Voluntary alcohol consumption and plasma beta-endorphin levels in alcohol preferring rats chronically treated with lamotrigine.

Several recent studies have indicated that lamotrigine, similarly to other antiepileptic drugs, may be useful in the therapy of alcohol dependence. The rationale for using lamotrigine in the treatment of alcohol addiction is based on its multiple mechanisms of action which include inhibition of voltage-sensitive sodium channels, modulation voltage-gated calcium currents and transient potassium outward current. However, the known mechanism of lamotrigine does not fully explain its efficacy in alcohol addiction therapy. For this reason we have decided to examine the effect of lamotrigine on the opioid system. Our previous studies showed that topiramate and levetiracetam (antiepileptic drugs) as well as the most effective drugs in alcohol addiction therapy i.e. naltrexone and acamprosate, when given repeatedly, all increased plasma beta endorphin (an endogenous opioid peptide) level, despite operating through different pharmacological mechanisms. It is known that low beta-endorphin level is often associated with alcohol addiction and also that alcohol consumption elevates the level of this peptide. This study aims to assess the effect of repeated treatment with lamotrigine on voluntary alcohol intake and beta-endorphin plasma level in alcohol preferring rats (Warsaw high preferring (WHP) rats). We observed a decrease in alcohol consumption in rats treated with lamotrigine. However we didn't observe significant changes in beta-endorphin level during withdrawal of alcohol, which may indicate that the drug does not affect the opioid system. We suppose that lamotrigine may be useful in alcohol dependence therapy and presents a potential area for further study.

The effects of celiprolol on serum concentrations of proinflammatory cytokines in hypertensive (SHR) and normotensive (WKY) rats.

BACKGROUND: A growing body of evidence suggests that some cardiovascular drugs could modulate the level of proinflammatory cytokines. Therefore, the aim of the present study was to investigate whether celiprolol, a third generation ß-adrenoceptor blocker, affects lipopolysaccharide (LPS)-induced serum concentrations of TNF-α, IL-1ß, IL-6 in normotensive (WKY) and spontaneously hypertensive (SHR) rats. METHODS: Celiprolol (150 mgkg(-1)) or vehicle was administered by gavage once daily for 21 days. Arterial blood pressure was measured in conscious rats, using the tail-cuff method. Serum concentrations of proinflammatory cytokines were measured with enzyme-linked immunosorbent assay kits. Additionally, plasma concentrations of total cholesterol, HDL-cholesterol and triglycerides were evaluated. RESULTS: In normotensive WKY rats celiprolol did not affect heart rate, blood pressure, or the serum concentrations of triglycerides, total cholesterol or HDL-cholesterol. In hypertensive animals the drug decreased lipid parameters, increased diastolic and mean blood pressure after the first week of administration, and produced a small but significant decrease in heart rate after the first two weeks of the treatment. In both groups of animals, celiprolol decreased LPS-stimulated serum concentration of IL-6 but did not affect levels of TNF-α and IL-1ß. CONCLUSIONS: It is suggested that the IL-6-modulating properties of celiprolol could provide additional value to the therapeutic effectiveness of the drug in the treatment of hypertension.

Effect of repeated treatment with topiramate on voluntary alcohol intake and beta-endorphin plasma level in Warsaw alcohol high-preferring rats.

