Treatment with a novel oleic-acid-dihydroxyamphetamine conjugation ameliorates non-alcoholic fatty liver disease in obese Zucker rats.

Fatty liver disease is one of the main hepatic complications associated with obesity. To date, there are no effective treatments for this pathology apart from the use of classical fibrates. In this study, we have characterized the in vivo effects of a novel conjugation of oleic acid with an amphetamine derivative (OLHHA) in an animal model of genetic obesity. Lean and obese Zucker rats received a daily intraperitoneal administration of OLHHA (5 mg kg(-1)) for 15 days. Plasma and liver samples were collected for the biochemical and molecular biological analyses, including both immunohistochemical and histological studies. The expression of key enzymes and proteins that are involved in lipid metabolism and energy homeostasis was evaluated in the liver samples. The potential of OLHHA to produce adverse drug reactions or toxicity was also evaluated through the monitoring of interactions with hERG channel and liver cytochrome. We found that OLHHA is a drug with a safe pharmacological profile. Treatment for 15 days with OLHHA reduced the liver fat content and plasma triglyceride levels, and this was accompanied by a general improvement in the profile of plasma parameters related to liver damage in the obese rats. A decrease in fat accumulation in the liver was confirmed using histological staining. Additionally, OLHHA was observed to exert anti-apoptotic effects. This hepatoprotective activity in obese rats was associated with an increase in the mRNA and protein expression of the cannabinoid type 1 receptor and a decrease in the expression of the lipogenic enzymes FAS and HMGCR primarily. However, changes in the mRNA expression of certain proteins were not associated with changes in the protein expression (i.e. L-FABP and INSIG2). The present results demonstrate that OLHHA is a potential anti-steatotic drug that ameliorates the obesity-associated fatty liver and suggest the potential use of this new drug for the treatment of non-alcoholic fatty liver disease.

Pro-oxidant effects of Ecstasy and its metabolites in mouse brain synaptosomes.

BACKGROUND AND PURPOSE: 3,4-Methylenedioxymethamphetamine (MDMA or 'Ecstasy') is a worldwide major drug of abuse known to elicit neurotoxic effects. The mechanisms underlying the neurotoxic effects of MDMA are not clear at present, but the metabolism of dopamine and 5-HT by monoamine oxidase (MAO), as well as the hepatic biotransformation of MDMA into pro-oxidant reactive metabolites is thought to contribute to its adverse effects. EXPERIMENTAL APPROACH: Using mouse brain synaptosomes, we evaluated the pro-oxidant effects of MDMA and its metabolites, α-methyldopamine (α-MeDA), N-methyl-α-methyldopamine (N-Me-α-MeDA) and 5-(glutathion-S-yl)-α-methyldopamine [5-(GSH)-α-MeDA], as well as those of 5-HT, dopamine, l-DOPA and 3,4-dihydroxyphenylacetic acid (DOPAC). KEY RESULTS: 5-HT, dopamine, l-DOPA, DOPAC and MDMA metabolites α-MeDA, N-Me-α-MeDA and 5-(GSH)-α-MeDA, concentration- and time-dependently increased H(2) O(2 ) production, which was significantly reduced by the antioxidants N-acetyl-l-cysteine (NAC), ascorbic acid and melatonin. From experiments with MAO inhibitors, it was observed that H(2) O(2) generation induced by 5-HT was totally dependent on MAO-related metabolism, while for dopamine, it was a minor pathway. The MDMA metabolites, dopamine, l-DOPA and DOPAC concentration-dependently increased quinoproteins formation and, like 5-HT, altered the synaptosomal glutathione status. Finally, none of the compounds modified the number of polarized mitochondria in the synaptosomal preparations, and the compounds' pro-oxidant effects were unaffected by prior mitochondrial depolarization, excluding a significant role for mitochondrial-dependent mechanisms of toxicity in this experimental model. CONCLUSIONS AND IMPLICATIONS: MDMA metabolites along with high levels of monoamine neurotransmitters can be major effectors of neurotoxicity induced by Ecstasy.

The mydriatic effect of intracameral epinine hydrochloride.

