Selective serotonin reuptake inhibitors fluvoxamine and paroxetine restore forced exercise-induced temperature dysregulation in ovariectomized mice

Hot flushes are one of the most frequent symptoms in menopausal women. Selective serotonin reuptake inhibitors (SSRIs) are considered to be first-line therapy for the treatment of hot flushes in women for whom hormone therapy is contraindicated. Recently, we have proposed forced exercise-induced flushing of tail skin in ovariectomized mice as a new experimental model of temperature dysregulation in menopausal hot flushes. In the present study, to validate this animal model as a tool for testing potential compounds for the treatment of menopausal hot flushes, we examined the effects of two SSRIs (fluvoxamine and paroxetine) on forced exercise-induced flushing of tail skin in ovariectomized mice, and compared it with that of estradiol replacement (1 mg/kg/week for 3 weeks, i.m.). Treatment with fluvoxamine (20 mg/kg, i.p.) or paroxetine (10 mg/kg, i.p.) completely inhibited forced exercise-induced flushing of tail skin in ovariectomized mice, and the effect of each was comparable to that of estradiol replacement. It is believed that the present findings provide the first experimental evidence to support the anti-flushing effects of SSRIs, such as fluvoxamine and paroxetine, in a clinical setting. An animal model with forced exercise probably serves as a useful experimental tool for evaluating the effects of different agents on hot flushes.     

The safety of veralipride

The perimenopausal period, from 1 to 4 years, is characterised by vasomotor symptoms, or hot flushes, and other effects due a deficit of estrogens. Approximately 85% of women have hot flushes for 1 year and 25 – 50% continue for up to 5 years. The cause of hot flushes has been linked to dysfunction of the thermoregulatory centre caused by estrogen withdrawal. One proposal for the aetiology of hot flushes is that the thermoregulatory zone is shifted downward in patients who experience hot flushes. Estrogen withdrawal creates a change of the central opioid system and a thermoregulatory instability. Estrogen and/or progestin replacement is the treatment of choice for this distressing symptom. However, steroid replacement may be associated with risks and complications, and is limited in some subjects by well-known contraindications. Veralipride, a synthetic benzamide derivative with antidopaminergic action, is effective in reducing the frequency and severity of hot flushes associated with menopausal hypoestrogenism, gaining interest as a non-hormonal treatment for climacteric flushing. In recent years, extrapyramidal disorders associated with veralipride therapy have been reported and are often due to drug misuse. Adverse effects include acute dyskinesia or Parkinsonism, which may occur after many months of treatment. An association between adverse effects and mistake of administration has been described. This article discusses available data on the benefits and risks of veralipride therapy for menopausal symptoms.     

The safety of veralipride

The perimenopausal period, from 1 to 4 years, is characterised by vasomotor symptoms, or hot flushes, and other effects due a deficit of estrogens. Approximately 85% of women have hot flushes for 1 year and 25 - 50% continue for up to 5 years. The cause of hot flushes has been linked to dysfunction of the thermoregulatory centre caused by estrogen withdrawal. One proposal for the aetiology of hot flushes is that the thermoregulatory zone is shifted downward in patients who experience hot flushes. Estrogen withdrawal creates a change of the central opioid system and a thermoregulatory instability. Estrogen and/or progestin replacement is the treatment of choice for this distressing symptom. However, steroid replacement may be associated with risks and complications, and is limited in some subjects by well-known contraindications. Veralipride, a synthetic benzamide derivative with antidopaminergic action, is effective in reducing the frequency and severity of hot flushes associated with menopausal hypoestrogenism, gaining interest as a non-hormonal treatment for climacteric flushing. In recent years, extrapyramidal disorders associated with veralipride therapy have been reported and are often due to drug misuse. Adverse effects include acute dyskinesia or Parkinsonism, which may occur after many months of treatment. An association between adverse effects and mistake of administration has been described. This article discusses available data on the benefits and risks of veralipride therapy for menopausal symptoms.     

