In common with CBD, calretinin may be neuroprotective. In Alzheimer's disease, large pyramidal neuronal cells show a differential susceptibility to degeneration, and specific subpopulations, which express calretinin, might be resistant to degeneration (Hof et al. 1993). The presence of calretinin also seems to provide some protection against serum deprivation of rat cerebral cortex organ cultures (Weisenhorn et al. 1996).
A study of the expression of calretinin, together with CBD and PV mRNA, in hamster brain in relation to ageing, has also helped to focus attention on differences between calretinin and other CBPs. Kishimoto et al. (1998) found that whereas CBD transcript levels fell by 50 to 68%, calretinin and PV transcripts remained unchanged. Implicit in these findings is the suggestion that the down-regulation of CBD expression associated with the ageing process might reflect the neuroprotective action of CBD, and further, by inference, that calretinin may not function in this way. However, it ought to be recognised that most of the available evidence is too preliminary in nature to warrant conclusive interpretation.
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