RATIONALE: Pharmacological treatment currently used for alcohol dependence is not sufficient for the all patients, and there is a crucial need to find more effective treatments. Recent studies indicate that topiramate is likely the most promising new medication for alcohol dependence. The rationale for topiramate as treatment for alcohol addiction is based on its multifaceted neurochemical activity that targets multiple neural pathways. OBJECTIVES: This study aims to assess the effect of repeated treatment with topiramate on voluntary alcohol intake and beta-endorphin plasma level in rats selectively bred for high alcohol preference. METHODS: Initially, Warsaw high preferring rats (N = 50) were given a 24-h/day free choice between a 10 % (v/v) alcohol solution and water for three consecutive weeks. Subsequently, rats were administered with topiramate (40 or 80 mg/kg b.w.) or vehicle for 14 days and ethanol intake was measured daily. Subsequently, we examined the effects of topiramate on plasma beta-endorphin levels, while alcohol was available and when it was not available for an extended period time. RESULTS: We observed significantly increase in the levels of beta-endorphin in rats with free access to alcohol both in a topiramate- or vehicle-treated group. However, in topiramate-treated group, a voluntary consumption of alcohol diminished in comparison with the vehicle-treated rats. CONCLUSION: The results from this study indicated that topiramate reduces voluntary alcohol intake and support our previous findings that the increase of beta-endorphin level is responsible at least partly for the effectiveness of drugs in treating the alcohol addiction.

Voluntary alcohol consumption and plasma beta-endorphin levels in alcohol preferring rats chronically treated with levetiracetam: a preliminary study.

Many recent researches have confirmed the effectiveness of antiepileptic drugs in preventing alcohol dependency, whereas our previous study showed that repeated treatment with topiramate, a new antiepileptic drug, was effective in increasing the plasma levels of beta-endorphin (an endogenous opioid peptide) in rats. It is well documented that in humans a genetic deficit of beta-endorphin is often associated with alcohol addiction as alcohol consumption elevates the level of this peptide. The aim of the present study is multifaceted: to investigate the effect of repeated treatment of levetiracetam (50 or 100mg/kg b.w., twice daily) on voluntary alcohol intake in alcohol preferring rats (Warsaw High Preferring; WHP) and to assess changes in plasma beta-endorphin levels while alcohol is available and when it is not available for an extended period of time. We observed a noticeable increase in the levels of beta-endorphin in rats with free access to alcohol whether in a prolonged levetiracetam-treated or vehicle-treated group. However, in the levetiracetam group, a voluntary intake of alcohol diminished in comparison with both the pretreatment period and in comparison with the vehicle-treated rats. A similar increase in the plasma beta-endorphin levels was observed in levetiracetam-treated rats that did not have access to ethanol. This finding lets us to believe that levetiracetam may be a promising medication in treatment of alcohol dependency as its application leads to the increase in the beta-endorphin concentration and ultimately results in reducing deficiency of this peptide.

Does nebivolol influence serum concentrations of proinflammatory cytokines in hypertensive (SHR) and normotensive (WKY) rats?

A growing body of evidence suggests that some drugs used in cardiovascular diseases may modulate the level of proinflammatory cytokines. In the present study we examined whether nebivolol, a third generation beta-adrenergic blocker, influences lipopolysaccharide (LPS)-induced serum concentrations of TNF-alpha, IL-1beta, and IL-6 in normotensive (WKY) and spontaneously hypertensive rats (SHR). Nebivolol (5 mg/kg and 10 mg/kg) or vehicle were administered by gavage once a day for 21 days. The drug (5 mg/kg and 10 mg/kg) did not modify LPS-stimulated serum concentrations of TNF-alpha, IL-1beta and IL-6 in normotensive or hypertensive rats and did not affect the total cholesterol and HDL cholesterol level. Nebivolol, at the dose of 10 mg/kg, significantly increased the triglyceride concentration in SHR only. The results were accompanied by a statistically significant decrease in systolic, diastolic and mean blood pressure after 21 days of both of the drug doses. In hypertensive and normotensive rats, nebivolol had a hypotensive activity and neutral effect on lipid profile. In our in vivo model, the immunomodulating effect of the drug was not significant and probably did not depend on hemodynamic action.

Synthesis, pharmacological activity and nitric oxide generation by nitrate derivatives of theophylline.