PURPOSE: To compare the mydriatic effect and the short-term corneal endothelial safety of intracamerally injected N-methyl-3,4-dihydroxyphenylamine (epinine) to phenylephrine in a porcine eye model. METHODS: One hundred twelve eyes from newly slaughtered pigs were used in this study. After pretreatment with 20 mg intracameral acetylcholine to give miosis, 0.15 mL epinine or phenylephrine 0.3%, 1.5%, or 3.0% was given as an intracameral injection. The pupils were filmed during 90 seconds with a video camera connected to an operation microscope, and the mean pupil diameters were measured from the video recordings. In 37 additional eyes, 0.15 mL vehicle, 1.5% epinine, or 1.5% phenylephrine was injected intracamerally, and the eyes were kept on ice overnight. Corneal endothelial morphology was assessed before and after the treatment. Ten eyes were given no injection and served as controls. RESULTS; Epinine had a significantly larger mydriatic effect than phenylephrine at equal concentrations. Endothelial cell loss was equal with both substances and did not exceed that of the vehicle. CONCLUSIONS: Epinine was a more potent mydriatic than phenylephrine in this porcine eye model. The porcine eye model appears suitable as a first efficacy screening of substances for intraocular use. Epinine is a promising candidate substance for intraoperative (e.g., cataract surgery) intracameral use in humans.

Effect of methyl derivatives of dopamine on tumor necrosis factor alpha and lipid peroxidation.

We recently demonstrated that melatonin, N-acetylserotonin (NAS), and N-acetyldopamine (NAD) attenuate the synthesis of lipopolysaccharide (LPS)-stimulated tumor necrosis factor-alpha (TNF-alpha) and the generation of oxidant radicals. In this study, we examined whether acetyl and methyl derivatives of dopamine modulate LPS-stimulated TNF-alpha synthesis and LPS- and iron-induced lipid peroxidation. Differentiated THP-1-derived human monocytes were coincubated with Escherichia coli and rising concentrations of NAS, NAD, N-methyldopamine (NMD), or 4-O-methyldopamine (4-O-MD). After 24 h, TNF-alpha was measured in cell supernatants. In addition, lipid peroxidation was induced by adding FeCl(2) solution to mouse brain tissue homogenates in the presence of rising concentrations of NAS, NAD, NMD, or 4-O-MD. Incubating THP-1-derived monocytes with rising concentrations of NAS, NAD, NMD, or 4-O-MD markedly decreased LPS-stimulated TNF-alpha production, which was dose dependent and on the order of 96%-98%. Rising concentrations of NMD markedly inhibited lipid peroxidation by 59%-98%. Our results indicated that the inhibitory effect of NAS, NAD, NMD, or 4-O-MD on LPS-induced TNF-alpha production and FeCl(2)-stimulated lipid peroxidation is robust and dose dependent.

Synthesis, in vitro formation, and behavioural effects of glutathione regioisomers of alpha-methyldopamine with relevance to MDA and MDMA (ecstasy).

Administration of 3,4-methylenedioxymethamphetamine (MDMA) or 3,4-methylenedioxyamphetamine (MDA) to rats produces serotonergic nerve terminal degeneration. However, they are not neurotoxic when injected directly into the brain, suggesting the requirement for peripheral metabolism of MDMA to a neurotoxic metabolite. Alpha-methyldopamine (alpha-MeDA) is a major metabolite of MDA. There are indications that a glutathione metabolite of alpha-MeDA and/or 3,4-dihydroxymethamphetamine may be responsible for the neurotoxicity and some of the behavioural effects produced by MDMA and/or MDA. The present study details the synthesis, purification and separation of the 5-(glutathion-S-yl)-alpha-MeDA and 6-(glutathion-S-yl)-alpha-MeDA regioisomers of alpha-MeDA. Incubation of MDA with human liver microsomes demonstrated that production of both glutathione adducts are related to cytochrome P450 2D6 isoform activity. Following intracerebroventricular administration (180 nmol) of either GSH adduct into Dark Agouti or Sprague-Dawley rats only 5-(glutathion-S-yl)-alpha-MeDA produced behavioural effects characterised by hyperactivity, teeth chattering, tremor/trembling, head weaving, splayed posture, clonus and wet dog shakes. Pre-treatment with a dopamine receptor antagonist (haloperidol, 0.25 mg/kg; i.p.) attenuated hyperactivity, teeth chattering, low posture and clonus and potentiated splayed postural effects. These results indicate that MDA can be converted into two glutathione regioisomers by human liver microsomes, but only the 5-(glutathion-S-yl)-alpha-MeDA adduct is behaviourally active in the rat.

