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ABSTRACT: Abundant evidence suggests that indirect inhibitory modulation of glutamatergic transmission, via metabotropic glutamatergic receptors (mGluR), may induce neuroprotection. The present study was designed to determine whether the selective antagonist of mGluR1 (3-ethyl-2-methyl-quinolin-6-yl)-(4-methoxy-cyclohexyl)-methanone methanesulfonate (EMQMCM), showed neuroprotection against the kainate (KA)-induced excitotoxicity in vitro and in vivo. In in vitro studies on mouse primary cortical and hippocampal neuronal cultures, incubation with KA (150 μM) induced strong degeneration [measured as lactate dehydrogenase (LDH) efflux] and apoptosis (measured as caspase-3 activity). EMQMCM (0.1-100 μM) added 30 min to 6 h after KA, significantly attenuated the KA-induced LDH release and prevented the increase in caspase-3 activity in the cultures. Those effects were dose- and time-dependent. In in vivo studies KA (2.5 nmol/1 μl) was unilaterally injected into the rat dorsal CA1 hippocampal region. Degeneration was calculated by counting surviving neurons in the CA pyramidal layer using stereological methods. It was found that EMQMCM (5-10 nmol/1 μl) injected into the dorsal hippocampus 30 min, 1 h, or 3 h (the higher dose only) after KA significantly prevented the KA-induced neuronal degeneration. In vivo microdialysis studies in rat hippocampus showed that EMQMCM (100 μM) significantly increased γ-aminobutyric acid (GABA) and decreased glutamate release. When perfused simultaneously with KA, EMQMCM substantially increased GABA release and prevented the KA-induced glutamate release. The obtained results indicate that the mGluR1 antagonist, EMQMCM, may exert neuroprotection against excitotoxicity after delayed treatment (30 min to 6 h). The role of enhanced GABAergic transmission in the neuroprotection is postulated.
Neurotoxicity Research 12/2011; 21(4):379-92. · 3.51 Impact Factor
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ABSTRACT: Impairment of the ubiquitin-proteasome system, responsible for clearing of misfolded and unwanted proteins, has been implicated in the loss of nigrostriatal dopaminergic neurons characteristic of Parkinson's disease (PD). Recently, proteasome inhibitors have been used to model parkinsonian-like changes in animals. In the present study, the effects of intrastriatal and intranigral injections of the selective proteasome inhibitor lactacystin on key markers of PD were examined in Wistar rats. Comparisons of these two different routes of lactacystin administration revealed that only a unilateral, intranigral injection of lactacystin at a dose of 0.5, 1, 2.5 and 5μg/2μl produced after 7 days distinct decreases in the concentrations of dopamine (DA) and its metabolites (DOPAC, 3-MT, HVA) in the ipsilateral striatum. The used doses of lactacystin (except for 0.5μg/2μl) significantly accelerated DA catabolism, i.e. the total, oxidative MAO-dependent and COMT-catalyzed pathways, as assessed by HVA/DA, DOPAC/DA and 3-MT/DA ratios, respectively, in the ipsilateral striatum. Such alterations were not observed in the striatal DA content and catabolism either 7, 14 or 21 days after a unilateral, intrastriatal high-dose lactacystin injection (5 and 10μg/2μl). Intranigrally administered lactacystin (1μg/2μl) caused a marked decline of tyrosine hydroxylase (TH) and α-synuclein protein levels in that structure. Neither TH nor α-synuclein protein levels in the substantia nigra (SN) were affected by high lactacystin doses injected intrastriatally. Moreover, stereological counting of TH-immunoreactive neurons and autoradiographic analysis of [(3)H]GBR 12,935 binding to dopamine transporter confirmed a loss of nigrostriatal dopaminergic neurons after an intranigral lactacystin (1 and 2.5μg/2μl) injection. An appearance of cardinal neurochemical and histological changes of parkinsonian type only after intranigral lactacystin injection indicates that DA cell bodies in the SN, but not DA terminals in the striatum are susceptible to proteasome inhibition.
