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The changing face of neurotoxins
The Twenty-second Day of Neuropsychopharmacology Plenary lectures
Plenary lectures
Neuroprotective action of tianeptine against staurosporine- and doxorubicin-induced apoptosis: caspase-3-independent effect Danuta Jantas, W³adys³aw Lasoñ Department of Experimental Neuroendocrinology, Institute of Pharmacology, Polish Academy of Sciences, Smêtna 12, PL 31-343 Kraków, Poland
Tianeptine has been reported to possess anti-apoptotic properties against stress- and proinflammatory cytokines-induced cell damage in rodent brain as well in in vitro models of neuronal and glia cell degeneration. However, the molecular and cellular mechanism of neuroprotection mediated by this drug has been only partially unraveled. The aim of the present study was comparison of effectiveness of tianeptine and other antidepressants (imipramine, fluoxetine, citalopram, reboxetine, mirtazapine) in models of cell damage induced by activation of intracellular (staurosporine, St) and extracellular (doxorubicin, Dox) apoptotic pathways in primary cortical neurons and in retinoic acid-differentiated human neuroblastoma SH-SY5Y cell line. Tianeptine (0.01 and 0.1 μM) but not other antidepressants showed neuroprotective effects on St- and Dox-evoked cell death in primary neurons and in SH-SY5Y cells as confirmed by bio-
chemical analysis (LDH release and MTT reduction assays) and microscopic evaluation. The neuroprotection mediated by tianeptine was connected with attenuation of St- and Dox-induced DNA fragmentation but not with influence on St- and Dox-induced caspase-3 activity. The neuroprotective action of tianeptine was prevented by PI3-K (LY 294002) and MAPK/ERK1/2 (U0126) inhibitors. In the next part of the study on primary glia cells we demonstrated the protective effects of all tested antidepressants (0.1–10 μM) against the cell damage induced by Dox as was confirmed by MTT reduction assay. The present study showed that tianeptine but not other antidepressants clearly exerts neuroprotective effects. Moreover, the anti-apoptotic action of tianeptine in neuronal cells appears to engage PI3-K/Akt and MAPK/ERK1/2 survival pathways but is not connected with inhibition of caspase-3 activity.
The changing face of neurotoxins Richard M. Kostrzewa1, John P. Kostrzewa1, Ryszard Brus2 Department
of Pharmacology, Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA; Department of Nursing, High School of Strategic Planning, Koœcielna 6, PL 41-303 D¹browa Górnicza, Poland
Chemical neurotoxins, historically, have been regarded as agents able to produce nerve damage or overt neurodegeneration. Starting with the era of “selective neurotoxins” in the 1950s, neurotoxins have taken multiple forms, acting by a variety of mecha-
nisms: a) suppression of neurotrophins (anti-Nerve Growth Factor); b) production of intracellular reactive oxygen species (6-OHDA); c) formation of a toxic metabolite with specificity for mitochondrial complexes (MPTP ® MPP+); d) impairment of neuroPharmacological Reports, 2013, 65, suppl.
109
transmitter synthetic enzymes (DSP-4); e) inactivation of exocytosis (botulinum toxin); f) excitotoxin action at unique receptor types (kainate); g) evolution to a toxic species during continuous administration (cocaine); h) suicide inhibition of an intraneuronal enzyme (3-nitropropionate); inactivation of ribosomal protein (IgG-saporin); i) alkylation of the neuronal transporter site (ethylcholine aziridinium); j) desensitization of membranous receptors (capsaicin). The list is not exclusive, and it has the caveat that many neurotoxins act by multiple means. Surely, many other neurotoxins are yet to be discovered, and actions are destined to be at sites not yet known. Also, the term “selective neurotoxin” is entering a grey zone. Rote-
none, a mitochondrial poison in any cell, is now given long-term to specifically model Parkinson’s disease – an outcome marked by dopaminergic neuronal damage accompanied by alpha-synuclein deposits. Nmethyl-D-aspartate receptor (NMDA-R) antagonists, known neuroprotectants, become neurotoxic when administered during ontogeny. And the dopamine D2-R agonist quinpirole, when administered repeatedly, produces life-long D2-R supersensitivity – a neurotoxic outcome unaccompanied by any sign of overt neuronal damage. The character and definition of a selective neurotoxin is amorphous, and is likely to become more uncertain in the future.
