Characterizing the neuroprotective efficacy of ischemic preconditioning (ischemic tolerance) : is age an important factor?

Dowden, Jennifer (1999) Characterizing the neuroprotective efficacy of ischemic preconditioning (ischemic tolerance) : is age an important factor? Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

In this dissertation, the phenomenon of ischemic preconditioning was investigated in a gerbil model of global ischemia. Specifically, the neuroprotective efficacy of ischemic preconditioning was evaluated in aged and young gerbils to determine if age is an important factor influencing outcome. Outcome was assessed using histological, behavioural and electrophysiological endpoints in order to ensure an accurate measure of the extent of neuroprotection. -- In the first experiment, ischemic preconditioning was assessed in 18-20 month old gerbils. Ischemic preconditioning conveyed robust and long-lasting functional and histological protection. Furthermore, it appeared to be more effective than what had been previously reported in young animals (3-5 months). -- In the second experiment, a direct comparison of ischemic preconditioning protection was made in young (3-5 months old) and aged gerbils (18 months old). It was determined that aged animals had a higher level of protection compared to young animals. In addition, the results of this experiment suggest that one mechanism by which ischemic preconditioning produces protection may involve activation of astrocytes in the CA1 region. -- Finally, in the last experiment, the partial protection provided by ischemic preconditioning was used as a model to determine if early postishemic behavioural testing affected CA1 cell survival. In this study, there were no differences in cell counts between animals that had been exposed to a novel environment (open field apparatus) and those that were not.

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