Amplified amplitudes of circadian rhythms and nighttime hypotension in patients with chronic fatigue syndrome: improvement by inopamil but not by melatonin.

Fatigue is an important symptom of a disturbed circadian rhythm. To date, no studies of circadian rhythms in patients with chronic fatigue syndrome (CFS) have been published. The objectives of the study were to study rhythms of heart rate and systolic and diastolic blood pressure in patients with chronic fatigue syndrome compared with age-matched normotensive controls and to study the effects of melatonin and inopamil on such rhythms. Ambulatory blood pressure (ABP) measurements (Space Lab, Inc, validated) of 18 patients with CFS were made according to the 1987 U.S. Center for Disease Control Criteria, and measurements of 12 age-matched normotensive controls were used in a cosinor analysis of the two groups. The effects of melatonin and inopamil on ABP were studied subsequently in four patients in an 8-week open-label evaluation. One patient was hypertensive (diastolic blood pressure > 90 mm Hg at least once every 4 hours), and was, therefore, excluded. The data of the remaining 17 patients (15 women, 2 men) revealed a significant 12-hour rhythm in heart rate and 24-hour rhythm in systolic and diastolic blood pressure with 95% confidence intervals not significantly different from sinusoidal patterns. Although these rhythms were synchronous with the control group rhythms, their amplitudes were not and showed, respectively, 2.8, 2.8, and 9.0 times the size of the control group rhythms (p < 0.001, p < 0.001, and p < 0.0001, respectively). Systolic blood pressures in the patients with CFS were consistently below 100 mm Hg during the nighttime. In a subsequent pilot study of four patients from the study population treated with melatonin 4 mg daily and inopamil 200 mg daily for 4 weeks, inopamil reduced nighttime hypotension (p < 0.05), whereas melatonin increased nighttime hypotension (p < 0.02). Patients with CFS have increased amplitudes of circadian rhythms and systolic blood pressures consistently below 100 mm Hg during the nighttime. Positive inotropic compounds may be beneficial in such patients, but melatonin may not be.

Effect of epinine on tension of human renal arteries.

BACKGROUND: The present study aimed to characterize the effects of epinine, the active metabolite of ibopamine on tension development in human renal arteries. METHODS AND RESULTS: Experiments were performed on isolated human renal arteries rings obtained during surgery due to kidney tumors (n = 12). Epinine concentration-dependently relaxed isolated precontracted (PGF2 alpha) human renal artery rings (P < 0.05) in the presence of phentolamine, as effectively (epinine -30 +/- 4 mN, dopamine -31 +/- 5 mN) and with the same potency as dopamine (epinine EC50 0.7 mumol/l (0.4-1.2 mumol/l), dopamine 0.5 mumol/l (0.2-1.7 mumol/l). This effect was antagonized by the specific D1-receptor-antagonist SCH 23390. Effective beta-adrenoceptor antagonistic concentrations of propranolol did not affect epinine-induced vasorelaxation. In the absence of alpha- and beta-adrenoceptor-antagonists the potency of epinine to contract renal artery rings was significantly higher compared to dopamine indicating a higher affinity of epinine to alpha-adrenoceptors. CONCLUSION: The present study provides evidence for direct vasodilatory effects of epinine via activation of D1-receptors on human renal arteries.

