Original Contribution OXIDATIVE DAMAGE AND PROTECTION BY ANTIOXIDANTS IN THE FRONTAL CORTEX OF ALZHEIMER’S DISEASE IS RELATED TO THE APOLIPOPROTEIN E GENOTYPE CHARLES RAMASSAMY,* DIANA AVERILL, ² UWE BEFFERT, ‡ STEPHANE BASTIANETTO,* LOUISE THEROUX,* SUZANNE LUSSIER-CACAN, § JEFFREY S. COHN, § YVES CHRISTEN,  JEAN DAVIGNON, § R´ EMI QUIRION,* ,¶ and JUDES POIRIER* ,¶ *Neuroscience Division, Douglas Hospital Research Center, Verdun, Quebec, Canada; ² Chemistry–Biochemistry Department, Universite ´ du Quebec a ` Montre ´al, Montre ´al, Canada; ‡ Department of Neurology and Neurosurgery, McGill University, Montre ´al, Canada; § Institut de Recherche Clinique de Montre ´al, Montre ´al, Canada;  IPSEN Institute, Paris, France; and ¶ McGill Center for Studies in Aging, Douglas Hospital, Verdun, Quebec, Canada (Received 6 January 1999; Revised 13 April 1999; Accepted 29 April 1999) Abstract—A great number of epidemiological studies have demonstrated that the frequency of the 4 allele of the apolipoprotein E gene (APOE) is markedly higher in sporadic and in familial late onset Alzheimer disease (AD). In the frontal cortex of AD patients, oxidative damage is elevated. We address the hypothesis that the APOE genotype and reactive oxygen-mediated damage are linked in the frontal cortex of AD patients. We have related the APOE genotype to the levels of lipid oxidation (LPO) and to the antioxidant status, in frontal cortex tissues from age-matched control and AD cases with different APOE genotypes. LPO levels were significantly elevated in tissues from Alzheimer’s cases which are homozygous for the 4 allele of APOE, compared to AD 3/3 cases and controls. Activities of enzymatic antioxidants, such as catalase and glutathione peroxidase (GSH-PX), were also higher in AD cases with at least one 4 allele of APOE, while superoxide dismutase (SOD) activity was unchanged. In the frontal cortex, the concentration of apoE protein was not different between controls and AD cases, and was genotype independent. The Ginkgo biloba extract (EGb 761), the neurosteroid dehydroepiandrosterone (DHEA) and human recombinant apoE3 (hapoE3rec) were able to protect control, AD 3/3 and 3/4 cases against hydrogen peroxide/iron-induced LPO, while hapoE4rec was completely ineffective. Moreover, EGb 761 and DHEA had no effect in homozygous 4 cases. These results demonstrate that oxidative stress-induced injury and protection by antioxidants in the frontal cortex of AD cases are related to the APOE genotype. © 1999 Elsevier Science Inc. Keywords—Lipid peroxidation, Glutathione, Glutathione Peroxidase, Catalase, Apolipoprotein E concentration, Ginkgo biloba extract EGb 761, DHEA, Free radicals INTRODUCTION In the pathophysiology of Alzheimer’s disease (AD), at least four genes are implicated, such as (i) mutations of the amyloid precursor protein (APP) gene on chromo- some 21 [1,2], (ii) polymorphism of the apolipoprotein E gene (APOE) on chromosome 19 [3–5], and (iii) muta- tions in the presenilin 1 as well as presenilin 2 genes on chromosomes 14 and 1, respectively [6,7]. Human apoE is a 37-kDa protein and its polymor- phism, referred to as apoE2, -E3, or -E4, are products of three respective alleles 2, 3, and 4 [8]. This polymor- phism results in six different phenotypes in the popula- tion. ApoE3 is the most common isoform and contains cysteine and arginine at sites 112 and 158, respectively. ApoE4 has arginine whereas apoE2 has cysteine at both of these sites in the amino acid sequences [9,10]. The frequency of these alleles in the general population is 0.08, 0.78, and 0.14, for 4, 3, and 2, respectively [8]. Studies from many research teams showed that the fre- quency of the 4 allele of APOE is markedly increased in AD [3–5]. Since this discovery, the link between apoE and neuropathology has attracted new interest, and var- ious research targets have emerged trying to explain the Address correspondence to: Judes Poirier, McGill Center for Studies in Aging, Douglas Hospital Research Center, 6825 Boulevard Lasalle, H4H 1R3 Verdun, Quebec, Canada; Tel: (514) 761-6131 ext. 23947; Fax: (514) 888-4050; E-Mail: mcip@musica.mcgill.ca. Free Radical Biology & Medicine, Vol. 27, Nos. 5/6, pp. 544 –553, 1999 Copyright © 1999 Elsevier Science Inc. Printed in the USA. All rights reserved 0891-5849/99/$–see front matter PII S0891-5849(99)00102-1 544