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Impairment by opipramol of isoprenaline lipolytic activation in human subcutaneous adipocytes. Isoprenaline was tested alone at increasing concentrations (iso alone, black circles, control) or in the presence of 100 μM opipramol (red squares). Spontaneous glycerol release from freshly isolated adipocytes (basal) was also tested without and with opipramol. Each point is the mean ± SEM of 8-9 determinations. Different from the corresponding control at *: p < 0.05; **: p < 0.01; ***: p < 0.001.
Source publication
Treatment with several antipsychotic drugs exhibits a tendency to induce weight gain and diabetic complications. The proposed mechanisms by which the atypical antipsychotic drug olanzapine increases body weight include central dysregulations leading to hyperphagia and direct peripheral impairment of fat cell lipolysis. Several investigations have r...
Contexts in source publication
Context 1
... serendipitous observation was that opipramol dramatically inhibited isoprenaline activation of lipolysis in human adipocytes. The sigmoid dose-response to the β-adrenergic agonist (characterized by an IC50 of 3.3 ± 1.9 nM) was flattened in the presence of 100 μM opipramol (Figure 2). . Impairment by opipramol of isoprenaline lipolytic activation in human subcutaneous adipocytes. ...
Context 2
... might explain why opiramole administration is not considered to induce weight gain in anxious patients. Nonetheless, our experiments indicated that, despite impairing the stimulation by various lipolytic agents, opipramol was not able to lower the baseline of glycerol release (see Figure 2). Indeed, testing the putative antilipolytic properties of any given agent in basal conditions is poorly relevant. ...
Citations
... All these considerations prompted us to test whether adrenaline and noradrenaline were activating glucose uptake in human adipocytes freshly isolated from pieces of abdominal subcutaneous adipose tissue removed during reconstructive surgery interventions in premenopausal women, as in [15,16]. When deciphering the effects of catecholamines in rat and mouse adipocytes, it has been evidenced that β-AR activation is not involved since catecholamines were able to activate glucose transport in fat cells from "beta-less" mice with triple knock-out of the subtypes of β-ARs[1]. ...
... Moreover, among the amines already reported to activate hexose uptake in human fat cells in the absence of insulin, it is worth mentioning benzylamine[17] and methylamine [15]. They are substrates of a copper-containing amine oxidase, the AOC3 gene of which is highly expressed in human fat cells: the semicarbazide-sensitive amine oxidase (SSAO) [18], also known as primary amine oxidase[19], or vascular adhesion protein-1[20]. ...
... Adipose tissue samples were transferred to the laboratory in less than an hour after surgery and cut into small pieces then digested at 37 °C by collagenase under agitation. Preparations of buoyant adipocytes were obtained by filtration of the digested pieces through nylon stockings and two washes with Krebs-Ringer buffered at pH 7.5 with 15 mmol/L sodium bicarbonate, 10 mmol/L HEPES, supplemented with 3.5% of bovine serum albumin, as in [15]. No freezing/thawing sequences were inserted in the protocol for obtaining functional adipocytes, and 2-DG uptake assays were completed within 5 h after each surgical intervention. ...
Background:
When combined with vanadium salts, catecholamines strongly activate glucose uptake in rat and mouse adipocytes.
Aim:
To test whether catecholamines activate glucose transport in human adipocytes.
Methods:
The uptake of 2-deoxyglucose (2-DG) was measured in adipocytes isolated from pieces of abdominal subcutaneous tissue removed from women undergoing reconstructive surgery. Pharmacological approaches with amine oxidase inhibitors, adrenoreceptor agonists and antioxidants were performed to unravel the mechanisms of action of noradrenaline or adrenaline (also named epinephrine).
Results:
In human adipocytes, 45-min incubation with 100 µmol/L adrenaline or noradrenaline activated 2-DG uptake up to more than one-third of the maximal response to insulin. This stimulation was not reproduced with millimolar doses of dopamine or serotonin and was not enhanced by addition of vanadate to the incubation medium. Among various natural amines and adrenergic agonists tested, no other molecule was more efficient than adrenaline and noradrenaline in stimulating 2-DG uptake. The effect of the catecholamines was not impaired by pargyline and semicarbazide, contrarily to that of benzylamine or methylamine, which are recognized substrates of semicarbazide-sensitive amine oxidase. Hydrogen peroxide at 1 mmol/L activated hexose uptake but not pyrocatechol or benzoquinone, and only the former was potentiated by vanadate. Catalase and the phosphoinositide 3-kinase inhibitor wortmannin inhibited adrenaline-induced activation of 2-DG uptake.
