Antiarrhythmic and Electrophysiological Effects In-vivo of the Major Metabolite of Org 7797 Found in Canine and Rodent Liver Homogenate Preparations

Org 20781, the major metabolite of Org 7797 found in in-vitro experiments was examined for antiarrhythmic and electrophysiological effects in-vivo. Org 20781 (0·5–2·0 mg kg^?1 i.v.) inhibited the development of early ischaemia-induced arrhythmias in rats, suppressed spontaneous ventricular tachycardia (VT) in conscious dogs with 24-h old infarcts, and prevented electrical induction of VT in dogs with 5–6-day old infarcts, actions associated with slowing of conduction at all levels of the myocardium. Cardiac refractory periods were only modestly prolonged whilst repolarization was unchanged. Peak plasma levels of the parent compound (infused to total doses of 2–4mg kg^?1) associated with suppression of late arrhythmias were 6–18 μm, whilst the mean plasma elimination half-life (in normal dogs) was 107 min. It was concluded that the major metabolite has a similar antiarrhythmic and electrophysiological profile to the parent compound, is at least half as potent and may contribute to the therapeutic effects of Org 7797 administration.     

Antiarrhythmic activity of 17 beta-aminoestratrienes. Comparison of 3-ols and 3-acetates with the corresponding 3-(3-amino-2-hydroxypropyl) ethers

The antiarrhythmic efficacy of 17 beta-amino- and 17 beta-amino-16 alpha-hydroxyestratrien-3-ols and 3-acetates (group 1) was compared with the efficacy of corresponding 3-[2-hydroxy-3-(isopropylamino)propyl] and 3-[2-hydroxy-3-(tert-butylamino)propyl] ethers (group II), substituents which are usually associated with beta-adrenoceptor blocking activity. Group I compounds exerted potent antiarrhythmic activity against both aconitine-induced arrhythmias in mice and ischemia-induced arrhythmias in rats and reduced the maximum following frequency of isolated guinea pig atria. Electrophysiological studies indicated that their mechanism of action is due to an ability to reduce the fast inward sodium current in cardiac cells (class I antiarrhythmic action). Group II compounds were inactive in the aconitine and atrial tests and electrophysiological studies confirmed that they were devoid of class I activity. However, these compounds, like both class I antiarrhythmic and beta-adrenoceptor blocking drugs, were active against ischemia-induced arrhythmias. Group II compounds, unlike group I compounds, exerted nonspecific beta-adrenoceptor blocking actions, which may account for their activity in the rat test. It was concluded that introduction of the 3-substituted ether group did not confer any advantage over the parent 3-ol or 3-acetate compounds.     

Modulation of vocal and nonvocal behavior in adult squirrel monkeys by selective MAO-A and MAO-B inhibition

The acute effects of monoamine oxidase inhibitors L-deprenyl (0.5-5.0 mg/kg), clorgyline (1.0-10.0 mg/kg), and milacemide (100-400 mg/kg) on the behavior of adult male squirrel monkeys were examined during brief social separations beginning 60 min after subcutaneous drug administration. All three drugs selectively reduced the rate of calling during social separation at doses which did not affect time spent in locomotion, nor the frequency of vigilance-checking. Deprenyl and milacemide, but not clorgyline, produced concurrent decreases in locomotion at the higher doses tested. At threshold doses, clorgyline, but not deprenyl or milacemide, increased call duration and decreased call peak frequency compared to vehicle control values. Plasma levels of MHPG were decreased by an optimal dose of clorgyline but not by deprenyl or milacemide, indicating that substrate specificity was maintained at the drug doses employed. We conclude that different MAO substrates mediate different aspects of vocal and nonvocal behavior in adult male squirrel monkeys.     

