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 journalArticlepeer-review

42 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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