Lipid-modifying effects of rosuvastatin in postmenopausal women with hypercholesterolemia who are receiving hormone replacement therapy

OBJECTIVE

To evaluate the efficacy and safety of rosuvastatin in postmenopausal women with hypercholesterolemia who are receiving hormone replacement therapy (HRT) in a randomized, double-blind, placebo-controlled trial.

METHODS

After a 6-week dietary lead-in period, 135 postmenopausal women who had been taking a stable HRT regimen for at least 3 months were randomized to receive rosuvastatin 5 mg, 10 mg or placebo for 12 weeks. Fasting levels of low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), total cholesterol (TC), and triglycerides (TG) were assessed at weeks 0, 2, 6, 10, and 12; apolipoprotein (Apo) B and Apo A-I were measured at weeks 0 and 12.

RESULTS

Rosuvastatin 5 mg and 10 mg significantly reduced LDL-C by 38% (SE = 2.1) and 49% (SE = 2.1), respectively, compared with placebo (1% [SE = 2.1]; p < 0.001). TC, TG, Apo B, and all lipid ratios examined (LDL-C/HDL-C, TC/HDL-C, non-HDL-C/HDL-C, and Apo B/Apo A-I) were also reduced significantly by both rosuvastatin doses (p < 0.001). HDL-C levels increased significantly in the rosuvastatin groups (11% and 8% for 5 mg and 10 mg, respectively, vs. -0.5% for placebo; p < 0.001), as did Apo A-I levels (p < 0.05). The combination of rosuvastatin plus HRT was well tolerated with no apparent differences among treatments in the numbers or types of adverse events reported.

CONCLUSIONS

Rosuvastatin 5 mg or 10 mg once daily is a well-tolerated and highly efficacious lipid-lowering therapy in postmenopausal women receiving HRT.

Drug and alternative therapies for hyperlipidemia

The recent guidelines for detection and treatment of hypercholesterolemia together with specific therapeutic goals have stimulated interest in, and use of, lipid lowering agents. The last decade has seen an explosive growth in the drug discovery area which is now translating into clinical trials with many new lipid lowering agents. In addition, clinical trials assessing clinical outcomes and cost effectiveness are resulting in a changing approach to how current lipid lowering drugs are used, especially in terms of dosing and combination therapies. At present only four classes of lipid altering agents remain in wide use; bile acid binding resins, niacin, fibrates and HMG CoA reductase inhibitors. Although only a decade has passed since the first HMG CoA reductase inhibitor, lovastatin, entered clinical trials this group of compounds are not only the most widely used lipid lowering agents, but more than six such agents have been or are currently being developed. In addition to pharmacological therapies, there have been significant advances in the non-pharmacological treatment of hypercholesterolemia, the most important being LDL-receptor gene replacement and selective LDL-apheresis.

Lipoprotein changes with statins

The effects of statins and other lipid drugs are assessed by their ability to affect specific lipid fractions. Although there has been a great deal written abut the statins, most recent papers have focused on the comparative effects of the statins on triglycerides and high-density lipoprotein cholesterol, or have been concerned with the nonlipid effects of these drugs. In addition, some recent papers have focused on new parameters that may mediate cardiovascular risk, such as high-sensitivity C-reactive protein.

Bilateral cannula system for intracranial chemical microinjection in small animals

An easily constructed and inexpensive bilateral cannula assembly for microinjection of chemicals into neural tissue in small animals is described. It reduces problems sometimes encountered with commercially available units, making it useful in both research and teaching laboratory settings. Suggestions for implant procedures and modifications for use in unique applications are suggested.

A new injection technique for intracerebral drug administration in behaving animals

A new fluid pump and technique has been described for drug administration into either ventricles or directly into brain tissue of awake, freely behaving animals. The novel apparatus and procedures eliminate most of the common methodological obstacles to injecting nl volume amounts into freely moving animals.

A preliminary study suggests that nicotine and prefrontal dopamine affect cortico-striatal areas in smokers with performance feedback

Nicotine and tonic dopamine (DA) levels [as inferred by catechol-O-methyl tranferase (COMT) Val158Met genotype] interact to affect prefrontal processing. Prefrontal cortical areas are involved in response to performance feedback, which is impaired in smokers. We investigated whether there is a nicotine × COMT genotype interaction in brain circuitry during performance feedback of a reward task. We scanned 23 healthy smokers (10 Val/Val homozygotes, 13 Met allele carriers) during two fMRI sessions while subjects were wearing a nicotine or placebo patch. A significant nicotine × COMT genotype interaction for BOLD signal during performance feedback in cortico-striatal areas was seen. Activation in these areas during the nicotine patch condition was greater in Val/Val homozygotes and reduced in Met allele carriers. During negative performance feedback, the change in activation in error detection areas such as anterior cingulate cortex (ACC)/superior frontal gyrus on nicotine compared to placebo was greater in Val/Val homozygotes compared to Met allele carriers. With transdermal nicotine administration, Val/Val homozygotes showed greater activation with performance feedback in the dorsal striatum, area associated with habitual responding. In response to negative feedback, Val/Val homozygotes had greater activation in error detection areas, including the ACC, suggesting increased sensitivity to loss with nicotine exposure. Although these results are preliminary due to small sample size, they suggest a possible neurobiological mechanism underlying the clinical observation that Val/Val homozygotes, presumably with elevated COMT activity compared to Met allele carriers and therefore reduced prefrontal DA levels, have poorer outcomes with nicotine replacement therapy.