Forced exercise-induced flushing of tail skin in ovariectomized mice, as a new experimental model of menopausal hot flushes

Hot flushes are the most common complaint of menopausal women. In the present study, a new animal model of hot flushes was established. Tail skin temperature was measured with a thermo tracer after mice were subjected to a forced exercise task using a motor driven treadmill. In ovariectomized mice, forced exercise for 10 min was most effective in increasing tail skin temperature over that of sham-operated mice. This elevation was blocked by estradiol replacement (1 mg/kg per week for 3 weeks), suggesting that our model simulates menopausal hot flushes.     

Soybean isoflavones eliminate nifedipine-induced flushing of tail skin in ovariectomized mice

Hot flushes are one of the most frequent symptoms in menopausal women. We investigated effect of soybean isoflavones (Soyaflavone HG) on nifedipine-induced flushing in ovariectomized mice. Ovariectomy markedly aggravated nifedipine-induced increase in tail skin temperature. Soyaflavone HG (10 mg/kg, p.o., once a day for 5 days) inhibited nifedipine-induced flushing in ovariectomized mice. The inhibitory effect of Soyaflavone HG was significantly reversed by an estrogen-receptor antagonist, ICI 182,780, suggesting that Soyaflavone HG prevents nifedipine-induced flushing partially through estrogen receptors. We presented the experimental evidence suggesting that soybean isoflavones including Soyaflavone HG have the benefits for menopausal hot flushes.     

Molecular mechanism of vasorelaxant and antiatherogenic effects of the statins in the human saphenous vein graft

In this study we aimed to investigate the vasorelaxant and antiatherogenic effects of the statins (fluvastatin and pravastatin) in the human saphenous vein grafts at the molecular level by using histopathologic, pharmacological and immunochemical techniques. The saphenous vein grafts evaluated histopathologically displayed a loss in their endothelium up to a ratio of 30% and set forth indications of functional deterioration. The pharmacological evaluations proved that the relaxation responses induced by fluvastatin and pravastatin were significantly inhibited by nitric oxide synthase inhibitor, N(G)-nitro-l-arginine, and cyclooxygenase inhibitor, indomethacin, while these responses were significantly increased by angiotensin converting enzyme inhibitors, captopril and enalapril, and rho kinase inhibitor, Y27632. The results of immunochemical studies are in accordance with the results of the pharmacological studies that the related statins increased the levels of nitric oxide, phospholipase A(2) and they decreased the levels of angiotensin II and active rho kinase. On the other hand mevalonolactone, a substrate of lipid metabolism, failed to change the effects of fluvastatin and pravastatin in the related tissue. The experimental results indicate that activation of nitric oxide synthase and phospholipase A(2)-cyclooxygenase pathway and inhibition of angiotensin converting enzyme and rho kinase may have a role on the effects of fluvastatin and pravastatin in the human saphenous vein grafts. It seems that the vasorelaxant and antiatherogenic effects of the related statins are independent of their lipid lowering mechanism.     

Effect of 3-hydroxy-3-methylglutarylcoenzyme A reductase inhibitors (statins) on tissue paraoxonase 1 and plasma platelet activating factor acetylhydrolase activities

The authors investigated the effect of pravastatin and fluvastatin on paraoxonase 1 (PON1) activity in plasma, liver, heart, and kidney, as well as on plasma platelet activating factor acetylhydrolase (PAF-AH) in the rat. The animals received pravastatin at doses of 4 and 40 mg/kg/d or fluvastatin at doses of 2 or 20 mg/kg/d for 3 weeks. Fluvastatin (20 mg/kg/d) reduced plasma PON1 activity toward paraoxon and phenyl acetate by 23.6% and 17.4%, respectively. The lower dose of this drug as well as both doses of pravastatin had no effect on plasma PON1. PON1 activity toward paraoxon in the liver of rats treated with 20 mg/kg/d fluvastatin was 27.5% lower than in the control group, and the activity toward phenyl acetate was reduced by 25.4% and 35.9% in rats receiving 2 and 20 mg/kg/d of this drug, respectively. Fluvastatin at 2 and 20 mg/kg/d also decreased cardiac PON1 by 31.3% and 27.3%, respectively. Both statins reduced PON1 activity in the renal cortex and medulla. Statins had no effect on plasma PAF-AH. It is concluded that fluvastatin reduces PON1 activity more efficiently than does pravastatin. Reducing effect on PON1 may negatively modulate atheroprotective potential of statins and may contribute to differences in antiatherosclerotic properties of different drugs in this group.     