Nitrates of theophylline derivatives - potential nitric oxide (NO) donors - were synthesized by esterification of 7-hydroxyalkyl theophylline derivatives with fuming nitric acid. The nitrates obtained were tested in-vitro in reactions with sulfydryl compounds at appropriately adjusted pH and temperature. Under the applied conditions, the synthesized compounds underwent decomposition to release NO, quantified using a polarographic method using a selective isolated (ISO-NO) sensor. The effects of dyphylline and proxyphylline and their new synthesized nitrates on arterial blood pressure (BP) were measured in spontaneously hypertensive (SH) rats. BP was measured in conscious SH rats using the tail-cuff method. Both short- and long-term administration of the xanthines tested significantly decreased systolic, diastolic and mean BP. The hypotensive effect of a single dose of nitrate dyphylline on mean BP was greater than that of the parent compound (P = 0.000012; P=0.000472 at 30 and 60 min post-dose, respectively), whereas proxyphylline and its nitrate derivative had similar activity. In rats treated with the tested compounds for 9 days twice daily, the decrease in BP persisted for at least 16 h after the last dose. Proxyphylline produced the most marked decrease in diastolic and mean BP. Among the xanthines examined, proxyphylline nitrate had the strongest hypotensive effect when administered in a single dose to animals pretreated with the same compound for 9 days. These results indicate that insertion of a nitrate group weakly modifies the hypotensive action of the studied xanthines in SH rats.

Voluntary alcohol consumption and plasma beta-endorphin levels in alcohol-preferring rats chronically treated with naltrexone.

It is well known that alcohol consumption leads to an increase in the levels of beta-endorphin (an endogenous opioid), which can contribute to the reinforcing effect of alcohol. Our previous studies have shown that repeated treatment with naltrexone, a nonselective opioid antagonist, results in increased plasma beta-endorphin levels. Ample studies in animals and humans have shown that naltrexone diminishes ethanol consumption. The aim of the present study in alcohol-preferring rats (Warsaw High Preferring; WHP) was to investigate the effect of 10 days of naltrexone treatment (2 mg/kg i.p.) on voluntary alcohol intake and on changes in plasma beta-endorphin levels while alcohol was available and 10 days after imposed abstinence. It was observed that voluntary alcohol intake induces an increase in plasma beta-endorphin levels in WHP rats. After a 10-day period of alcohol withdrawal, the levels of this peptide were significantly reduced compared with the levels in rats with free access to ethanol and in control alcohol-naïve rats. In chronic naltrexone-treated rats with free access to alcohol, an increase in the levels of this peptide was also observed; however, voluntary alcohol intake was diminished. A similar increase in plasma beta-endorphin levels was observed in naltrexone-treated rats that did not have access to ethanol. As the endogenous opioid system has an important role in the development of a craving for alcohol, it is likely that chronic naltrexone treatment may have a beneficial effect leading to a compensatory increase in the beta-endorphin concentration and ameliorating its deficiency during ethanol withdrawal. Restoring the alcohol-induced deficiency of beta-endorphin may be an important factor in the prevention of craving and maintenance of abstinence. This finding supports the proposition that the endogenous opioid system plays an important role in developing a craving for alcohol.

Effect of chronic acamprosate treatment on voluntary alcohol intake and beta-endorphin plasma levels in rats selectively bred for high alcohol preference.

