A high soy diet reduces programmed cell death and enhances bcl-xL expression in experimental stroke

T. Lovekamp-Swan, M. Glendenning, D. A. Schreihofer

Research output: Contribution to journalArticle

41 Scopus citations

Abstract

Soy phytoestrogens have been proposed as an alternative to estrogen replacement therapy and have demonstrated potential neuroprotective effects in the brain. We have shown that a high soy diet significantly reduces infarct size following permanent middle cerebral artery occlusion (MCAO). Here, we tested the hypothesis that a high soy diet would attenuate programmed cell death after stroke. Adult female Sprague-Dawley rats were ovariectomized and fed either an isoflavone-reduced diet (IFP) or a high soy diet (SP) for 2 weeks before undergoing 90 min of transient middle cerebral artery occlusion (tMCAO) followed by 22.5 h reperfusion. Infarct size, as assessed by triphenyltetrazolium chloride staining, was significantly reduced by a high soy diet (P<0.05). Apoptosis in the ischemic cortex, measured by TUNEL staining, was significantly reduced by the high soy diet. The number of active caspase-3 positive cells and caspase-mediated α-spectrin cleavage were also significantly decreased in the ischemic cortex of SP rats. Furthermore, nuclear translocation of apoptosis-inducing factor (AIF) was significantly reduced in the ischemic cortex of SP rats. Soy significantly increased bcl-xL mRNA and protein expression in the ischemic cortex compared with IFP rats. Immunohistochemistry revealed increased neuronal expression of bcl-2 and bcl-xL in the ischemic cortex of both IFP and SP rats following tMCAO. These results suggest that a high soy diet decreases both caspase-dependent and caspase-independent programmed cell death following tMCAO. Further, a high soy diet enhances expression of the cell survival factor bcl-xL following tMCAO, contributing to the neuroprotective effects of soy in the ischemic cortex.

Original languageEnglish
Pages (from-to)644-652
Number of pages9
JournalNeuroscience
Volume148
Issue number3
DOIs
StatePublished - 7 Sep 2007

Keywords

  • apoptosis
  • bcl-2
  • caspase-3
  • neuroprotection

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