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Neuroprotective and anti-inflammatory roles of the phosphatase and tensin homolog deleted on chromosome Ten (PTEN) Inhibition in a Mouse Model of Temporal Lobe Epilepsy.

Grande V, Manassero G, Vercelli A - PLoS ONE (2014)

Bottom Line: Caused by an excess of glutamate that acts on metabotropic and ionotropic excitatory receptors, excitotoxicity activates several death signaling pathways leading to an extensive neuronal loss and a consequent strong activation of astrogliosis.Currently, the search for a neuroprotective strategy is aimed to identify the level in the signaling pathways to block excitotoxicity avoiding the loss of important physiological functions and side effects.We have demonstrated that inhibition of PTEN by bpv(pic) rescues neuronal death and decreases the reactive astrogliosis in the CA3 area of the hippocampus caused by systemic administration of kainate.

View Article: PubMed Central - PubMed

Affiliation: Neuroscience Institute Cavalieri Ottolenghi, Department of Neuroscience, University of Torino, Orbassano, Torino, Italy.

ABSTRACT
Excitotoxic damage represents the major mechanism leading to cell death in many human neurodegenerative diseases such as ischemia, trauma and epilepsy. Caused by an excess of glutamate that acts on metabotropic and ionotropic excitatory receptors, excitotoxicity activates several death signaling pathways leading to an extensive neuronal loss and a consequent strong activation of astrogliosis. Currently, the search for a neuroprotective strategy is aimed to identify the level in the signaling pathways to block excitotoxicity avoiding the loss of important physiological functions and side effects. To this aim, PTEN can be considered an ideal candidate: downstream the excitatory receptors activated in excitotoxicity (whose inhibition was shown to be not clinically viable), it is involved in neuronal damage and in the first stage of the reactive astrogliosis in vivo. In this study, we demonstrated the involvement of PTEN in excitotoxicity through its pharmacological inhibition by dipotassium bisperoxo (picolinato) oxovanadate [bpv(pic)] in a model of temporal lobe epilepsy, obtained by intraperitoneal injection of kainate in 2-month-old C57BL/6J male mice. We have demonstrated that inhibition of PTEN by bpv(pic) rescues neuronal death and decreases the reactive astrogliosis in the CA3 area of the hippocampus caused by systemic administration of kainate. Moreover, the neurotoxin administration increases significantly the scanty presence of mitochondrial PTEN that is significantly decreased by the administration of the inhibitor 6 hr after the injection of kainate, suggesting a role of PTEN in mitochondrial apoptosis. Taken together, our results confirm the key role played by PTEN in the excitotoxic damage and the strong anti-inflammatory and neuroprotective potential of its inhibition.

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PTEN inhibition protects CA3 neurons from kainate-induced excitotoxicity.Nissl-staining of hippocampus sections of mice treated with saline (A, control), with kainate (B, KA) or with both kainate and bpv(pic) (C, KA+I), killed one day after treatment (scale bar: 1 mm). A1. CA3 area of control animals (ctr) treated with saline only (scale bar: 50 µm). B1. CA3 area of animals treated with kainate (KA). Arrowheads point to apoptotic bodies and condensed nuclei as a consequence of kainate treatment. At higher magnification, a neuron that is degenerating. C1. CA3 area of animals treated with both kainate and PTEN inhibitor (KA+I). D. Immunostaining showing cleaved caspase-3 (in red) in neurons labeled with MAP-2 (in green) in the CA3 area of the hippocampus, one day after kainate administration. At higher magnification, arrowheads indicating neurons with a clear expression of cleaved caspase-3. Scale bar: 50 µm (30 µm at higher magnification). E. Surviving neurons in the hippocampal CA3 region. Histogram showing the linear density (cells/mm) of surviving neurons in the CA3 area of the hippocampus one day following kainic (KA) acid injection or kainic (KA) acid injection and PTEN inhibition (I) by bpv(pic) (KA+I). **P<0.01, §§P<0.01.
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pone-0114554-g001: PTEN inhibition protects CA3 neurons from kainate-induced excitotoxicity.Nissl-staining of hippocampus sections of mice treated with saline (A, control), with kainate (B, KA) or with both kainate and bpv(pic) (C, KA+I), killed one day after treatment (scale bar: 1 mm). A1. CA3 area of control animals (ctr) treated with saline only (scale bar: 50 µm). B1. CA3 area of animals treated with kainate (KA). Arrowheads point to apoptotic bodies and condensed nuclei as a consequence of kainate treatment. At higher magnification, a neuron that is degenerating. C1. CA3 area of animals treated with both kainate and PTEN inhibitor (KA+I). D. Immunostaining showing cleaved caspase-3 (in red) in neurons labeled with MAP-2 (in green) in the CA3 area of the hippocampus, one day after kainate administration. At higher magnification, arrowheads indicating neurons with a clear expression of cleaved caspase-3. Scale bar: 50 µm (30 µm at higher magnification). E. Surviving neurons in the hippocampal CA3 region. Histogram showing the linear density (cells/mm) of surviving neurons in the CA3 area of the hippocampus one day following kainic (KA) acid injection or kainic (KA) acid injection and PTEN inhibition (I) by bpv(pic) (KA+I). **P<0.01, §§P<0.01.