Our previous studies have shown that repeated acamprosate administration to ethanol-naive Warsaw high preferring (WHP) rats resulted in increased plasma beta-endorphin levels and at least partially prevents increases in levels of this peptide after a single administration of ethanol compared with untreated control rats. The objective of the present study, which included 45 WHP rats, was to continue the past research and investigate the effect of 10-day acamprosate treatment (200 mg/kg p.o.) on alcohol intake using a free-choice procedure and on changes in plasma beta-endorphin levels while alcohol is available, and 10 days after alcohol withdrawal. Voluntary alcohol consumption increases plasma levels of beta-endorphin from 440+/-25 pg/ml to 711+/-57 pg/ml (p=0.0002). After a 10-day of alcohol withdrawal, the levels of this peptide were significantly reduced compared with levels in rats with free access to ethanol (711+/-57 pg/ml vs. 294+/-38 pg/ml, p=0.000001) and in control naive rats (440+/-25pg/ml vs. 294+/-38pg/ml, p=0.044). Chronic treatment with acamprosate increased plasma beta-endorphin levels both in WHP rats with free access to ethanol (440+/-25 pg/ml vs. 616+/-49 pg/ml, p=0.008) and in rats after ethanol withdrawal (440+/-25 pg/ml vs. 620+/-56 pg/ml, p=0.007). In the group with free access to ethanol, there was a significant reduction in mean ethanol intake, from 6.75+/-0.20 g/kg body weight/day to 4.68+/-0.25 g/kg/day. Our results indicate that chronic acamprosate treatment may have beneficial effects, as it increases the beta-endorphin concentration thereby compensating for beta-endorphin deficiency during ethanol withdrawal. As the endogenous opioid system has an important role in the development of craving for alcohol, restoring the alcohol-induced deficits in beta-endorphin levels may be an important factor to prevent craving and maintaining abstinence. We suppose that the anti-craving mechanism of acamprosate that has been reported to abolish excessive glutamate release during alcohol withdrawal may be accompanied by compensation for the beta-endorphin deficiency.

Influence of enalapril, quinapril and losartan on lipopolysaccharide (LPS)-induced serum concentrations of TNF-alpha, IL-1 beta, IL-6 in spontaneously hypertensive rats (SHR).

Immunopharmacological studies of drugs used in cardiovascular diseases provide new data concerning their modulating effect on the levels of proinflammatory cytokines, chemokines and adhesion molecules. Therefore, we have made an attempt to find out whether enalapril, quinapril and losartan (drugs used in the treatment of arterial hypertension) are able to modulate lipopolysaccharide (LPS)-induced proinflammatory cytokine serum concentrations (tumor necrosis factor alpha - TNF-alpha, interleukin-1 beta _ IL-1 beta, interleukin-6 - IL-6) in spontaneously hypertensive rats (SHR). The animals were divided into four groups as follows: SHR + M (control rats receiving 1% solution of methylcellulose), SHR + E (rats receiving enalapril - 10 mg/kg), SHR + Q (rats receiving quinapril - 10 mg/kg) and SHR + L(rats receiving losartan - 20 mg/kg). 1% solution of methylcellulose and hypotensive drugs were administered by a gavage for 21 days. Arterial blood pressure was measured in conscious rats, using the tail-cuff method. Twenty four hours after the last administration of enalapril, quinapril, losartan or 1% solution of methylcellulose, the rats received a single dose of LPS (ip; 0.1 mg/kg). After 2 h, the rats were anesthetized with ether and the blood samples were collected by heart puncture. Serum TNF-alpha, IL-1 beta and IL-6 concentrations were measured with enzyme-linked immunosorbent assay kits. Additionally, total cholesterol and high density lipoprotein (HDL) cholesterol were evaluated. Enalapril, quinapril and losartan significantly decreased LPS-stimulated TNF-alpha and IL-1 beta level after 21 days. Three-week administration of quinapril lowered IL-6 serum concentration after LPS stimulation. Enalapril and losartan did not affect the IL-6 level. The results were accompanied by a statistically significant decrease in systolic, diastolic and mean blood pressure. Hypotensive drugs also showed no effect on lipid level. The latest data indicate additional properties of hypotensive drugs. However, further studies are necessary to elucidate precisely the role of proinflammatory cytokines in arterial hypertension.

Effect of repeated treatment with topiramate on the beta-endorphin plasma level in rats selectively bred for high and low alcohol preference.