The effect of gliclazide and glibenclamide on preconditioning of the human myocardium

The purpose of this study was to evaluate the role of estrogen as a vasodilator or relaxing modulator during vascular tonus through chronic estrogen treatment. Experiments were conducted using isolated basilar arteries from ovariectomized female rabbits divided into two groups (the with and without estrogen replacement groups, respectively). Both acetylcholine and carbachol relaxed the basilar arteries of rabbits in the with estrogen replacement group (pre-contracted by 30 mM K⁺) more strongly than in the without estrogen replacement group. Vasodilatation effects of (±)-(E)-4-methyl-2-[(E)-hydroxyimino]-5-nitro-6-methoxy-3 -hexenamide (NOR1) and S-nitroso-N-acetyl-penicillamine (SNAP) were greater in rabbits in the with estrogen replacement group than the without estrogen replacement both with endothelium-intact and denuded preparations. On the other hand, vasodilatation effects of nicardipine, 17β-estradiol and membrane-permeable cyclic-GMP or cyclic-AMP were the same in both groups. These results suggest that chronic administration of estradiol potentiates reactivity to nitric oxide (NO) in smooth muscle cells, which could be a therapeutic target for cardiovascular diseases in postmenopausal women.     

Effects of fluvastatin on endothelium-derived hyperpolarizing factor- and nitric oxide-mediated relaxations in arteries of hypertensive rats

Endothelial cells release endothelium-derived hyperpolarizing factor (EDHF), as well as nitric oxide (NO). It has recently been suggested that 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) improve NO-mediated endothelial function, partially independently of their cholesterol-lowering effects. It is, however, unclear whether statins improve EDHF-mediated responses. Eight-month-old stroke-prone spontaneously hypertensive rats (SHRSP) were treated with fluvastatin (10 mg/kg per day) for 1 month. Age-matched, normotensive Wistar Kyoto (WKY) rats served as controls. Both EDHF- and NO-mediated relaxations were impaired in SHRSP compared with WKY rats. Fluvastatin treatment did not affect blood pressure and serum total cholesterol. The acetylcholine (ACh)-induced, EDHF-mediated hyperpolarization in mesenteric arteries did not significantly differ between fluvastatin-treated SHRSP and untreated SHRSP and the responses in both groups were significantly smaller compared with those of WKY rats. Endothelium-derived hyperpolarizing factor-mediated relaxations, as assessed by the relaxation to ACh in mesenteric arteries contracted with noradrenaline in the presence of N(G)-nitro-l-arginine and indomethacin, were virtually absent and similar in both SHRSP groups. In contrast, NO-mediated relaxation, as assessed by the relaxation in response to ACh in rings contracted with 77 mmol/L KCl, was improved in fluvastatin-treated SHRSP compared with untreated SHRSP (maximum relaxation in control and fluvastatin groups 42.0 +/- 5.2 and 61.2 +/- 3.8%, respectively; P < 0.05). Hyperpolarization and relaxation in response to levcromakalim, an ATP-sensitive K(+) channel opener, were similar between the two SHRSP groups. These findings suggest that fluvastatin improves NO-mediated relaxation, but not EDHF-mediated hyperpolarization and relaxation, in SHRSP. Thus, the beneficial effects of the statin on endothelial function may be mainly ascribed to an improvement in the NO pathway, but not EDHF.     

Chronic treatment with fluvastatin improves smooth muscle dilatory function in genetically determined hyperlipoproteinemia

We hypothesized that the HMG-CoA reductase inhibitor fluvastatin, does not only improve endothelium-dependent vasorelaxation, but that it also increases vascular smooth muscle reactivity in hyperlipoproteinemia. New Zealand White (NZW) rabbits aged 37 weeks (control), Watanabe Heritable Hyperlipidemic rabbits (WHHL) aged 37 weeks, and WHHL aged 35 weeks with fluvastatin treatment of 17 weeks (10 mg/kg/d) were examined. Aortas were isolated for isometric tension recording. Both endothelium-dependent and independent relaxation were impaired in WHHL. Fluvastatin significantly restored impaired endothelium-independent relaxation (WHHL: 57 +/- 12 versus WHHL+ fluvastatin: 150 +/- 22%; P < 0.05) and in tendency endothelium-dependent relaxation (WHHL: 26 +/- 5 versus WHHL+ fluvastatin: 83 +/- 29%; (P = 0.07)). In parallel, fluvastatin restored nitrite plasma level in hyperlipoproteinemic animals (WHHL: 480 (13-3821) versus WHHL+ fluvastatin: 808 (467-1595) nmol; P < 0.05). Thus, chronic treatment with fluvastatin not only improves endothelial but also vascular smooth muscle function in hyperlipoproteinemia, which may contribute to the beneficial clinical effects of statins.     

