Alterations of the proteasome in the CA1 neurons after transient ischemia

Abstract

Objective To investigate the alteration of chaperonine hsp40 and its influence on delayed death of neurons in the CA1 region of hippocampus after transient cerebral ischemia. Method After transient global ischemia for 20 minutes, rat model was made. Following different lengths of reperfusion, all the 28 wistar rats were divided into sham-operation group,4 hour recovery group, 24 hour recovery group and 72 hour recovery group ( n = 7 rats in each group). Immunochemistry and laser scanning confocal microscopy were used to observe the distributional alteration of hsp40 in the neurons. Differential centrifuge and western blot assay were used to analyze the quantitative alteration of hsp40 and its redistribution in the neurons. Results Immunochemistry and laser scanning confocal microscopy showed the progressive reduction of hsp40 occurred at first in the cytosol, then in the nucleus until the death of all the neurons in the CA1 region died. Differential centrifuge and western blot assay showed the level of hsp40 decreased from 1.00 ± 0.21 to 0.23 ± 0.13 ( P ＜ 0.01 ) 24 hours after reperfusion; the quantity of hsp40 in the protein aggregates increased from 1.00±0.18 to 8.61 ± 1.89 (P ＜0.01 =24 h after reperfusion.Conclusions The reduction of hsp40 in the neurons of hippocampus CA1 region is an important role in protein aggregates formation. Key words: Transient ischemia; Hippocampus CA1 region; Delayed neuron death; Proteasome; Activity assay