Recent research indicates that topiramate has a role in the treatment of alcohol dependence. Topiramate has multiple mechanisms of action including enhancement of GABA-ergic inhibitory transmission and blocking excitatory glutamate neurotransmission, and modulating voltage-gated sodium and calcium ion channels and inhibiting carbonic anhydrase. In this study, we examined the effect of topiramate on endogenous opioid systems, which have an important role in the development of alcohol dependence. We investigated the beta-endorphin plasma level of animals with high- and low-risks of alcohol dependency after repeated treatment with topiramate. We used the Warsaw High Preferring (WHP) and Warsaw Low Preferring (WLP) rats, and treated them with topiramate at a dose of 80 mg/kg p.o. for 14 days. In WHP rats treatment with topiramate led to an increase in beta-endorphin plasma levels, which persisted at the same level even after a single injection of alcohol. The level of this peptide with topiramate was lower than in alcohol-injected WHP rats who did not receive topiramate. Beta-endorphin levels in WHP rats after topiramate or topiramate and ethanol treatment were similar to the basal level of this peptide in WLP rats. In WLP rats, topiramate did not prevent the ethanol-induced increase in beta-endorphin plasma level. We propose that administration of topiramate may have different effects on the opioid system involved in dependence according to genetic susceptibilities to alcoholism.

Influence of amlodipine and atenolol on lipopolysaccharide (LPS)-induced serum concentrations of TNF-alpha, IL-1, IL-6 in spontaneously hypertensive rats (SHR).

An increasing body of evidence suggests that cytokines may play a role in the pathogenesis of cardiovascular diseases. Immunopharmacological studies provide new information on immunomodulating activity of some drugs, including their effect on the level of pro-inflammatory cytokines. The aim of the present study was to find out whether amlodipine and atenolol, drugs applied in the treatment of arterial hypertension, can modulate lipopolysaccharide (LPS)-induced pro-inflammatory cytokine level (TNF-alpha, IL-1, IL-6) in spontaneously hypertensive rats (SHR). The experiments were performed on 4 groups of animals as follows: WKY + MET(control Wistar-Kyoto normotensive rats), SHR + MET(control hypertensive rats), SHR + AML(hypertensive rats receiving amlodipine), SHR + AT (hypertensive rats receiving atenolol). Control rats received 1% solution of methylcellulose (1 ml/kg) by a gavage. Amlodipine and atenolol were administered by a gavage at doses of 15 mg/kg and 25 mg/kg, respectively. Arterial blood pressure was measured in conscious rats, using the tail-cuff method. Serum tumor necrosis factor alpha (TNF)-alpha, interleukin (IL)-1 and IL-6 concentrations were measured with enzyme-linked immunosorbent assay kits. Additionally, lipid levels were evaluated. The present data provide the evidence that amlodipine and atenolol act as immunomodulators of pro-inflammatory cytokines in SHR. Amlodipine decreased TNF-alpha, increased IL-6 and did not affect IL-1 level. Atenolol did not influence TNF-alpha and IL-1, but raised IL-6 in SHR. Additionally, amlodipine decreased total cholesterol level without changing HDL cholesterol level whereas atenolol did not influence lipid levels. The identification of additional immunomodulating properties of hypotensive drugs may be important for better understanding of their mechanisms of action.

Effect of acute administration of ethanol on beta-endorphin plasma level in ethanol preferring and non-preferring rats chronically treated with naltrexone.

An ample support can be found in professional literature for the hypothesis that the endogenous opioid system plays an important role in developing a craving for alcohol. It is well established that people with a genetic deficit of beta-endorphin are particularly susceptible to alcoholism. In our study, we looked into the beta-endorphin plasma level of animals with high- and low-risk of alcohol dependency after repeated treatment with naltrexone, the opioid antagonist known to be effective in the treatment of alcoholism. We used the Warsaw High Preferring (WHP) and Warsaw Low Preferring (WLP) rats and treated them for 10 days with naltrexone in a dose of 2 mg/kg i.p. One hour before blood collection the rats were injected with a single dose of ethanol. A prolonged naltrexone treatment or a single application of ethanol resulted in the increase of the beta-endorphin plasma level. In the WLP rats repeated naltrexone treatment prevents the ethanol-induced increase in beta-endorphin plasma level. In the WHP rats the level of this peptide was similar to it while they were undergoing the naltrexone treatment or had received a single alcohol injection. This finding supports the proposition that the endogenous opioid system plays an important role in developing a craving for alcohol. It is likely that effectiveness of naltrexone in reducing craving for alcohol results from the attenuation of the rewarding properties of ethanol and restoring the beta-endorphin deficit in reward system.