Evaluation and comparison of radio-, fluorescence, and enzyme-linked immunoassays for serum thyroxine

We have compared three analytical systems for the measurement of serum thyroxine: enzyme-linked immunoassay (EIA), fluorescent immunoassay (FIA) and a radioimmunoassay (RIA). These were evaluated with respect to their precision, accuracy, analytical sensitivity and sample throughput. The RIA is more sensitive than the EIA (10 microgram/L vs. 35 Ug/L. Both systems have excellent precision (X = 86 ug/L, C.V.RIA = C.V.EIA = 4.6%). Both the EIA and RIA demonstrate good accuracy with recovery of between 97-98% of added thyroxine. The FIA has an apparent sensitivity between that of the RIA and EIA (25 microgram/L), but a precision consistently lower than the other two systems (C.V. = 7.4%, X = 86 microgram/L). Patients' results by RIA compared well with those from EIA )r = 0.91, P less than 0.05), but a poor correlation was found with FIA (r = 0.865, P greater than 0.05). Although not fully automated, the EIA performed on the Abbott ABA-100 analyzer has a sample throughput equal to the automated RIA system (Micromedic, Concept 4).

Effects of heroin and cocaine on brain activity in rats using [1-14C]octanoate as a fast functional tracer

Brain activity was measured autoradiographically using [1-14C]octanoate (OCTO) as a fast functional tracer in rats receiving either saline, heroin or cocaine. Regional optical densities were normalized to a relative optical density index for comparisons of OCTO labeling between treatment groups. Heroin significantly increased labeling in the dentate gyrus and cocaine increased density in the anterior cingulate cortex, globus pallidus, hippocampus CA3-4, lateral septum, hypothalamus and ventral tegmentum. Heroin and cocaine induced significant, but opposing effects in medial cortex and bed nucleus of the stria terminalis. Both drugs decreased labeling density in the nucleus accumbens and piriform cortex, and increased density in the substantia nigra, subthalamus, medial septum, claustrum, lateral hypothalamus and hippocampus CA2. These results demonstrate the ability of the OCTO method to discriminate the brief metabolic effects of different drug classes, and suggest that heroin and cocaine may activate a common functional system in the brain.

Effects of continuous naloxone administration on ventral tegmental self-stimulation

Continuous subcutaneous administration of naloxone (3 mg/kg/h), shifted ventral tegmental self-stimulation rate-frequency curves to the right, without suppressing behavioral performance. In addition this chronic blockade of opioid receptors altered mu binding parameters in the hippocampus and olfactory tubercle of naloxone-treated animals. These findings speak to the role opioid peptides paly in the mediation of brain stimulation reward.

Effect of heroin-conditioned auditory stimuli on cerebral functional activity in rats

Cerebral functional activity was measured as changes in distribution of the free fatty acid [1-14C]octanoate in autoradiograms obtained from rats during brief presentation of a tone previously paired to infusions of heroin or saline. Rats were trained in groups of three consisting of one heroin self-administering animal and two animals receiving yoked infusions of heroin or saline. Behavioral experiments in separate groups of rats demonstrated that these training parameters imparts secondary reinforcing properties to the tone for animals self-administering heroin while the tone remains behaviorally neutral in yoked-infusion animals. The optical densities of thirty-seven brain regions were normalized to a relative index for comparisons between groups. Previous pairing of the tone to heroin infusions irrespective of behavior (yoked-heroin vs. yoked-saline groups) produced functional activity changes in fifteen brain areas. In addition, nineteen regional differences in octanoate labeling density were evident when comparison was made between animals previously trained to self-administer heroin to those receiving yoked-heroin infusions, while twelve differences were noted when comparisons were made between the yoked vehicle and self administration group. These functional activity changes are presumed related to the secondary reinforcing capacity of the tone acquired by association with heroin, and may identify neural substrates involved in auditory signalled conditioning of positive reinforcement to opiates.

