Increased immunoreactivity of cdk5 activators in hippocampal sclerosis.

Cyclin-dependent kinase 5 is important in several in-vitro neurodegeneration paradigms. Whether cyclin-dependent kinase 5 contributes to cell death in human neurodegenerative diseases remains uncertain, particularly because post-mortem delay and other extrinsic factors might influence cyclin-dependent kinase 5 activity. Here we demonstrate increased immunoreactivity for the activators of cyclin-dependent kinase 5 in post-mortem human hippocampi affected by the neurodegenerative condition hippocampal sclerosis, but not in histologically normal hippocampi. Moreover, in post-mortem brain tissue from patients with unilateral hippocampal sclerosis, increased immunoreactivity for cyclin-dependent kinase 5 activators was detected in the hippocampus with sclerosis, but not in the contralateral hippocampus, suggesting that extrinsic factors are unlikely to account for the differential staining observed. Our findings suggest that deregulation of cyclin-dependent kinase 5 might contribute to the pathogenesis of hippocampal sclerosis.