Effects of estrogens on oxidative protein damage in plasma and tissues in ovariectomised rats

Abstract

Purpose: To assess estrogen-related changes in the redox status of the brain and liver proteins as well as the systemic oxidative stress in ovarectomised (OVX) rats Methods: Twelve-week-old, sexually mature female Sprague–Dawley rats (200-250g) were randomly divided into four groups: The following treatment combinations were administrated daily to all in 0.05 ml 96% ethanol solution by gastric gavage. (1) Sham operation (2) OVX rats (3) OVX rats [0.02 mg/kg/day of 17?-estradiol (E2) and 0.01 mg/kg/day of norethisterone acetate] (4) OVX rats [E2 (0.01 mg/kg/day) and drospirenon (0.02 mg/kg/day)]. Estrogen levels were determined using routine clinical-chemistry methods. We also measured protein oxidation parameters such as protein carbonyl (PCO), total thiol (T-SH) and the other oxidative stress markers malondialdehyde (MDA) and glutathione (GSH). Results: Ovariectomy resulted in abnormal elevation of plasma and tissue oxidative stress markers and changes in redox status of the proteins in tissue dependent manner. Supplementation of various estrogens combinations partially alleviated these abnormalities and restored redox homeostasis of proteins after the ovariectomy. Among the studied protein oxidation parameters, plasma and tissue PCO levels of the OVX rats were higher than those of the control groups (P < 0.01). Hormone replacement therapies (HRT) caused a decrease in PCO and MDA in both plasma and tissue of the OVX rats (P < 0.01). HRT in OVX rats decreased plasma MDA and increased liver and brain GSH (P < 0.01). Liver MDA levels of the Drospirenon-treated rats were lower than in the norethisterone acetate group (P < 0.01). On the other hand, Drospirenon increases brain GSH s more effectively than norethisterone acetate (P < 0.01). After bilateral oopherectomy, plasma and tissue T-SH levels decreased in the OVX group compared with control (P < 0.01). Norethisterone acetate increased plasma T-SH more effectively than Drospirenon (P < 0.05) Conclusions: The study showed the extent of oxidative protein damage (OPD) in this model of estrogen deficiency. The protective effect of estrogens against tissue specific OPD suggests that estrogens play an important role within the antioxidant defense systems in plasma, liver and brain. The exact molecular mechanisms leading to these findings are not yet completely known. Meanwhile, hormone replacement therapy for the prevention of OPD in a tissue specific manner may be required.

Repeatedly Heated Vegetable Oils and Lipid Peroxidation

“…In the present study, dietaries once heated and five times heated palm and soy oil for four months had significantly increased the plasma lipid peroxidation in ovariectomized female rats. The result is in agreement with other studies which also reported that in ovariectomized-induced estrogen deficiency, an increase in oxidative stress accompanied by a reduction in antioxidant status was seen [57][58]. A study by Sánchez-Rodríguez [59] had recently found that menopause could be one of the main risk factors for oxidative stress.…”

Effects of Hormone Replacement Therapy on Plasma and Tissue Fibrinolytic Activity in a Rat Model of Surgically Induced Menopause

“…e 17β-estradiol + drospirenone group lost more weight than the 17β-estradiol + norhisterone acetate group, likely due to the natriuretic properties of drospirenone (Table 1). e information in Table 1 is identical to that included in a previous study by our group [11].…”

“…Parameters and data regarding oxidative stress and brinolysis in the present study were derived from a previous study by our group [11].…”

“…e rats underwent either a bilateral ovariectomy or a sham surgical procedure via midline laparotomy incision under sterile conditions followed by appropriate closure of the incisions, as described elsewhere [11].…”

Carbonyl Formation in Erythrocyte Membrane Proteins During Aging in Humans

“…Owing to this unique feature, membrane proteins of aging erythrocytes are primary targets for ROS and RNS 14,15 . Erythrocyte membrane protein carbonyl content was found to increase in an age-related pattern indicating an increase in oxidative protein damage in elderly subjects (Fig.…”