Fluvastatin induces apoptosis in rat neonatal cardiac myocytes: a possible mechanism of statin-attenuated cardiac hypertrophy

Hydroxymethylglutaryl CoA (HMG-CoA) reductase inhibitors (statins) have been shown to reduce atherosclerotic cardiovascular mortality and morbidity. Recent evidence indicates that statins may also exert direct effects on vascular wall cells (including endothelial cells and smooth muscle cells) independently of their hypocholesterolemic properties. However, little is known about whether statins have direct effects on myocardium. The effect of lipophilic and hydrophilic statins (fluvastatin and pravastatin) on apoptosis and protein synthesis in rat neonatal cardiac myocytes was investigated. The presence of apoptosis was evaluated by morphologic criteria, electrophoresis of DNA fragments, 4",6"-diamidine-2"-phenylindole (DAPI) staining, and TUNEL assay. Protein synthesis was measured by H-leucine incorporation into the cells. Fluvastatin, but not pravastatin, induced apoptosis in cardiac myocytes in a time- and dose-dependent manner. The pro-apoptotic effect of fluvastatin was reversed in the presence of mevalonate or geranylgeranyl-pyrophosphate (GGPP), but not in the presence of squalene. The addition of protein prenylation inhibitor perillic acid and Rho-kinase inhibitor Y27632 significantly increased apoptosis. Fluvastatin decreased RhoA protein in the membrane fraction, whereas there were no significant changes of the RhoA protein in the cytosol fraction. Interleukin-1beta-stimulated H-leucine incorporation was completely inhibited by fluvastatin, but not by pravastatin. The findings suggest that fluvastatin induces apoptosis in cardiac myocytes via protein prenylation and the subsequent inhibition of Rho, and may play a role in the pathogenesis of cardiac hypertrophy and remodeling.     

Pravastatin inhibits arrhythmias induced by coronary artery ischemia in anesthetized rats

We have reported that chronically administered pravastatin prevented coronary artery reperfusion-induced lethal ventricular fibrillation (VF) in anesthetized rats without lowering the serum cholesterol level. The present study was undertaken to evaluate whether pravastatin prevents ischemia-induced lethal VF, simultaneously examining myeloperoxidase (MPO) activity in ischemic myocardial tissues. Anesthetized rats were subjected to 30-min ischemia and 60-min reperfusion after chronic administration of pravastatin (0.02, 0.2, and 2 mg/kg), fluvastatin (2 and 4 mg/kg), or vehicle for 22 days, orally, once daily. ECG and blood pressure were continually recorded, and MPO was measured by a spectrophotometer. Pravastatin and fluvastatin significantly (P<0.05) decreased MPO activities, but only pravastatin decreased the incidence of ischemia-induced lethal VF. Both statins had no significant effects on body weight, blood pressure, heart rate, and QT interval as we reported earlier. Our results prove further that pravastatin has benefits to decrease cardiovascular mortality beyond its cholesterol-lowering effect. Pravastatin is more potent than fluvastatin in prevention of arrhythmias. A decrease in the neutrophil infiltration may be partly involved in the inhibitory effect of pravastatin on the ischemia-induced VF.     

