastatin 20-mg group (p<0.001 for both rosuvastatin groups vs pravastatin and simvastatin). In the trial of HeFH patients (n=433 for rosuvastatin, n=187 for atorvastatin), 31.9% of patients treated with rosuvastatin 20 mg achieved JAS LDL-C goals, compared with 17.6% of patients treated with atorvastatin 20 mg (p<0.001). CONCLUSIONS: Rosuvastatin has demonstrated clinical superiority over atorvastatin, pravastatin, and simvastatin in reducing LDL-C levels and in enabling patients to reach goals established by the JAS. (+info)
Metofluthrin: a potent new synthetic pyrethroid with high vapor activity against mosquitoes.
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(1R)-trans-Norchrysanthemic acid fluorobenzyl esters are synthesized and their structure-activity relationships are discussed. These esters show outstanding insecticidal activity against mosquitoes. In particular, the 2,3,5,6-tetrafluoro-4-methoxymethylbenzyl analog (metofluthrin) exhibits the highest potency, being approximately forty times as potent as d-allethrin in a mosquito coil formulation when tested against southern house mosquitoes (Culex quinquefasciatus). Metofluthrin also exhibits a significant vapor action at room temperature. (+info)
Statins in hypercholesterolaemia: a dose-specific meta-analysis of lipid changes in randomised, double blind trials.
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BACKGROUND: Statins alter lipid concentrations. This systematic review determined the efficacy of particular statins, in terms of their ability to alter cholesterol. REVIEW METHODS: PubMed, the Cochrane Library, references lists of reports, and reviews were searched (September 2001) for randomised, double blind trials of statins for cholesterol in trials of 12 weeks or longer. Mean change in total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides was calculated using pooled data for particular statins, and for particular doses of a statin. Pre-planned sensitivity analyses were used to determine the effects of initial concentration of total cholesterol, study duration, the effects of major trials, and effects in placebo versus active controlled trials. Information was not collected on adverse events. RESULTS: Different statins at a range of doses reduced total cholesterol by 17-35% and LDL-cholesterol by 24-49% from baseline. Lower doses of statins generally produced less cholesterol lowering, though for most statins in trials of 12 weeks or longer there was at best only a weak relationship between dose and cholesterol reduction. Duration of treatment and baseline total cholesterol concentration did not alter the amount of the benefit attained. CONCLUSIONS: Statins are effective medicines and confer benefit to patients in terms of primary and secondary prevention of coronary heart disease. Reductions in total cholesterol of 25% or more and LDL cholesterol of more than 30% were recorded for fixed doses of simvastatin 40 mg, atorvastatin 10 mg, and rosuvastatin 5 mg and 10 mg. (+info)
The effect of rosuvastatin on oestrogen & progestin pharmacokinetics in healthy women taking an oral contraceptive.
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AIMS: To assess the effect of rosuvastatin on oestrogen and progestin pharmacokinetics in women taking a commonly prescribed combination oral contraceptive steroid (OCS); the effect on endogenous hormones and the lipid profile was also assessed. METHODS: This open-label, nonrandomised trial consisted of 2 sequential menstrual cycles. Eighteen healthy female volunteers received OCS (Ortho Tri-Cyclen) on Days 1-21 and placebo OCS on Days 22-28 of Cycles A and B Rosuvastatin 40 mg was also given on Days 1-21 of Cycle B. RESULTS: Co-administration did not result in lower exposures to the exogenous oestrogen or progestin OCS components. Co-administration increased AUC[0-24] for ethinyl oestradiol (26%; 90% CI ratio 1.19-1.34), 17-desacetyl norgestimate (15%; 90% CI 1.10-1.20), and norgestrel (34%; 90% CI 1.25-1.43), and increased Cmax for ethinyl oestradiol (25%; 90% CI 1.17-1.33) and norgestrel (23%; 90% CI 1.14-1.33). The increases in exposure were attributed to a change in bioavailability rather than a decrease in clearance. Luteinizing and follicle-stimulating hormone concentrations were similar between cycles. There were no changes in the urinary excretion of cortisol and 6beta-hydroxycortisol. Rosuvastatin significantly decreased low-density lipoprotein cholesterol [-55%], total cholesterol [-27%], and triglycerides [-12%], and significantly increased high-density lipoprotein cholesterol[11%]. Co-administration was well tolerated. CONCLUSIONS: Rosuvastatin can be coadministered with OCS without decreasing OCS plasma concentrations, indicating that contraceptive efficacy should not be decreased. The results are consistent with an absence of induction of CYP3A4 by rosuvastatin. The expected substantial lipid-regulating effect was observed in this study, and there was no evidence of an altered lipid-regulating effect with OCS coadministration. (+info)
Randomized dose-response study of rosuvastatin in Japanese patients with hypercholesterolemia.
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Rosuvastatin is a novel statin that has been shown to produce large dose-dependent reductions in low-density lipoprotein cholesterol (LDL-C) in Western hypercholesterolemic patients. Rosuvastatin dose response was assessed in a randomized, double-blind phase II trial in which 112 Japanese patients with fasting LDL-C > 160 and < 220 mg/dl and triglycerides < 300 mg/dl received placebo or rosuvastatin 1, 2.5, 5, 10, 20, or 40 mg once daily for 6 weeks. LDL-C change from baseline showed a linear dose response (p < 0.0001 for slope of regression line) over the rosuvastatin dose range, with each doubling of dose producing an additional 5.12% reduction. Mean reductions (least-squares mean percentage change from baseline from ANOVA) in LDL-C were 35.8% to 66.0% and significantly different from placebo at all doses (p < 0.0001). Linear dose response was also observed for total cholesterol (TC) and apolipoprotein (apo) B, but not for triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), or apo A-I or A-II. Mean changes at 6 weeks were - 25.5 to - 45.1% for TC, - 16.0 to - 26.2% for TG, + 7.5 to + 12.8% for HDL-C, - 31.9 to - 57.8% for apo B, + 5.5 to + 10.0% for apo A-I, and + 0.4 to + 8.1% for apo A-II. Rosuvastatin was well tolerated. Although there was some suggestion of increased frequency of treatment-related adverse events at higher doses, there were no clear dose relationships in safety parameters. Only one patient withdrew from the study because of a treatment-related adverse event. No patients had clinically significant elevations in liver transaminases or creatine kinase. Rosuvastatin produces good dose-related reductions in LDL-C and beneficial changes in other lipid fractions in Japanese hypercholesterolemic patients and is well tolerated. (+info)