Neurochemistry International 03/2011; · 2.86 Impact Factor
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ABSTRACT: In the present study, we examined the anxiolytic-like effects of (1R,2R,3R,5R,6R)-2-amino-3-(3,4-dichlorobenzyloxy)-6fluorobicyclo[3.1.0]hexane-2,6-dicarboxylic acid (MGS0039), a mGluR2/3 antagonist, in the Vogel conflict drinking test in rats. MGS0039 administered at the doses of 1 and 2 mg/kg ip (yet not at 3 mg/kg) produced anxiolytic-like effects in this test. Diazepam (2.5-10 mg/kg) was used as a reference drug. In the second part of our experiment, MGS0039 was tested at an effective dose of 2 mg/kg after a mixed injection with ritanserin (5-HT(2A/C) receptor antagonist) and WAY100635 (5-HT(1A) receptor antagonist) or flumazenil (benzodiazepine receptor antagonist), and all of the compounds were found to attenuate the effect of MGS0039. The above results indicate that the mGluR2/3 antagonist MGS0039 may play a role in the therapy of anxiety and that its action may be mediated by serotonin and the GABAergic systems.
Pharmacological reports: PR 01/2011; 63(4):880-7. · 2.44 Impact Factor
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ABSTRACT: Several in vivo and in vitro studies have demonstrated the neuroprotective potential of pretreatment with 1alpha,25-dihydroxyvitamin D3 (calcitriol). The aim of the present study was to determine the effectiveness of calcitriol administered in vivo after a brain ischemic episode in the rat model of perinatal asphyxia, or when co-applied with or without delay during 24-h exposure of mouse hippocampal, neocortical and cerebellar neuronal cultures to glutamate on their 7th and 12th day in vitro (7 DIV and 12 DIV, respectively). Calcitriol was also administered after acute exposure of rat cerebellar neurons to glutamate. In 7-day-old rat pups subjected to hypoxia-ischemia, acute application of calcitriol in a single dose of 2 microg/kg, 30 min after termination of the insult, or subchronic, 7-day post-treatment with calcitriol, effectively reduced brain damage. The level of neuroprotection exceeded that achieved by hypoxic preconditioning used as the reference neuroprotective method. The results of in vitro experiments revealed the ability of calcitriol to reduce excitotoxicity in a manner dependent on the origin of the neuronal cells, their stage of maturation in culture and the duration of exposure to the excitotoxic insult before calcitriol application. Calcitriol was neuroprotective when it was administered together with glutamate or even after a delay of up to 6h during 24-h excitotoxic challenge of hippocampal and neocortical, but not cerebellar neuronal cultures. Application of calcitriol to cultured cerebellar granule neurons after acute exposure to glutamate was ineffective. In 12 DIV hippocampal cell cultures, 50 nM calcitriol inhibited glutamate-induced caspase-3 activity, while only 100 nM concentrations were effective in 7 DIV cultures. We ascribe the protective effects of calcitriol to the rapid modulation of mechanisms that are instrumental in the direct anti-apoptotic, neuroprotective action of this compound.