Effects of probucol on plasma lipids, lipoproteins and parameters of high density lipoprotein metabolism

Eight patients with primary hypercholesterolemia were treated with probucol for 17 weeks. Plasma total cholesterol, low density lipoprotein (LDL)-cholesterol, and high density lipoprotein (HDL)-cholesterol decreased by 16.6, 15.0 and 25.7%, respectively, in response to probucol treatment. Plasma levels of apolipoprotein B and apolipoprotein A-I also decreased, while apolipoprotein A-II concentrations were unchanged. The decrease in HDL-cholesterol levels was associated with a reduction in HDL particle size. No changes in the plasma lecithin:cholesterol acyltransferase activity or mass occurred in response to probucol treatment. In contrast, a significant 25% increase in plasma cholesteryl ester and triglyceride transfer activity occurred following probucol treatment. There was a positive correlation (R = 0.94) between cholesterol ester and triglyceride transfer. We propose that the increase in lipid transfer activity may in part explain the changes in HDL concentration and size, as well as the previously reported effect probucol has on reducing atherosclerosis in animal models.

Nicotine addiction: Translational insights from circuit neuroscience

Contemporary neuroscience aims to understand how neuronal activity produces internal processes and observable behavioral states. This aim crucially depends on systems-level, circuit-based analyses of the working brain, as behavioral states arise from information flow and connectivity within and between discrete and overlapping brain regions, forming circuits and networks. Functional magnetic resonance imaging (fMRI), offers a key to advance circuit neuroscience; fMRI measures inter and intra- regional circuits at behaviorally relevant spatial-temporal resolution. Herein, we argue that cross-sectional observations in human populations can be best understood via mechanistic and causal insights derived from brain circuitry obtained from preclinical fMRI models. Using nicotine addiction as an exemplar of a circuit-based substance use disorder, we review fMRI-based observations of a circuit that was first shown to be disrupted among human smokers and was recently replicated in rodent models of nicotine dependence. Next, we discuss circuits that predispose to nicotine dependence severity and their interaction with circuits that change as a result of chronic nicotine administration using a rodent model of dependence. Data from both clinical and preclinical fMRI experiments argue for the utility of fMRI studies in translation and reverse translation of a circuit-based understanding of brain disease states. We conclude by discussing the future of circuit neuroscience and functional neuroimaging as an essential bridge between animal models and human populations to the understanding of brain function in health and disease.

Electrophoretic separation of high-density lipoprotein choelsterol evaluated and compared with the modified lipid research clinic procedure

We evaluated a new agarose-gel-electrophoretic procedure (Corning) (I) for separating and quantitating of high-density lipoprotein cholesterol (HDLC), comparing it with the modified Lipid Research Clinics (LRC) procedure (heparin 183 kilounits/L, MnCl2 92 mmol/L) (II). Method I was insensitive to an HDLC concentration of 50 mg/L, but gave a linear dose-response curve between 130 and 1200 mg/L. Method II is sensitive to 50 mg/L and linear from 50--1200 mg/L. The within-plate CV for the Corning method varied from 26.2% for an HDLC of 168 mg/L to 6.8% for 580 mg/L. Within-day between-plate CV for the Corning method ranged from 22.1% at 155 mg/L to 8.0% at 651 mg/L, compared to 3.0 and 0.8% for the modified LRC procedure. Between-day CV for method I was 20, 12.6, 4.3, and 3.5% for HDLC concentrations of 175, 435, 542, and 678 mg/L, respectively; for method II it was 14, 5, 3.5, and 2.6%, respectively. Analysis of HDLC in 100 patients by both procedures showed mean HDLC values to be significantly lower (mean + SD, 27.8 +/- 1.7 mg/L; p less than 0.001) by method I. In 46 patients with HDLC less than 450 mg/L, this difference was accentuated (mean + SD = 40.5 +/- 2.6 mg/L) and clinically significant. Electrophoretic methods offer a promising further alternative method for HDLC separation and quantitation, but the negative bias, present limited sensitivity, and lack of precision at less than 450 mg/L indicate that they are not yet optimal for routine clinical use for patients with values less than 450 mg/L.

Effect of drinking on angiotensin-II-induced shifts in regional cerebral blood flow in the rat

A map of brain regions affected by central administration of the octapeptide angiotensin II (AII) and that would further reflect the consequences of AII's well-known dipsogenic action was developed. Regional cerebral blood flow (rCBF) as an indicator of neuronal activity was measured in conscious rats shortly after an ICV bolus injection of 100 ng AII or saline vehicle (VEH). AII-treated animals were further subdivided into two groups that were either permitted to drink [AII (W+)] or whose water was removed when drinking was attempted [AII (W-)]. When compared to VEH condition, blood flow increased significantly within 1 min after AII treatment in 33 of 53 regions sampled in those rats not given an opportunity to drink. In 11 of these 33 regions, ingestion of a small amount of water was associated with a reversal of AII-induced elevation in blood flow [i.e., AII (W+) less than AII (W-)]; these regions included the organum vasculosum lamina terminalis, rostral lateral hypothalamus, supraoptic nuclei, rostral zona incerta, and median eminence. A group of similarly treated rats exhibited a significant elevation of mean arterial blood pressure following AII treatment without significant shifts in arterial blood gases, pH, or bicarbonate. These data are consistent with prominent involvement of the anteroventral third ventricular region of the rat brain. The results further indicate that rCBF may be a sensitive measure for the identification of central sites of action of AII as a dipsogenic agent and may reveal distinctions between regions associated primarily with initiation of drinking and those reflecting the results of subsequent behavioral events.