[Drugs used in cardiovascular diseases and cytokines]. / Leki stosowane w chorobach ukladu krazenia a cytokiny.

Immunopharmacological studies show that medicines used in cardiovascular diseases (atherosclerosis, ischaemic heart disease, heart failure) can exert immunomodulatory effects on proinflammatory cytokines. In the paper the influence of statins, fibrates, angiotensin converting enzyme inhibitors (ACEI), beta-blockers, calcium channel blockers and phosphodiesterase inhibitors on the activity of cytokines was introduced.

Study on organic nitrates, part VIII. Pharmacological activity and nitric oxide generation capacity of nitrate derivatives of piperazine.

Organic nitrates, derivatives of piperazine, incubated with L-cysteine hydrochloride in phosphate buffer at appropriately high pH and temperature underwent decomposition, releasing nitric oxide (NO). NO generated in this reaction was quantitated by polarographic method using a selective ISO NO sensor. Spontaneously hypertensive rats were used in the tests of hypotensive activity of both investigated organic nitrates and their hydroxyl analogues. The experiments with both groups of compounds were performed under identical conditions. The results of the study demonstrated that the ability of individual compounds to release NO influenced in a different manner their pharmacological activity. Only the compound which released the largest quantity of NO during in vitro tests exhibited in vivo the most prolonged hypotensive effect and significant decrease in all arterial blood pressure parameters.

Interaction of mianserin and some hypotensive drugs in Wistar rats.

Mianserin is thought to exert little effect on the cardiovascular system. In fact its safety in comparison with tricyclic drugs is high. Various experiments gave varying results as for the influence of the drug on arterial blood pressure in people and animals. Therefore, a study was undertaken in Wistar rats to evaluate interactions of mianserin administered intraperitoneally as a single dose, and for 21 days with 3 hypotensive drugs showing different mechanism of action (propranolol, enalapril, prazosine). The systolic, diastolic and mean blood pressure was measured with a LETICA apparatus. The results of the study revealed that administration of mianserin in normotensive rats leads to a short-term decrease in blood pressure and significantly enhanced the hypotensive effect of prazosine. Repeated doses of mianserin lead to a temporary increase in blood pressure after 2 weeks of administration. Single and repeated administration of mianserin did not change the hypotensive effect of propranolol and enalapril. Three-week therapy with mianserin significantly enhanced the hypotensive effect of prazosine.

Influence of mianserin on the activity of some hypotensive drugs in spontaneously hypertensive rats.

Mianserin might be an alternative drug in patients with depression accompanied by hypertension because of its effectiveness and lack of side effects in the circulatory system. However, a few studies reported in literature show influence of the drug on blood pressure. We investigate interactions between mianserin and commonly used hypotensive drugs (propranolol, enalapril and prazosin) in spontaneously hypertensive rats (SHR). The experiments were performed in two experimental designs: a single administration of both mianserin and a hypotensive drug, and repeated administration of mianserin with a single administration of a hypotensive drug. Arterial blood pressure was measured by bloodless method with manometer made by LETICA. A single administration of mianserin caused a statistically significant decrease in systolic, diastolic and mean blood pressure in the 60th minute of observation and intensified hypotensive effect of prazosin. However, long-term administration of mianserin in SHR rats had no significant influence on arterial blood pressure. Chronic and single administration of mianserin with propranolol or enalapril did not influence the circulatory system. A long-term administration of mianserin intensified the hypotensive effect of prazosin. This interaction might suggest possibility of dangerous complications in the treatment of humans with this drug combination.