Estudo comparativo de ibopamina e captopril na insuficiência cardíaca leve e moderada: estudo duplo-cego / Comparative study between ibopamine and captopril in mild and moderate heart failure: a double-blind study

Objetivo - Avaliar os efeitos sobre sintomas, capacidade de exercício (teste de esforço) e resposta miocárdica (Eco e Holter) em pacientes com insuficiência cardíaca congestiva (ICC), em uso de captopril ou ibopamina. Métodos - Estudo duplo-cego, paralelo, randomizado, com 18 pacientes, 9 em cada grupo, acompanhados ambulatorialmente por 3 meses. Doze pacientes eram do sexo masculino, 6 do feminino, todos com ICC classe funcional II ou III. A idade variou de 27 a 67 (média 48,7) anos. Utilizou-se captopril 50mg e ibopamina 100mg, ambos três vezes ao dia. Resultados - Houve melhora clínica em ambos os grupos. Ao teste de esforço houve aumento do tempo de exercício de 9 para 17min e 12 para 16min com captopril e ibopamina, respectivamente. Ao estudo ecocardiográfico observou-se, respectivamente, para o grupo com captopril e ibopamina aumento do diâmetro diastólico do ventrículo esquerdo (VE) de 72 para 74 e de 74 para 75mm e aumento da fraçäo de ejeçäo do VE de 0,35 para 0,38 e de 0,35 para 0,39. A incidência de arritmia ventricular näo diferiu significativamente em ambos os grupos. Conclusäo - Os dados obtidos demonstram que o emprego de ibopamina melhora a funçäo cardíaca, aumentando o débito cardíaco e a fraçäo de ejeçäo e o tempo de exercício e näo aumenta a incidência de arritmia. O seu efeito é semelhante ao observado com o emprego de captopril

Endothelium dependent relaxation in two different models of chronic heart failure and the effect of ibopamine.

OBJECTIVES: The purpose was to relate endothelium dependent relaxation to neurohumoral and haemodynamic changes in rats with chronic heart failure. METHODS: Rats were submitted to either coronary ligation causing myocardial infarction or banding of the abdominal aorta (aortic stenosis), and comparisons were made with normal rats (n = 20 per group). Starting six weeks after surgery, half of the experimental animals received ibopamine and the other half served as controls and were given saline for another three weeks. After this, haemodynamic and neurohumoral variables were determined and the rats were killed. Rings of both the thoracic and abdominal aorta were studied in organ baths to measure their response to vasoactive agents. RESULTS: Increased plasma noradrenaline concentrations in rats with myocardial infarction and aortic stenosis were reduced by ibopamine. Blood pressure and heart rate, which were higher in rats with aortic stenosis than in rats with myocardial infarction and in normal rats, were unaffected by ibopamine. The maximal relaxation to sodium nitrite was depressed in the thoracic aorta from rats with myocardial infarction. The pIC50 of metacholine induced relaxation was smaller in the thoracic aorta from rats with myocardial infarction and aortic stenosis. By contrast, both pIC50 and the maximal relaxation (Emax) were increased in the abdominal aorta from rats with aortic stenosis, whereas Emax was smaller in rats with myocardial infarction. Ibopamine had no significant effects on these responses. CONCLUSIONS: Endothelium dependent relaxation to metacholine was selectively altered in rats with chronic heart failure due to aortic stenosis, probably because of differences in regional haemodynamics. In rats with myocardial infarction, however, endothelium dependent relaxation was impaired in both the thoracic and abdominal aorta. Ibopamine acted as a neurohumoral modulator by reducing increased noradrenaline concentrations but had no significant effect on either endothelium dependent or independent relaxation.

Stereostructure activity relationships of catecholamines on human platelet function.