Neurochemistry International 10/2009; 55(5):265-74. · 2.86 Impact Factor
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ABSTRACT: It is generally assumed that neurodegeneration is connected with glutamatergic hyperactivity, and that neuropeptide Y (NPY) inhibits glutamate release. Some earlier studies indicated that NPY may have neuroprotective effect; however, the results obtained so far are still divergent, and the role of different Y receptors remains unclear. Therefore in the presented study we investigated the neuroprotective potential of NPY and its Y2, Y5 or Y1 receptor (R) ligands against the kainate (KA)-induced excitotoxicity in neuronal cultures in vitro, as well as in vivo after intrahippocampal KA injection and also in an ischemic middle cerebral artery occlusion model after intraventricular injection of Y2R agonist. NPY compounds were applicated 30 min, 1, 3 or 6 h after the start of the exposure to KA, or 30 min after the onset of ischemia. Our results indicate the neuroprotective activity of NPY and its Y2R and Y5R ligands against the kainate-induced excitotoxicity in primary cortical and hippocampal cultures. Importantly, NPY was effective when given as late as 6 h, while Y2R or Y5R agonists 3 h, after starting the exposure to KA. In in vitro studies those protective effects were inhibited by the respective receptor antagonists. Neuroprotection was also observed in vivo after intrahippocampal injection of Y2R and Y5R agonists 30 min or 1 h after KA. No protection was found either in vitro or in vivo after the Y1R agonist. The Y2R agonist also showed neuroprotective activity in the ischemic model. The obtained results indicate that neuropeptide Y produces neuroprotective effect via Y2 and Y5 receptors, and that the compounds may be effective after delayed application.
Neuropeptides 04/2009; 43(3):235-49. · 1.55 Impact Factor
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ABSTRACT: Corticotropin releasing factor (CRF) is a neuropeptide widely distributed in the brain. The role of CRF in the behavioural activity and modulation of anxiety states in several brain structures has been well documented, but its function in the cerebral cortex still remains unknown. The aim of our study was to investigate the effect of CRF injected bilaterally into rat frontal cortex on the locomotor and exploratory activity and anxiety of rats. We also examined the effect of CRF on extracellularly recorded field potentials in rat frontal cortical slices in vitro. Behavioural experiments showed that CRF in doses of 0.05, 0.1, 0.2 microg/1 microl/site decreased locomotor and exploratory activity during a 40-min session in the open field test. In the elevated plus-maze test, CRF in a dose of 0.2 microg/1 microl/site produced a significant anxiolytic-like effect, which was prevented by CRF receptor antagonists (alpha-helicalCRF(9-41) and NBI 27914). Electrophysiological experiments showed that CRF-induced a transient depression of field potentials in slices partly disinhibited by GABA(A) and GABA(B) receptors antagonists. The blockade of NMDA receptors prevented the occurrence of that effect. The obtained results suggest that CRF may have anxiolytic-like effects in the frontal cortex. Moreover, the peptide inhibits locomotor and exploratory activity and depresses excitatory synaptic transmission in a NMDA receptor-dependent manner.
Neuropeptides 08/2008; 42(5-6):513-23. · 1.55 Impact Factor
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ABSTRACT: Earlier studies conducted by our group and by other authors indicated that metabotropic glutamatergic receptor (mGluR) ligands might have anxiolytic activity and that amygdalar neuropeptide Y (NPY) neurons were engaged in that effect. Apart from the amygdala, the hippocampus, another limbic structure, also seems to be engaged in regulation of anxiety. It is rich in mGluRs and contains numerous NPY interneurons. In the present study, we investigated the anxiolytic activity of group II and III mGluR agonists after injection into the hippocampus, and attempted to establish whether hippocampal NPY neurons and receptors were engaged in the observed effects. Male Wistar rats were bilaterally microinjected with the group II mGluR agonist (2S,1'S,2'S)-2-(carboxycyclopropyl)glycine (L-CCG-I), group III mGluR agonist O-Phospho-L-serine (L-SOP), NPY, the Y1 receptor antagonist BIBO 3304, and the Y2 receptor antagonist BIIE 0246 into the CA1 or dentate area (DG). The effect of those compounds on anxiety was tested in the elevated plus-maze. Moreover, the effects of L-CCG-I and L-SOP on the expression of NPYmRNA in the hippocampus were studied using in situ hybridization method. It was found that a significant anxiolytic effect was induced by L-SOP injection into the CA1 region or by L-CCG-I injection into the DG. The former effect was inhibited by BIBO 3304, the latter by BIIE 0246. NPY itself showed antianxiety action after injection into both structures. In the CA1 area, the effect of NPY was prevented by BIBO 3304, whereas in the DG by BIIE 0246. Both the mGluR agonists L-CCG-I and L-SOP induced a potent increase in NPYmRNA expression in the DG region of the hippocampal formation. The obtained results indicate that group II and III mGluR agonists, L-CCG-I and L-SOP, as well as NPY display anxiolytic activity in the hippocampus, but act differently in the CA1 and DG. It was observed that group III mGluRs and Y1 receptors were engaged in the response in the CA1 area, whereas group II mGluRs and Y2 receptors played a pivotal role in the DG region.