Pravastatin prevents arrhythmias induced by coronary artery ischemia/reperfusion in anesthetized normocholesterolemic rats

HMG-CoA reductase inhibitors (statins) have been shown to decrease cardiovascular mortality. Since ventricular tachyarrhythmias are closely related to cardiovascular mortality, we tested effects of the hydrophilic statin pravastatin and the lipophilic statin fluvastatin in a rat arrhythmia model of ischemia/reperfusion and simultaneously measured serum total cholesterol level. Anesthetized rats were subjected to 5-min ischemia and 10-min reperfusion after chronic administration of oral pravastatin (0.02, 0.2, or 2 mg/kg), fluvastatin (0.2, 2, or 4 mg/kg), or vehicle for 22 days, once daily. The acute effect of pravastatin (0.2 or 2 mg/kg, once orally) was also observed. Chronically administrated pravastatin significantly reduced the incidence of ischemia-induced ventricular tachycardia (VT) from 70% (control) to 9% at 2 mg/kg, and it reduced the incidence of reperfusion-induced lethal ventricular fibrillation (VF) from 90% (control) to 20% at 0.2 mg/kg. Acute pravastatin and chronically administrated fluvastatin had no significant effect on these arrhythmias. There were no significant changes in blood pressure, heart rate, QT interval, and serum cholesterol among pravastatin-, fluvastatin-, and vehicle-treated groups. Hydrophilic pravastatin prevented reperfusion-induced lethal VF in anesthetized rats by chronic administration independent of its cholesterol lowering effect. This may be a new beneficial role of pravastatin in decreasing cardiovascular mortality.     

Pravastatin attenuates left ventricular remodeling and diastolic dysfunction in angiotensin II-induced hypertensive mice

BACKGROUND: A substantial proportion of patients with heart failure have a normal ejection fraction and diastolic dysfunction. However, there are few data available to guide the therapy of these patients. The effects of statins on cardiac remodeling are well documented in animal models and it is reported that statin therapy revealed a survival benefit in patients with diastolic heart failure (DHF). However, the exact mechanisms of statins possibly explaining the decreased cardiovascular morbidity and mortality in patients with DHF have not been elucidated. METHODS: We used 8-week-old male C57BL/6J mice, in which angiotensin II was subcutaneously infused for 4 weeks to mimic cardiac remodeling and fibrosis. They were treated with either normal saline or pravastatin in daily doses, which did not lower the serum cholesterol levels and blood pressure. RESULTS: Pravastatin improved diastolic dysfunction in angiotensin II-induced hypertensive mice, which was associated with the amelioration of left ventricular hypertrophy and remodeling. However, statin treatment showed no effect on the increased systolic blood pressure or cholesterol levels by angiotensin II infusion. The cardioprotective effects of pravastatin were closely associated with the downregulation of collagen I, transforming growth factor-beta, matrix metalloproteinases-2 and -3, atrial natriuretic factor, interleukin-6, tumor necrosis factor-alpha, ROCK1 gene expression, and the upregulation of endothelial nitric oxide synthase gene expression. CONCLUSIONS: The beneficial effects of pravastatin on DHF and structural remodeling are through cholesterol- independent mechanism of statins or "pleiotropic" effects of statins involving improving or restoring endothelial function and decreasing vascular inflammation. These findings suggest the potential involvement of ROCK1. Thus, treatment with pravastatin might be beneficial in patients with DHF.     

Treatment strategies for hot flushes

Background: Vasomotor symptoms are the most common complaints for which menopausal women seek medical care. Eighty per cent of all menopausal women will have hot flushes and night sweats, and of these 9% will have severe symptoms impacting their quality of life. Ideally, treatment should target the group most severely afflicted, and options for treatment should be tailored to each woman, since, for most women, vasomotor symptoms spontaneously resolve in 3 – 5 years. Recommendation at this time is for the shortest duration of therapy, which means that episodic review of therapy is indicated. Objective: To review the latest literature investigating therapies for vasomotor symptoms and to discuss their effectiveness with emphasis on placebo-controlled, randomized clinical trials. Methods: A literature search in PubMed for ‘vasomotor symptoms’, ‘menopause symptoms’, ‘hot flushes’, ‘hot flashes’ and ‘night sweats’ from 2003 to the present was performed. Conclusions: Estrogen remains the gold standard for treating vasomotor symptoms. As investigations into the physiology of hot flushes continue, centrally active drugs (selective serotonin or norepinephrine-serotonin reuptake inhibitors and gabapentin) have increased in use. The benefit from dietary herbal supplements is still inconclusive; however, recent studies have shown some mild response to soy and black cohosh.     