Conclusion:
High doses of catecholamines exert insulin-like actions on glucose transport in human adipocytes. At submillimolar doses, vanadium did not enhance this catecholamine activation of glucose transport. Consequently, this dismantles our previous suggestion to combine the metal ion with catecholamines to improve the benefit/risk ratio of vanadium-based antidiabetic approaches.
Opipramol is an active pharmaceutical ingredient used as an antidepressant and anxiolytic, being formulated as a dihydrochloride salt, usually in tablets and drops. The aim of the present study was represented by the thermal stability and kinetic evaluation of opipramol dihydrochloride (OPI 2HCl) performed in an oxidative atmosphere on the 30–450 °C temperature range using multiple heating rates (β = 2.5, 5, 7, 10 and 12 °C min−1). Thermogravimetric and derivative thermogravimetric analysis proved the stability of OPI 2HCl up until 150 °C followed by a single mass loss of approximately 80% up until 350 °C. A multi-process degradation was suggested by the differential scanning calorimetry evaluation and later confirmed by the use of the kinetic methods. The results were assessed using the preliminary ASTM E698 method, by means of which an apparent activation energy (Ea) value of 112.1 kJ min−1 was calculated. The implementation of the isoconversional Friedman differential method and Flynn–Wall–Ozawa integral method revealed a dependence of the Ea value to the conversion degree and an indication of a multistage decomposition responsible for the thermal degradation of the drug. As such, the nonparametric kinetics method was applied and a three-process degradation was revealed, all processes being determined by both physical transformations and chemical reactions.
The antidepressant drug opipramol has been reported to exert antilipolytic effect in human adipocytes, suggesting that alongside its neuropharmacological properties, this agent might modulate lipid utilization by peripheral tissues. However, patients treated for depression or anxiety disorders by this tricyclic compound do not exhibit the body weight gain or the glucose tolerance alterations observed with various other antidepressant or antipsychotic agents such as amitriptyline and olanzapine, respectively. To examine whether opipramol reproduces or impairs other actions of insulin, its direct effects on glucose transport, lipogenesis and lipolysis were investigated in adipocytes while its influence on insulin secretion was studied in pancreatic islets. In mouse and rat adipocytes, opipramol did not activate triglyceride breakdown, but partially inhibited the lipolytic action of isoprenaline or forskolin, especially in the 10-100 μM range. At 100 μM, opipramol also inhibited the glucose incorporation into lipids without limiting the glucose transport in mouse adipocytes. In pancreatic islets, opipramol acutely impaired the stimulation of insulin secretion by various activators (high glucose, high potassium, forskolin...). Similar inhibitory effects were observed in mouse and rat pancreatic islets and were reproduced with 100 μM haloperidol, in a manner that was independent from alpha2-adrenoceptor activation but sensitive to Ca2+ release. All these results indicated that the anxiolytic drug opipramol is not only active in central nervous system but also in multiple peripheral tissues and endocrine organs. Due to its capacity to modulate the lipid and carbohydrate metabolisms, opipramol deserves further studies in order to explore its therapeutic potential for the treatment of obese and diabetic states.
The activity of monoamine oxidase enzymes may be quantified by measuring the conversion of a radiolabeled amine substrate to a radiolabeled product that occurs during incubation of the substrate with the enzyme in an aqueous buffer. Described herein is an established discontinuous procedure in which separation of the substrate and product is achieved by extracting uncharged aldehydes into an organic solvent, while cationic amines remain in an acidified aqueous layer. Under assay conditions designed to ensure a pseudo-linear catalytic rate for the duration of the incubation, determination of radioactivity in the organic solvent by liquid scintillation counting facilitates estimation of an initial rate for amine turnover.Key wordsMonoamine oxidaseRadiolabeled amineOrganic extractionDiscontinuous assayLiquid scintillation counting5-HydroxytryptamineBenzylamine