Neuropsychopharmacology 07/2007; 32(6):1242-50. · 7.99 Impact Factor
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ABSTRACT: The majority of studies on neuroprotection tested potentially protective compounds given before, simultaneously or shortly after damage. Such procedures are greatly different from the situation faced in clinical practice. In the present study, we tried to find out whether two compounds, a selective mGluR5 antagonist 3-[(2-methyl-1, 3-thiazol-4-yl) ethynyl]-pyridine (MTEP) and neuro-peptide Y (NPY) elicit neuroprotective action against excitotoxic damage in the mouse neocortical and hippocampal neuronal cultures after delayed treatment. In order to evoke toxic effects, primary cultures were exposed to 150 munic acid (KA) for 24 h (hippocampus) or for 48 h (neocortex). MTEP (1, 10 and 100 microM), or NPY (0.5 microM and 1 microM) were applied 30 min before, or 30 min, 1 h, 3 h or 6 h after KA. Kainate neurotoxicity was measured by lactate dehydrogenase (LDH) efflux from the damaged cells into the culture media. The results of our studies showed that MTEPor NPY treatment attenuated the kainate-induced LDH release in mouse neocortical and hippocampal cultures. The effect was observed when the compounds were added not only before, but also 30 min to 6 h after KA. Moreover, both MTEP and NPY displayed antiapoptotic activity as they prevented the KA-induced increase in the expression of caspase-3 activity in the cultures under study. Summing up, our data showed that MTEP and NPY were neuroprotective in wide time schedule. The effectiveness of late treatment with these compounds opens a new perspective for their potential therapeutic use.
Pharmacological reports: PR 58(6):846-58. · 2.44 Impact Factor
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ABSTRACT: Extensive research into glutamate receptors in the central nervous system has shown important role of metabotropic glutamate receptors (mGluR) as potential targets for neuroprotective drugs. The aim of the present study was to investigate neuroprotective potential of the highly selective mGlu5 antagonist 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]-pyridine (MTEP) against kainate (KA)-induced excitotoxicity in vivo. Our attention was focused mainly on the effectiveness of delayed treatment. In order to evoke neuronal injury, rats were unilaterally injected with kainic acid (KA; 2.5 nmol/1 μl) into the CA1 region of the hippocampus. MTEP (1, 5 or 10 nmol/1 μl) was administered into CA1 30 min, 1, 3 and 6 h after KA. Additionally, other rats were injected intraperitoneally (i.p.) with MTEP in a dose of 1 mg/kg, once daily for 7 days. The first injection of MTEP was 1 h after KA. Seven days after treatment, the brains were taken out and analyzed histologically to estimate the total number of neurons in CA region of dorsal hippocampus using stereological methods. The study was also aimed at determining a possible influence of MTEP on neuronal glutamate release induced by KA in the hippocampus, using microdialysis method. The obtained results showed that MTEP had neuroprotective effect after both intrahippocampal and intraperitoneal injection. It was found that MTEP could prevent excitotoxic neuronal damage even when it was applied 1-6 h after the toxin. Moreover, it was observed that MTEP significantly reduced the KA-induced glutamate release in the hippocampus. It seems to play a role in mediating neuroprotective effects of MTEP.
Pharmacological reports: PR 62(6):1051-61. · 2.44 Impact Factor