The concentration-dependent effects of clonidine, isomers of epinephrine, norepinephrine (NE), isoproterenol, cobefrin and alpha-methyldopamine, and related desoxy analogs (epinine, dopamine, N-isopropyldopamine) were examined on human platelets. The rank order of aggregatory potency (pD2 values) was R(-)-epinephrine (6.3) greater than R(-)-NE (5.9) greater than (+/-)-erythro-cobefrin (5.3) greater than S(+)-epinephrine (4.7) = S(+)-NE (4.7) = clonidine (4.7) = dopamine (4.6) greater than epinine (4.4) greater than S(+)-alpha-methyldopamine (4.3) = R(-)-alpha-methyldopamine (4.3) greater than (+/-)-threo-cobefrin (3.7). The isoproterenol isomers and N-isopropyl-dopamine were inactive as agonists. In 9 of 16 platelet-rich plasma preparations, R(-)-epinephrine, R(-)-NE, and (+/-)erythro-cobefrin were agonists and the remaining analogs blocked R(-)-NE-induced aggregation with a rank order of inhibitory potencies (pKB values) of clonidine (6.2) greater than S(+)-alpha-methyldopamine (5.0) greater than dopamine (4.6) = R(-)-alpha-methyldopamine (4.4) greater than or equal to S(+)-NE (4.3) greater than N-isopropyldopamine (4.1) greater than S(+)-isoproterenol (3.7) = R(-)-isoproterenol (3.5). Each compound was also able to reverse prostaglandin E1 (PGE1) (0.1 microM)-induced blockade of the maximal aggregation response to ADP. At high concentrations, R(-)-isoproterenol was more potent than either the S(+)-isomer or desoxy analog, N-isopropyldopamine, in the reversal of PGE1 inhibition of ADP aggregation. Phentolamine blocked these alpha 2-adrenoceptor-mediated actions against PGE1 on ADP aggregation. The rank order of potency for the reversal of PGE1-mediated inhibition of ADP aggregation by these catecholamines was similar to that observed for platelet aggregation. Our results indicate that (i) the stereochemical requirements for the interaction of catecholamines with platelet alpha 2-adrenoceptors are in agreement with the Easson-Stedman hypothesis and other alpha-adrenoceptor tissues; (ii) catecholamines lacking a benzylic hydroxyl group in the R-configuration and/or possessing an N-isopropyl group were alpha 2-adrenoceptor antagonists; (iii) clonidine gave quantitatively different responses compared with catecholamines for interaction with alpha 2-adrenoceptors; and (iv) inhibition of platelet adenylate cyclase is correlated to the inhibition of epinephrine-induced aggregation response for this series of compounds.

Reduced disease in aged rats treated chronically with ibopamine, a catecholaminergic drug.

As part of preclinical safety testing for carcinogenicity, postpubertal (50 days old) rats were dosed (0, 30, 90 or 180 mg/kg/day) with ibopamine (N-methyldopamine, 0,0'-diisobutyroyl ester.HCl; SK&F 100168) for 730 consecutive days. Neoplastic and nonneoplastic lesions were identified histologically in all rats that died during the period of dosing, as well as in those that were killed after it was completed. Six neoplastic lesions (adrenal cortical, mammary, and pituitary adenoma, skin papilloma, pheochromocytoma and mammary adenocarcinoma) and five nonneoplastic lesions (chronic glomerulonephropathy, renal pelvic mineralization, hepatocellular proliferative nodule, galactoceles and chronic cardiomyopathy) were significantly reduced in a dose-related fashion in at least one sex of ibopamine-treated rats. In addition, age-related alopecia and atrophy of the adrenal zona glomerulosa were retarded by ibopamine treatment. Squamous cell skin carcinoma was the only lesion that was significantly (p less than 0.05) increased in the treated groups. Mortality during the study was not significantly different in treated and control groups, indicating that the lower incidence of disease in ibopamine-treated rats was a drug effect and not an artifact of differential survival. Although life span was not measured, ibopamine-treated rats had significantly less malignant lesions than controls at the end of dosing, suggesting a potentially positive effect of treatment on population survival. As the result of these beneficial effects, ibopamine may be useful for future study of factors affecting the occurrence of disease during aging.

A role for alternative pathway catecholamines in the regulation of steroidogenesis in cow luteal cells.

Incubation of bovine luteal cells with the alternative pathway catecholamines octopamine, synephrine and deoxyadrenaline at concentrations of 10(-6) to 10(-3) M enhanced the production of progesterone (P less than 0.05). Tryamine did not alter basal progesterone production (P greater than 0.05). Addition of noradrenaline and adrenaline at concentrations of 10(-4) to 10(-7) M significantly elevated the production of progesterone (P less than 0.05). The steroidogenic response to noradrenaline and adrenaline was greater than that for octopamine, synephrine and deoxyadrenaline (P less than 0.05). Response to both primary (10(-6) M) and alternative (10(-4) M) pathway catecholamines was inhibited by propranolol (10(-5) M, P less than 0.05) but not phentolamine (10(-5) M, P greater than 0.05). These results demonstrate that octopamine, synephrine and deoxyadrenaline can affect steroidogenesis by bovine luteal cells, and their action is mediated by beta-adrenergic receptors.