Mentions: Since it has been reported that systemic injection of KA resulted in a selective hippocampal neurodegeneration, especially in the CA3 area [27] for the highest density of KA receptors, we focused our analysis on this area. One day after KA stimulation, the thickness of the pyramidal cell layer in the CA3 was markedly decreased (Fig. 1B) compared to the control (Fig. 1A) whereas the application of PTEN inhibitor partially prevented the thinning of CA3 (Fig. 1C). Besides, as a consequence of the treatment with kainate, we also observed degenerating neurons with condensed nuclei that can be considered signs of apoptotic cell death in the CA3 area (see Fig. 1B1) as demonstrated by double immunofluorescence for MAP-2 (Microtubule-associated protein 2), a neuronal marker, and cleaved caspase-3, a marker of apoptosis, clearly expressed in neurons in the CA3 area after kainate treatment (Fig. 1D).


Neuroprotective and anti-inflammatory roles of the phosphatase and tensin homolog deleted on chromosome Ten (PTEN) Inhibition in a Mouse Model of Temporal Lobe Epilepsy.

Grande V, Manassero G, Vercelli A - PLoS ONE (2014)

PTEN inhibition protects CA3 neurons from kainate-induced excitotoxicity.Nissl-staining of hippocampus sections of mice treated with saline (A, control), with kainate (B, KA) or with both kainate and bpv(pic) (C, KA+I), killed one day after treatment (scale bar: 1 mm). A1. CA3 area of control animals (ctr) treated with saline only (scale bar: 50 µm). B1. CA3 area of animals treated with kainate (KA). Arrowheads point to apoptotic bodies and condensed nuclei as a consequence of kainate treatment. At higher magnification, a neuron that is degenerating. C1. CA3 area of animals treated with both kainate and PTEN inhibitor (KA+I). D. Immunostaining showing cleaved caspase-3 (in red) in neurons labeled with MAP-2 (in green) in the CA3 area of the hippocampus, one day after kainate administration. At higher magnification, arrowheads indicating neurons with a clear expression of cleaved caspase-3. Scale bar: 50 µm (30 µm at higher magnification). E. Surviving neurons in the hippocampal CA3 region. Histogram showing the linear density (cells/mm) of surviving neurons in the CA3 area of the hippocampus one day following kainic (KA) acid injection or kainic (KA) acid injection and PTEN inhibition (I) by bpv(pic) (KA+I). **P<0.01, §§P<0.01.
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pone-0114554-g001: PTEN inhibition protects CA3 neurons from kainate-induced excitotoxicity.Nissl-staining of hippocampus sections of mice treated with saline (A, control), with kainate (B, KA) or with both kainate and bpv(pic) (C, KA+I), killed one day after treatment (scale bar: 1 mm). A1. CA3 area of control animals (ctr) treated with saline only (scale bar: 50 µm). B1. CA3 area of animals treated with kainate (KA). Arrowheads point to apoptotic bodies and condensed nuclei as a consequence of kainate treatment. At higher magnification, a neuron that is degenerating. C1. CA3 area of animals treated with both kainate and PTEN inhibitor (KA+I). D. Immunostaining showing cleaved caspase-3 (in red) in neurons labeled with MAP-2 (in green) in the CA3 area of the hippocampus, one day after kainate administration. At higher magnification, arrowheads indicating neurons with a clear expression of cleaved caspase-3. Scale bar: 50 µm (30 µm at higher magnification). E. Surviving neurons in the hippocampal CA3 region. Histogram showing the linear density (cells/mm) of surviving neurons in the CA3 area of the hippocampus one day following kainic (KA) acid injection or kainic (KA) acid injection and PTEN inhibition (I) by bpv(pic) (KA+I). **P<0.01, §§P<0.01.
Mentions: Since it has been reported that systemic injection of KA resulted in a selective hippocampal neurodegeneration, especially in the CA3 area [27] for the highest density of KA receptors, we focused our analysis on this area. One day after KA stimulation, the thickness of the pyramidal cell layer in the CA3 was markedly decreased (Fig. 1B) compared to the control (Fig. 1A) whereas the application of PTEN inhibitor partially prevented the thinning of CA3 (Fig. 1C). Besides, as a consequence of the treatment with kainate, we also observed degenerating neurons with condensed nuclei that can be considered signs of apoptotic cell death in the CA3 area (see Fig. 1B1) as demonstrated by double immunofluorescence for MAP-2 (Microtubule-associated protein 2), a neuronal marker, and cleaved caspase-3, a marker of apoptosis, clearly expressed in neurons in the CA3 area after kainate treatment (Fig. 1D).

