Restraining tumor necrosis factor-alpha by thalidomide prevents the Amyloid beta-induced impairment of recognition memory in mice

No effective remedy has currently been realized to prevent the cognitive impairments of Alzheimer's disease (AD). The interruption of the toxic pathways of amyloid beta peptide (Aβ) still remains promising for the treatment. The involvement of tumor necrosis factor-alpha (TNF-α) in the toxicity of Aβ_1-40 in recent reports provide a fresh target for the interruption. In the current study, we evaluated the feasibility of a strategy that target TNF-α to prevent the impairment of memory induced by Aβ. The i.c.v-injection of Aβ_25-35 increased the hippocampal mRNA expression of both TNF-α and inducible nitric oxide synthase (iNOS), of which the former was stronger. The knock-out of TNF-α (TNF-α (-/-)) in mouse prevented the increase of iNOS mRNA induced by Aβ_25-35. Not only the inhibition of iNOS activity but also TNF-α (-/-) prevented the nitration of proteins in the hippocampus and the impairment of recognition memory in mice induced by Aβ_25-35. Daily treatment with thalidomide (20 mg/kg), a preferential degrader of TNF-α mRNA, or i.c.v.-injection of an anti-TNF-α antibody (10 ηg/mouse) prevented the nitration of proteins in the hippocampus and the impairment of recognition memory induced by Aβ_25-35 or Aβ_1-40 in mice. These results suggested the practicability of targeting TNF-α as a preventive strategy against Aβ-mediated cognitive impairments.