Discovery of potent and selective inhibitors of procollagen C-proteinase for the treatment of fibrotic disorders

Introduction   Fibrosis is a component of many tissue pathologies leading to loss of normal tissue function, primarily due to excessive collagen deposition. Collagen is deposited following cleavage of the C- and N- terminal peptides from the pro-collagen molecule. The cleavage of the globular C-peptide by PCP reduces solubility of the fibrillar collagen molecule, resulting in deposition of insoluble collagen. Increased insoluble collagen deposition is a feature of all organ fibroses, with inhibition of this process, a key potential anti-fibrotic mechanism. The aim of this work was to discover potent and selective PCP inhibitors as experimental, topically applied, anti-fibrotic drugs for clinical evaluation.
Materials and methods   PCP was cloned from human osteosarcoma cells and enzymatic activity demonstrated using a PCP-specific peptide cleavage assay. Activities were confirmed by measuring cleavage of [³H]C-peptide from type-I pro-collagen. A cell-based fibroplasias model was employed to demonstrate compound efficacy using collagen deposition, liberated C-peptide and histological endpoints. The activities of PCP inhibitors in fibroblast and epithelial in vitro cell proliferation and migration assays, and selectivity vs. a panel of MMPs were also determined.
Discussion   In summary, we have identified and characterized potent and selective inhibitors of PCP for progression to clinical studies for investigation as a treatment paradigm for fibrotic disease.  

  Results     

10.

Modulation of fear-potentiated startle and vocalizations in juvenile rhesus monkeys by morphine, diazepam, and buspirone.     

James T Winslow  Pamela L Noble  Michael Davis 《Neuropsychopharmacology》2007,61(3):389-395

BACKGROUND: Modulation of the acoustic startle response by aversive sensory stimulation is a simple and objective indicator of emotionality in rodents and human beings that has been extremely valuable for the analysis of neural systems associated with fear and anxiety. We have described a paradigm for measuring fear-potentiated, whole-body acoustic startle in nonhuman primates and have developed a protocol for maintaining fear-potentiated startle over repeated sessions with minimal extinction to allow measurement of pharmacological effects on fear-potentiated startle by using within-subjects designs in relatively small groups of monkeys. METHODS: A novel, within-subjects testing protocol was used to examine the effects of three compounds in rhesus monkeys that have anxiolytic effects in rodents on fear-potentiated startle but that differ in their mechanism of action. Spontaneous vocalizations during testing also were recorded. Juvenile monkeys that were trained to associate a visual stimulus with a fear-inducing air blast to the face were tested after acute administration of different doses of buspirone diazepam, morphine, or vehicle. RESULTS: Monkeys rapidly developed a robust and persistent elevation of startle response in the presence of the CS during repeated testing sessions. Diazepam and morphine produced dose-related reductions of fear-potentiated startle. Buspirone did not significantly reduce fear-potentiated startle at the doses tested, although a trend was evident at the highest dose. All drugs reduced rates of coo vocalizations during startle testing. CONCLUSIONS: These fear-potentiated startle results suggest that rhesus monkeys have a pharmacological profile with respect to these compounds that is closer to humans than to rats. This demonstrates the value of examining the effects of drugs on fear-potentiated startle in nonhuman primates.     

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Modulation of fear-potentiated startle and vocalizations in juvenile rhesus monkeys by morphine, diazepam, and buspirone.

BACKGROUND: Modulation of the acoustic startle response by aversive sensory stimulation is a simple and objective indicator of emotionality in rodents and human beings that has been extremely valuable for the analysis of neural systems associated with fear and anxiety. We have described a paradigm for measuring fear-potentiated, whole-body acoustic startle in nonhuman primates and have developed a protocol for maintaining fear-potentiated startle over repeated sessions with minimal extinction to allow measurement of pharmacological effects on fear-potentiated startle by using within-subjects designs in relatively small groups of monkeys. METHODS: A novel, within-subjects testing protocol was used to examine the effects of three compounds in rhesus monkeys that have anxiolytic effects in rodents on fear-potentiated startle but that differ in their mechanism of action. Spontaneous vocalizations during testing also were recorded. Juvenile monkeys that were trained to associate a visual stimulus with a fear-inducing air blast to the face were tested after acute administration of different doses of buspirone diazepam, morphine, or vehicle. RESULTS: Monkeys rapidly developed a robust and persistent elevation of startle response in the presence of the CS during repeated testing sessions. Diazepam and morphine produced dose-related reductions of fear-potentiated startle. Buspirone did not significantly reduce fear-potentiated startle at the doses tested, although a trend was evident at the highest dose. All drugs reduced rates of coo vocalizations during startle testing. CONCLUSIONS: These fear-potentiated startle results suggest that rhesus monkeys have a pharmacological profile with respect to these compounds that is closer to humans than to rats. This demonstrates the value of examining the effects of drugs on fear-potentiated startle in nonhuman primates.