Hemodynamic evaluation during exercise test after acute and chronic ibopamine treatment in patients with congestive heart failure.

The hemodynamic effects of ibopamine (SB-7505), the orally active 3,4-diisobutyryl ester of N-methyldopamine, were studied in 12 patients with congestive heart failure (CHF) after acute dosing, after 20 days of maintenance therapy and after 20 days of drug discontinuation. Acute ibopamine administration increased at rest cardiac index (CI p less than 0.05) and stroke work index (SWI p less than 0.05), and reduced pulmonary capillary wedge pressure (PCWP), mean pulmonary arterial pressure (PAP), total systemic (SVR p less than 0.05) and pulmonary vascular resistance (PVR). These beneficial hemodynamic effects were maintained during supine bicycle exercise: CI and SWI increased more markedly (p less than 0.05) and PCWP increased at a lower extent (p less than 0.05) after ibopamine than on control conditions. PVR exhibited a more pronounced decrease (p less than 0.02), while SVR showed superimposable reductions before and after ibopamine. After chronic therapy with the drug, hemodynamics and left ventricular function again improved during exercise, while withdrawal of ibopamine resulted in hemodynamic deterioration. Heart rate and systemic arterial pressure did not change significantly after the drug. This study demonstrates that ibopamine is able to improve cardiac performance during exercise in CHF patients after both acute and chronic administration.

Effect of the orally absorbed dopamine analogue N-methyldopamine diisobutyric ester on plasma prolactin levels.

The effect of the diisobutyric ester of N-methyldopamine (Ibopamine) on plasma prolactin levels was investigated in normoprolactinaemic subjects and in hyperprolactinaemic patients with prolactin-secreting tumours or idiopathic hyperprolactinaemia. In hyperprolactinaemic states oral Ibopamine 50 mg induced a significant decrease in elevated plasma prolactin (PRL) levels, 30, 60 and 90 min after administration. The peak effect occurred at 90 min when the mean PRL level was 61% of its basal values.

Effects of dobutamine on cyclic AMP accumulation induced by the stimulation of dopamine receptors in rabbit retina in vitro.

Intact rabbit retinae were used for testing in vitro the potential activation of dopamine receptors by a new cardioactive sympathetic amine dobutamine. It was found that despite the structure relationship of dobutamine with other dopamine-analog, the pharmacological action of this compound is not comparable to that of apomorphine, N-methyl-dopamine and/or ADTN.

Studies on the mechanism of the positive inotropic action evoked by epinine on the rabbit isolated papillary muscle at different rates of beating.

1. Effects of epinine on cyclic AMP and contractility were investigated in rabbit papillary muscles driven at a rate of 0.5 or 2.0 Hz. 2. When the frequency of stimulation was increased from 0.5 to 2.0 Hz, the log dose-response curve for the positive inotropic effect of epinine was displaced to the left, whereas the maximum of the developed tension was not changed. 3. At both frequencies phentolamine (1 mumol/l) shifted the lower part of the log dose-response curve for epinine to the right, whereas pindolol (30 nmol/l) affected mainly the upper part. In the presence of both alpha- and beta-adrenoceptor antagonists, the whole curve was shifted to the right in a parallel manner. However, cocaine (30 mumol/l) did not significantly influence the log dose-response curve of epinine. 4. At 0.5 Hz a submaximal effective concentration of epinine (100 mumol/l) led to an approximately 100% increase of the cyclic AMP level after 60s; the same increase of the cyclic AMP level was induced at 2.0 Hz by one-third the concentration of epinine (30 mumol/l). 5. Phentolamine (1 mumol/l) did not affect the increase of the cyclic AMP level evoked by epinine, whereas pindolol (30 nmol/l) completely depressed it. 6. The present results indicate that epinine produces its positive inotropic effect through direct stimulation of myocardial alpha-adrenoceptors as well as beta-adrenoceptors, depending upon the concentration: in lower concentrations it acts mainly on alpha-adrenoceptors, whereas in higher concentrations it acts predominantly on beta-adrenoceptors. The positive inotropic effect through beta-adrenoceptor stimulation is mediated by cyclic AMP, while that through alpha-adrenoceptors is not.