Profound and selective loss of catalytic TrkB immunoreactivity in Alzheimer's disease

Brain-derived neurotrophic factor (BDNF) is known to have trophic effects o n various neurons, throughout the brain and spinal cord, via its high-affin ity tyrosine kinase receptor TrkB. It has been reported that the mRNA for t his neurotrophin is reduced in Alzheimer's disease (AD) brain. We have exam ined, by Western blotting, the catalytic (p145) and noncatalytic or truncat ed (p95) forms of TrkB and find that, in both the temporal and frontal cort ex, there is a selective loss of immunoreactive-positive staining for the c atalytic or kinase form compared with the truncated form. This may have imp ortant consequences for the neurotrophic support of vulnerable neurons in A D. (C) 1999 Academic Press.