Bottom Line: Caused by an excess of glutamate that acts on metabotropic and ionotropic excitatory receptors, excitotoxicity activates several death signaling pathways leading to an extensive neuronal loss and a consequent strong activation of astrogliosis.Currently, the search for a neuroprotective strategy is aimed to identify the level in the signaling pathways to block excitotoxicity avoiding the loss of important physiological functions and side effects.We have demonstrated that inhibition of PTEN by bpv(pic) rescues neuronal death and decreases the reactive astrogliosis in the CA3 area of the hippocampus caused by systemic administration of kainate.

View Article: PubMed Central - PubMed

Affiliation: Neuroscience Institute Cavalieri Ottolenghi, Department of Neuroscience, University of Torino, Orbassano, Torino, Italy.

ABSTRACT
Excitotoxic damage represents the major mechanism leading to cell death in many human neurodegenerative diseases such as ischemia, trauma and epilepsy. Caused by an excess of glutamate that acts on metabotropic and ionotropic excitatory receptors, excitotoxicity activates several death signaling pathways leading to an extensive neuronal loss and a consequent strong activation of astrogliosis. Currently, the search for a neuroprotective strategy is aimed to identify the level in the signaling pathways to block excitotoxicity avoiding the loss of important physiological functions and side effects. To this aim, PTEN can be considered an ideal candidate: downstream the excitatory receptors activated in excitotoxicity (whose inhibition was shown to be not clinically viable), it is involved in neuronal damage and in the first stage of the reactive astrogliosis in vivo. In this study, we demonstrated the involvement of PTEN in excitotoxicity through its pharmacological inhibition by dipotassium bisperoxo (picolinato) oxovanadate [bpv(pic)] in a model of temporal lobe epilepsy, obtained by intraperitoneal injection of kainate in 2-month-old C57BL/6J male mice. We have demonstrated that inhibition of PTEN by bpv(pic) rescues neuronal death and decreases the reactive astrogliosis in the CA3 area of the hippocampus caused by systemic administration of kainate. Moreover, the neurotoxin administration increases significantly the scanty presence of mitochondrial PTEN that is significantly decreased by the administration of the inhibitor 6 hr after the injection of kainate, suggesting a role of PTEN in mitochondrial apoptosis. Taken together, our results confirm the key role played by PTEN in the excitotoxic damage and the strong anti-inflammatory and neuroprotective potential of its inhibition.

Show MeSH
Related in: MedlinePlus