, Volume 120, Issue 5, pp 605-621
Date: 10 Aug 2010

Pharmacologic reversal of neurogenic and neuroplastic abnormalities and cognitive impairments without affecting Aβ and tau pathologies in 3xTg-AD mice

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Abstract

In addition to the occurrence of numerous neurofibrillary tangles and Aβ plaques, neurogenesis and neuronal plasticity are markedly altered in Alzheimer disease (AD). Although the most popular therapeutic approach has been to inhibit neurodegeneration, another is to promote neurogenesis and neuronal plasticity by utilizing the regenerative capacity of the brain. Here we show that, in a transgenic mouse model of AD, 3xTg-AD mice, there was a marked deficit in neurogenesis and neuroplasticity, which occured before the formation of any neurofibrillary tangles or Aβ plaques and was associated with cognitive impairment. Furthermore, peripheral administration of Peptide 6, an 11-mer, which makes an active region of ciliary neurotrophic factor (CNTF, amino acid residues 146–156), restored cognition by enhancing neurogenesis and neuronal plasticity in these mice. Although this treatment had no detectable effect on Aβ and tau pathologies in 9-month animals, it enhanced neurogenesis in dentate gyrus, reduced ectopic birth in the granular cell layer, and increased neuronal plasticity in the hippocampus and cerebral cortex. These findings, for the first time, demonstrate the possibility of therapeutic treatment of AD and related disorders by peripheral administration of a peptide corresponding to a biologically active region of CNTF.

J. Blanchard carried out most of the work, i.e. treatment of the mice with Peptide 6, behavioral and immunohistochemical studies and data analysis, and wrote the manuscript. L. Wanka synthesized and purified the peptide 6. Y.-C. Tung and M. C. Cárdenas-Aguayo carried out the Western blot analysis for changes in level of tau and phospho-tau. F. M. LaFerla provided the breeding pairs of 3xTg-AD mice. K. Iqbal and I. Grundke-Iqbal conceived and directed all phases of the study, including the manuscript.