Immunohistochemical Detection of Apoptosis-Related Proteins in Gerbil Hippocampus Transient Cerebral Ischemia: Neuroprotective Effect of Pitavastatin

J J

doi:10.3844/ajbbsp.2005.212.225

Abstract

Delayed and selective neuronal damage was caused in the CA1 sector of hippocampus following 5 min of transient cerebral ischemia in gerbils. We investigated the immunohistochemical alterations of apoptosis-related proteins such as bcl-2α, bcl-xs/l, bax, cytochrome c, and active caspase 3 and TUNEL staining in the hippocampus at 1 and 5 hr and 1, 2, 5 and 14 days after transient cerebral ischemia in gerbils. We also examined the effect of 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor pitavastatin against the alterations of apoptosis-related proteins and TUNEL staining in the hippocampus after cerebral ischemia. The alterations of apoptosis-related proteins in the hippocampal CA1 sector were more pronounced than the changes of hippocampal CA3 sector and dentate gyrus after cerebral ischemia. The alterations of apoptosis-related proteins in the hippocampal CA1 sector after cerebral ischemia preceded the neuronal damage in this region. Furthermore, the study with TUNEL staining showed that a marked increase of TUNEL-positive nuclei was evident only in the hippocampal CA1 sector 5 days after cerebral ischemia. Our immunohistochemical study also showed that pitavastatin prevented the alterations of apoptosis-related proteins and the increase of TUNEL-positive nuclei in the hippocampal CA1 sector 5 days after cerebral ischemia. The present study indicates that transient cerebral ischemia in gerbils causes the mitochondrial-dependent apoptosis in the hippocampal CA1 sector. Furthermore, our present study demonstrates that pitavastatin can prevent the alterations of apoptosis-related proteins and the increase of TUNEL-positive nuclei in the hippocampal CA1 sector after cerebral ischemia. Thus our study provides novel therapeutic strategies in clinical stroke.

Highlights

There is increasing evidence that apoptosis, a form programmed cell death, plays a critical role in the regulation of development and maintenance of many adult tissues, including those of the nervous system[1]
We recently reported that pitavastatin can decrease the neuronal damage of the hippocampal CA1 sector in gerbils after transient cerebral ischemia[30,31]
No neuronal damage was detected in the gerbil hippocampus up to 2 days after transient cerebral ischemia

Summary

Introduction

There is increasing evidence that apoptosis, a form programmed cell death, plays a critical role in the regulation of development and maintenance of many adult tissues, including those of the nervous system[1]. Morphological and biochemical features of apoptosis has been reproducibly detected in the ischemic brain, including cell membrane protrusion, chromatin condensation, formation of apoptotic bodies, and internucleosomal DNA degradation[2,3,4,5]. In the central nervous system (CNS), bcl-2 protein is expressed in a large population of neurons during embryonic development[6,7], but levels are greatly reduced or undetectable in the majority of postomitotic CNS neurons of adult brains[8]. Several studies demonstrate that the cytochrome c-dependent apoptotic pathway contributes to the neuronal cell death after ischemia[911]. Cytochrome c release from mitochondria is an important event in other CNS injuries, such as brain trauma and spinal cord injury[12,13,14], the upstream events of cytochrome c release from mitochondria after transient cerebral ischemia are not yet fully understood

Methods

Results

Conclusion