The inhibition of monoamine oxidase activity by various antidepressants: differences found in various mammalian species.
The effects of the antidepressant drugs zimeldine, imipramine, maprotiline or nomifensine on mitochondrial monoamine oxidase (MAO) activity in mouse, rat, dog and monkey brains were compared in vitro. Mouse, rat, dog and monkey brain MAO-B activities were inhibited by zimeldine more potently than MAO-A activity. Imipramine inhibited MAO-B more potently than MAO-A activity in mouse and rat brains. When dog and monkey brains were investigated, MAO-A activity was inhibited more potently than MAO-B activity at high concentrations of imipramine, while at low concentrations, MAO-B activity was more potently inhibited. Maprotiline and nomifensine inhibited mouse and rat brain MAO-B activity more potently than MAO-A activity, while the inverse was true for dog and monkey brains. All four drugs are competitive inhibitors of MAO-A, but noncompetitive inhibitors of MAO-B in all animal brains. The respective Ki values of these reagents for monkey brain MAO-A and MAO-B were low compared to those of mouse, rat and dog. These results indicate that monkey brain MAOs are more sensitive to antidepressant drugs than those in rodent brain. (+info)
Repeated treatment with levoprotiline, a novel antidepressant, up-regulates histamine H1 receptors and phosphoinositide hydrolysis response in vivo.
The effects of repeated administration of levoprotiline, a novel type of tetracyclic antidepressant on histamine H1, muscarinic acetylcholine and alpha 1-adrenergic receptors and the response of phosphoinositide hydrolysis (PI) stimulated by histamine in the cortex of the rat brain were investigated. Histamine H1 receptors were up-regulated to 120% and PI response stimulated by histamine was enhanced to 160%-200% after repeated treatment with levoprotiline (20 mg/kg, i.p., once a day for 28 days) when compared to that of the saline-treated group. No significant alterations of muscarinic acetylcholine and alpha 1-adrenergic receptors were observed. This demonstrates that the repeated treatment with levoprotiline has prominent action on the regulation of histamine H1 receptors and PI response coupling to histamine H1 receptors in vivo. (+info)
Acute effects of maprotiline on learning, anxiety, activity and analgesia in male and female mice.
The acute effects of maprotiline (2.5, 5, 10, 15, 20 or 25 mg/kg) on learning, anxiety, activity and analgesia in male and female mice were evaluated. In addition to inhibitory avoidance learning, anxiety and locomotor activity were measured in the same animals using an elevated plus-maze. A study of the acute effects of maprotiline (15, 20 or 25 mg/kg) on analgesia was carried out in naive animals of both sexes. Maprotiline impaired inhibitory avoidance at doses of 15, 20 or 25 mg/kg. The highest dose produced an anxiolytic effect in females, and the doses of 20 and 25 mg/kg reduced locomotor activity. Analgesia was observed with the highest dose. The impairment of inhibitory avoidance by maprotiline would seem to be independent of the drug's influence on anxiety, is not shadowed by an instrumental performance deficit and, at least in the case of the highest dose, could be influenced by the drug's effects on analgesia. It is hypothesized that acquisition is the memory process principally affected by maprotiline, and in particular stimuli processing. The lack of sex differences in the effects of maprotiline on inhibitory avoidance supports the generalization of findings previously obtained only in males. (+info)
A case of neuroleptic malignant syndrome with acute renal failure after the discontinuation of sulpiride and maprotiline.
A 46-year-old man developed neuroleptic malignant syndrome with acute myoglobinuric renal failure after the discontinuation of sulpiride and maprotiline treatment. He showed the characteristic features of hyperpyrexia, altered consciousness, muscle rigidity, and autonomic dysfunction. Laboratory data showed lysis of skeletal muscle cells and renal impairment. Muscle biopsy revealed necrosis and regenerative changes in muscle fibers. Renal biopsy showed focal tubulitis and interstitial infiltration of small inflammatory cells. The combination of sulpiride and maprotiline has not previously been reported to be the cause of neuroleptic malignant syndrome and acute myoglobinuric renal failure. (+info)
Antidepressant stimulation of CDP-diacylglycerol synthesis does not require monoamine reuptake inhibition.
Automated determination of drugs in serum by column-switching high-performance liquid chromatography. IV. Separation of tricyclic and tetracyclic antidepressants and their metabolites.
We describe automated column-switching high-performance liquid chromatography for determining nine tricyclic and tetracyclic antidepressants (TCAs) and their metabolites in human serum. TSKgel ODS-80TM and TSKprecolumn PW (Tosoh Co., Tokyo) are used in the analytical column and the precolumn, respectively. A 200-microL serum sample is directly injected onto the precolumn. After washing the serum proteins from the precolumn with potassium phosphate buffer, the precolumn connection is switched to introduce the retained substances onto the analytical column. The drugs are then eluted within 30 min with an acetonitrile/potassium phosphate buffer mixture containing sodium 1-heptanesulfonate. The analytical recoveries (95-104%), reproducibilities (within-run CV less than 3%), and detection limits (10 micrograms/L) indicate that this HPLC system is suited for therapeutic drug monitoring. Correlations were good between the TCA concentrations in serum and administered dose (r = 0.713, n = 41), and between 10-hydroxynortriptyline and nortriptyline in serum (r = 0.691, n = 24). (+info)