Effect of Pravastatin in the Treatment of Patients with Type III Hyperlipoproteinemia

OBJECTIVE: To determine the efficacy and safety of pravastatin in the treatment of subjects with Type III hyperlipoproteinemia. DESIGN: Randomized, double-blind, placebo-controlled, crossover study. SETTING: Four lipid research clinics in the United States. PATIENTS: Twenty subjects between 18 and 70 years old with three diagnostic features of Type III hyperlipoproteinemia: very-low-density lipoprotein cholesterol (VLDL-C)/total plasma triglyceride ratio in excess of 0.30; beta-migrating VLDL pattern on agarose-gel electrophoresis; and the homozygous apolipoprotein E phenotype E(2)/E(2). After 4 weeks of dietary control, the subjects were eligible if their mean plasma total cholesterol level was at least 250 mg/dl and mean plasma trigylceraide level was at least 220 mg/dL. INTERVENTIONS: Subjects were randomly assigned to pravastatin 40 mg hs or placebo hs at the start of the first 6-week double-blind treatment period. After completing this phase, subjects entered a 4-week placebo/drug washout phase before crossing over to the opposite treatment for the second 6-week double-blind treatment period. MEASUREMENTS: Plasma VLDL-C and low density lipoprotein cholesterol (LDL-C) after ultracentrifugation and total triglyceride, cholesterol and high-density lipoprotein cholesterol (HDL-C) after 6 weeks of treatment; adverse clinical events and abnormal laboratory results. RESULTS: After 6 weeks of pravastatin theraphy, plasma levels of VLDL-C and LDL-C decreased 49% and 39%, respectively (p less-than-or-equal 0.01 vs. placebo). Total cholesterol and triglyceride concentrations decreased 36% and 22%, respectively (p less-than-or-equal 0.001 vs. placebo). Levels of HDL-C increased 8% (p less-than-or-equal 0.01 vs. placebo). Pravastatin was tolerated well. One marked laboratory abnormality, an asymptomatic elevation of creatine phosphokinase, resolved upon completing pravastatin treatment. CONCLUSIONS: Pravastatin lowers plasma VLDL-C, LDL-C, total cholesterol, and triglyceride and raises HDL-C in subjects with Type III hyperlipoproteinemia. The safety profile is excellent. Pravastatin reductase inhibitor therapy affords a useful approach to the management of Type III or remnant removal disease.

Delayed emergence of methamphetamine's enhanced cardiovascular effects in nonhuman primates during protracted methamphetamine abstinence

BACKGROUND

Methamphetamine abuse is linked with brain abnormalities, but its peripheral effects constitute an integral aspect of long-term methamphetamine use.

METHODS

Eight male rhesus monkeys with long histories of intravenous methamphetamine self-administration were evaluated 1 day, and 1, 4, 12, 26, and 52 weeks after their last methamphetamine self-administration session. On test days, isoflurane-anesthetized animals received a 0.35 mg/kg IV methamphetamine challenge. A control group consisted of 10 age and gender matched drug naïve monkeys. Cardiovascular responses to methamphetamine were followed for 2.5h. Echocardiograms were acquired at 3 and 12 months of abstinence and in the control animals.

RESULTS

No pre-methamphetamine baseline differences existed among 7 physiological measures across all conditions and controls. As expected, methamphetamine increased heart rate and blood pressure in controls. However, immediately following the self-administration period, the blood pressure response to methamphetamine challenge was reduced when compared to control monkeys. The peak and 150-min average heart rate increases, as well as peak blood pressure increases following methamphetamine were significantly elevated between weeks 12 to 26 of abstinence. These data indicate the development of tolerance followed by sensitization to methamphetamine cardiovascular effects. Echocardiography demonstrated decreased left ventricular ejection fraction and cardiac output at 3 months of abstinence. Importantly, both cardiovascular sensitization and cardiotoxicity appeared to be reversible as they returned toward control group levels after 1 year of abstinence.

CONCLUSIONS

Enhanced cardiovascular effects may occur after prolonged abstinence in addicts relapsing to methamphetamine and may underlie clinically reported acute cardiotoxic events.