This chapter explores the application of gangliosides in the protection against glutamate excitotoxicity. In experimental studies, it is found that natural gangliosides and LIGA compounds in doses that reduce the increase of [3H] PDBU binding in the area penumbra and fail to block glutamate channel gating are completely ineffective in preventing the expression of the IEG. This suggests that IEG induction is the direct consequence of the Ca2+ influx through the glutamate gated ionotropic channel. In fact, stimulation with specific agonists of AMPA receptors that are less permeable to Ca2+ than NMDA receptors fail to induce IEG. It is concludes that natural and lysogangliosides also in vivo fail to modify the glutamate gating of ionotropic channels. These are blocked by MK801 which virtually abolishes IEG induction in the area penumbra. Thus, one can infer that the ganglioside block of Ca2+ amplification occurs downstream from the glutamate channel gating. Because MK801, the natural gangliosides and LIGA 4 and 20 reduce neuronal death in area penumbra, it is clear that excitotoxicity requires Ca2+ amplification mechanisms but not IEG induction.
Occasionally, multiple names are given to the same gene/protein. When this happens, different names can be used in subsequent publications, for example in different research areas, sometimes with little or no awareness that the same entity known under a different name may have a major role in another field of science. Recent reports about the protein p11 presented findings that this protein, commonly known as S100A10, may play a crucial role in depression and antidepressant treatment mechanisms. One set of data showed an increased expression of this protein in the brain of mice treated with antidepressants. P11/S100A10 is only one of several S100 proteins expressed in the brain. Interestingly, it has been previously noted that antidepressant treatment increases the brain content of another S100 protein, S100B. It appears that up-regulating the brain content of various S100 proteins might be a common feature of antidepressants. In cells coexpressing S100A10 and S100B, these proteins may interact and exert opposite regulatory roles. Nevertheless, S100A10 is predominantly expressed in certain types of neurons whereas S100B is more abundant in glia. Thus, an interplay among multiple members of the S100 proteins might be important in determining the region and cell specificity of antidepressant mechanisms. Calling the p11 protein by its other name, S100A10, may prompt more investigators from different fields to participate in this new direction of neurobiological research.