Comparison of the efficacies of five different statins on inhibition of human saphenous vein smooth muscle cell proliferation and invasion

Statins (HMG-CoA reductase inhibitors) exhibit beneficial effects on the vasculature independently of their cholesterol-lowering properties. These pleiotropic effects underlie the ability of statins to reduce intimal hyperplasia in saphenous vein (SV) bypass grafts by attenuating smooth muscle cell (SMC) invasion and proliferation. Although all statins can effectively lower cholesterol, the pleiotropic effects of individual statins may well differ. We therefore compared the concentration-dependent effects of 4 lipophilic statins (simvastatin, atorvastatin, fluvastatin, and lovastatin) and 1 hydrophilic statin (pravastatin) on the proliferation and invasion of SMC cultured from SV of 9 different patients undergoing coronary artery bypass grafting (CABG). The lipophilic statins inhibited SV-SMC proliferation over a 4-day period with an order of potency of fluvastatin > atorvastatin > simvastatin > lovastatin (IC50 range = 0.07 to 1.77 microM). Similarly, these statins also inhibited SV-SMC invasion through an artificial basement membrane barrier (fluvastatin > atorvastatin > simvastatin > lovastatin; IC50 range = 0.92 to 26.9 microM). In contrast, the hydrophilic pravastatin had no significant effect on SV-SMC proliferation at concentrations up to 10 microM, nor did it attenuate SV-SMC invasion (up to 30 microM). Our data provide strong evidence that individual statins possess differential pleiotropic effects on SV-SMC function. This may be of clinical relevance in the selection of individual statins for the treatment of CABG patients.     

HMG CoA reductase inhibitors affect the fibrinolytic system of human vascular cells in vitro: a comparative study using different statins

1. The results of several clinical studies investigating the effect of statin therapy on the fibrinolytic system in vivo are inconclusive. We compared the effect of six different statins (atorvastatin, cerivastatin, fluvastatin, lovastatin, pravastatin, simvastatin) on components of the fibrinolytic system expressed by human vascular endothelial cells and smooth muscle cells and by the human hepatoma cell line HepG2. 2. All statins used except pravastatin significantly decreased PAI-1 production in human endothelial and smooth muscle cells. This effect was also seen in the presence of IL-1 alpha and TNF-alpha. All statins except pravastatin increased t-PA production in human smooth muscle cells. On a molar basis cerivastatin was the most effective HMG CoA reductase inhibitor used. Only simvastatin and lovastatin increased t-PA production in endothelial cells. The effects on the fibrinolytic system were reversed by mevalonate. Statins decreased mRNA levels for PAI-1 in endothelial and smooth muscle cells and increased mRNA levels for t-PA in smooth muscle cells. Statins did not affect PAI-1 expression in HepG2 cells. Cell viability was not influenced by statins in endothelial cells and HepG2 cells whereas in smooth muscle cells a cytotoxic effect was seen at high concentrations. 3. If the effects on the fibrinolytic system of vascular cells in vitro shown in this study are also operative in vivo one could speculate that by increasing t-PA and decreasing PAI-1 at sites of vascular lesions statins might reduce fibrin formation and thrombus development. Such an effect might contribute to the clinically proven benefits of statin therapy.     

Effects of extracts from Cimicifuga racemosa on gonadotropin release in menopausal women and ovariectomized rats.

Remifemin is an ethanolic extract of the rhizome of Cimicifuga racemosa (C.r.) and is used to relieve climacteric hot flushes. In the present study the effects of this preparation on LH and FSH secretion of menopausal women were investigated. After an 8 weeks treatment, LH but not FSH levels were significantly reduced in patients receiving the Cimicifuga extract. To further characterize the endocrinologically active principles of this plant extract, a lipophilic extract of C.r. was prepared and subjected to Sephadex chromatography. Fractions obtained were tested for their ability to reduce LH secretion in ovariectomized (ovx) rats and to compete in vitro with 17 beta-estradiol for estrogen receptor binding sites. Three types of endocrinologically active compounds were obtained: (1) Constituents which were not ligands for the estrogen receptor but suppress LH release after chronic treatment, (2) constituents binding to the estrogen receptor and also suppressing LH release, and (3) compounds which are ligands for the estrogen receptor but without an effect of LH release. It is concluded that the LH suppressive effect of C.r. extracts observed in menopausal women and ovx rats is caused by at least three different synergistically acting compounds.