The Aβ(25-35) fraction mimics the toxic effects of the complete peptide Aβ(1-42) because this decapeptide is able to cause memory impairment and neurodegenerative events. Recent evidence has shown that the injection of Aβ(25-35) into the temporal cortex (TCx) of the rat increases the nitric oxide (NO) pathways with several consequences, such as neuronal loss in rats. Our aim was to investigate the effects of each NOS isoform by the prior injection of NOS inhibitors before the injection of the Aβ(25-35). One month after the treatment, the animals were tested for their spatial memory in the radial maze. The hippocampus (Hp) and TCx were assessed for NO production, nitration of proteins (3-NT), astrocytosis (GFAP), and neuronal loss. Our findings show a significant impairment in the memory caused by Aβ25-35 injection. In contrast NOS inhibitors plus Aβ25-35 cause a protection yielding a high performance in the memory test and reduction of cell damage in the TCx and the Hp. Particularly, iNOS is the major source of NO and related to the inflammatory response leading to the memory deficits. The inhibition of iNOS is an important target for neuronal protection against the toxicity of the Aβ25-35 over the long term.

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