Neuroprotective effects of statins during ischemic stroke Jacek Kurzepa Department of Biochemistry and Molecular Biology, Medical University of Lublin, Jaczewskiego 8, PL 20-090 Lublin, Poland
Ischemic stroke is the third leading cause of death and patients’ disability in industrialized countries. The stroke prevention, as well as a successful neuroprotection during acute brain ischemia, is one of the urgent problems of the current pharmacology. Inhibitors of HMG-CoA reductse (statins) are widely applied as a cholesterol-lowering drug. Numerous studies strongly suggest that the therapy with statins plays a role in stroke prevention mostly due to the protection against carotid atherosclerosis. Statins, besides the antilipemic properties, posses numerous pleiotropic activities that can bring the benefits during the acute phase of ischemic stroke. Among several proposed mechanisms of statins neuroprotective activity, the most important are: an increase in nitric oxide bioavailability (regulation of cerebral perfusion and
110
Pharmacological Reports, 2013, 65, suppl.
improvement of endothelial function), antioxidant properties and anti-inflammatory effects. In animal models of stroke the administration of statins, before the onset of cerebrovascular event, significantly decreases the ischemic focus volume. The early statins treatment from the first day of stroke results in the decrease of serum level of proinflammatory compounds as TNFa, IL-6. The serum levels of CRP, MMP-9/ TIMP-1 ratio and tau protein (the biomarker of neurons damage) are also decreased in comparison with non-statins patients. Despite the clear effect on biochemical parameters during the acute phase of ischemic stroke, statins effect on patients clinical outcome met the same fate as other potential neuroprotective compounds – is uncertain.
Plenary lectures
Neuroprotective action of tianeptine against staurosporine- and doxorubicin-induced apoptosis: caspase-3-independent effect Danuta Jantas, W³adys³aw Lasoñ Department of Experimental Neuroendocrinology, Institute of Pharmacology, Polish Academy of Sciences, Smêtna 12, PL 31-343 Kraków, Poland
Tianeptine has been reported to possess anti-apoptotic properties against stress- and proinflammatory cytokines-induced cell damage in rodent brain as well in in vitro models of neuronal and glia cell degeneration. However, the molecular and cellular mechanism of neuroprotection mediated by this drug has been only partially unraveled. The aim of the present study was comparison of effectiveness of tianeptine and other antidepressants (imipramine, fluoxetine, citalopram, reboxetine, mirtazapine) in models of cell damage induced by activation of intracellular (staurosporine, St) and extracellular (doxorubicin, Dox) apoptotic pathways in primary cortical neurons and in retinoic acid-differentiated human neuroblastoma SH-SY5Y cell line. Tianeptine (0.01 and 0.1 μM) but not other antidepressants showed neuroprotective effects on St- and Dox-evoked cell death in primary neurons and in SH-SY5Y cells as confirmed by bio-
chemical analysis (LDH release and MTT reduction assays) and microscopic evaluation. The neuroprotection mediated by tianeptine was connected with attenuation of St- and Dox-induced DNA fragmentation but not with influence on St- and Dox-induced caspase-3 activity. The neuroprotective action of tianeptine was prevented by PI3-K (LY 294002) and MAPK/ERK1/2 (U0126) inhibitors. In the next part of the study on primary glia cells we demonstrated the protective effects of all tested antidepressants (0.1–10 μM) against the cell damage induced by Dox as was confirmed by MTT reduction assay. The present study showed that tianeptine but not other antidepressants clearly exerts neuroprotective effects. Moreover, the anti-apoptotic action of tianeptine in neuronal cells appears to engage PI3-K/Akt and MAPK/ERK1/2 survival pathways but is not connected with inhibition of caspase-3 activity.
