Glutamate-Mediated Inflammation and Neural Cell Injury

2 Glutamate-Mediated Inflammation and Neural Cell Injury 

The identity of factors released from damaged neurons to signal microglial cell activation may depend upon which type of neural cell is damaged, neuron versus glial, and on the the toxin or stimulus, glutamate versus /1-amyloid versus a-synuclein, and the nature of cellular death, apoptosis versus necrosis. Similarly, the molecular mechanisms and internal and external factors that modulate the dynamic aspects of acute and chronic inflammation in cell injury mediated by glutamate remain unclear. It also remains unclear to what extent inflammation is beneficial 

7 Mechanisms of Neural Injury Caused by Glutamate and Its Receptors 

Glutamate-mediated Ca2+ entry through NMDA at the plasma membrane level and mobilization of Ca2+from intracellular stores through PLC-mediated generation of PtdIns-3/J is indispensable for the basal NF-kB activity. Three cytosolic Ca2+ sensors, calmodulin, protein kinases C (PKC), and the p2 l(ras)/phosphatidylinositol 3-kinase (Ptdlns-3K)/Akt pathways, are simultaneously involved in the steps linking the Ca2+ to NF-kB activity (Lilienbaum and Israel, 2003 Marchetti et al., 2004 Lubin et al., 2005). Calmodulin modulates calcineurin, a Ca2+-dependent protein phosphatase, which plays a role in the basal NF-kB activity, whilst stimulation of both the calmodulin kinase II and Akt kinase pathways results in the up-regulation of the transcriptional potential of the p65 subunit of NF-/cB (Lilienbaum and Israel, 

In primary cultures of neonatal cerebellar granule neurons, all Ca2+ sensors, calmodulin, protein kinases C (PKC), and the p21(ras)/phosphatidylinositol 3 -kinase (Ptdlns-3K)/Akt pathway, converge towards NF-kB at the levels of nuclear translocation as well as transcription. The duration of NF-kB activation is a critical determinant for sensitivity toward excitotoxic stress and is dependent on the different upstream and downstream signaling associated with various kinases. This is in contrast to studies in non-neuronal cells, which either do not respond to Ca2+ or do not simultaneously activate all three cascades (Lilienbaum and Israel, 2003). Collective evidence suggests that brain inflammatory processes differ from systemic inflammation not only in the involvement of various types of neural cells but also in differences in response to second messengers. 

---