The Effects of Estrogen and Raloxifene Treatment on Antioxidant Enzymes in Brain and Liver of Ovarectomized Female Rats

Recent studies documented that estrogen have antioxidant properties in-vitro, there are conflicting results on the effect of estrogen in vivo. We aimed to investigate the effects of estradiol and Raloxifene on the antioxidant enzyme [superoxide dismutase (SOD) and catalase (CAT)] activities and MDA...

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Published in:	Endocrine research Vol. 29; no. 2; pp. 183 - 189
Main Authors:	Özgönül, Mert, Öge, Ay in, Sezer, Ebru Demirel, Bayraktar, Firat, Sözmen, Eser Yildirim
Format:	Journal Article
Language:	English
Published:	England Informa UK Ltd 01-01-2003 Taylor & Francis
Subjects:	Analysis of Variance Animals Antioxidants - physiology Brain - enzymology Catalase Catalase - drug effects Estrogen Estrogens - pharmacology Ethinyl Estradiol - pharmacology Female In Vitro Techniques Liver - enzymology Ovariectomy Oxidoreductases - drug effects Raloxifene Raloxifene Hydrochloride - pharmacology Rats Rats, Sprague-Dawley Selective Estrogen Receptor Modulators - pharmacology Superoxide dismutase Superoxide Dismutase - drug effects
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Summary:	Recent studies documented that estrogen have antioxidant properties in-vitro, there are conflicting results on the effect of estrogen in vivo. We aimed to investigate the effects of estradiol and Raloxifene on the antioxidant enzyme [superoxide dismutase (SOD) and catalase (CAT)] activities and MDA levels in brain and liver homogenates of ovariectomized female rats. Twelve weeks after ovariectomy, female Sprague-Dawley rats (n = 26) were divided into three groups: (1) Ovariectomized placebo group (n = 6) was given physiologic saline. (2) Estrogen group (n = 10) was given Ethynyl estradiol, 0.1 mg kg sc. (3) Raloxifene group (n = 10) was given raloxifene, 1 mg kg sc during 8 weeks. Ten rats were used as naive controls without any treatment (Sham operated group, n = 10). Ovariectomy lead to an increase in the CAT activities in liver tissue samples compared to the sham group ( p = 0.056, Mann-Whitney test). While estrogen treatment reversed to normal levels of CAT activities, raloxifene remained as ineffective. Superoxide dismutase activities and MDA levels in liver were remained unchanged in all groups. There was no significant change in the brain tissue SOD and CAT activities between the control, ovariectomy, estrogen treated, and raloxifen treated groups. We determined an increase in MDA levels in brain of ovariectomised rat ( p = 0.02). While raloxifene treatment reversed to normal levels of MDA ( p = 0.008), estrogen treatment failed. Our data showed that estrogen may play a role in regulation of CAT and SOD activities in liver due to its antioxidative effects. We can suggest that estrogen and raloxifene exert their antioxidative effects in brain rather than liver. Since Raloxifene's effect is more clear than estradiol, raloxifene may be suggested primarily for treatment and or prevention of diseases which can be resulted from oxidative stress in postmenopausal women.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0743-5800 1532-4206
DOI:	10.1081/ERC-120022299