The changing face of neurotoxins Richard M. Kostrzewa1, John P. Kostrzewa1, Ryszard Brus2 Department
of Pharmacology, Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA; Department of Nursing, High School of Strategic Planning, Koœcielna 6, PL 41-303 D¹browa Górnicza, Poland
Chemical neurotoxins, historically, have been regarded as agents able to produce nerve damage or overt neurodegeneration. Starting with the era of “selective neurotoxins” in the 1950s, neurotoxins have taken multiple forms, acting by a variety of mecha-
nisms: a) suppression of neurotrophins (anti-Nerve Growth Factor); b) production of intracellular reactive oxygen species (6-OHDA); c) formation of a toxic metabolite with specificity for mitochondrial complexes (MPTP ® MPP+); d) impairment of neuroPharmacological Reports, 2013, 65, suppl.
109
transmitter synthetic enzymes (DSP-4); e) inactivation of exocytosis (botulinum toxin); f) excitotoxin action at unique receptor types (kainate); g) evolution to a toxic species during continuous administration (cocaine); h) suicide inhibition of an intraneuronal enzyme (3-nitropropionate); inactivation of ribosomal protein (IgG-saporin); i) alkylation of the neuronal transporter site (ethylcholine aziridinium); j) desensitization of membranous receptors (capsaicin). The list is not exclusive, and it has the caveat that many neurotoxins act by multiple means. Surely, many other neurotoxins are yet to be discovered, and actions are destined to be at sites not yet known. Also, the term “selective neurotoxin” is entering a grey zone. Rote-
none, a mitochondrial poison in any cell, is now given long-term to specifically model Parkinson’s disease – an outcome marked by dopaminergic neuronal damage accompanied by alpha-synuclein deposits. Nmethyl-D-aspartate receptor (NMDA-R) antagonists, known neuroprotectants, become neurotoxic when administered during ontogeny. And the dopamine D2-R agonist quinpirole, when administered repeatedly, produces life-long D2-R supersensitivity – a neurotoxic outcome unaccompanied by any sign of overt neuronal damage. The character and definition of a selective neurotoxin is amorphous, and is likely to become more uncertain in the future.
Neuroprotective effects of statins during ischemic stroke Jacek Kurzepa Department of Biochemistry and Molecular Biology, Medical University of Lublin, Jaczewskiego 8, PL 20-090 Lublin, Poland
Ischemic stroke is the third leading cause of death and patients’ disability in industrialized countries. The stroke prevention, as well as a successful neuroprotection during acute brain ischemia, is one of the urgent problems of the current pharmacology. Inhibitors of HMG-CoA reductse (statins) are widely applied as a cholesterol-lowering drug. Numerous studies strongly suggest that the therapy with statins plays a role in stroke prevention mostly due to the protection against carotid atherosclerosis. Statins, besides the antilipemic properties, posses numerous pleiotropic activities that can bring the benefits during the acute phase of ischemic stroke. Among several proposed mechanisms of statins neuroprotective activity, the most important are: an increase in nitric oxide bioavailability (regulation of cerebral perfusion and
110
Pharmacological Reports, 2013, 65, suppl.
improvement of endothelial function), antioxidant properties and anti-inflammatory effects. In animal models of stroke the administration of statins, before the onset of cerebrovascular event, significantly decreases the ischemic focus volume. The early statins treatment from the first day of stroke results in the decrease of serum level of proinflammatory compounds as TNFa, IL-6. The serum levels of CRP, MMP-9/ TIMP-1 ratio and tau protein (the biomarker of neurons damage) are also decreased in comparison with non-statins patients. Despite the clear effect on biochemical parameters during the acute phase of ischemic stroke, statins effect on patients clinical outcome met the same fate as other potential neuroprotective compounds – is uncertain.