The effects of 17beta-estradiol and vitamin E treatments on oxidative stress and antioxidant levels in brain cortex of diabetic ovariectomized rats

Iron accumulation deteriorated bone loss in estrogen-deficient rats

Background

Postmenopausal osteoporosis is characterized by an imbalance of bone resorption exceeding bone formation, resulting in a net loss of bone mass. Whether a menopause-related excess of iron contributes to the development of postmenopausal osteoporosis has remained unresolved due to a lack of an appropriate animal model. This study aimed to explore the effects of iron accumulation in bone mass in estrogen-deficient rats.

Methods

In the present study, ovariectomy (OVX) was performed in female rats and the changes of iron metabolism and some related modulated genes were detected. Ferric ammonium citrate (FAC) was used as a donor of iron for OVX rats. Moreover, micro-CT was performed to assess the bone microarchitecture in sham group, OVX, and FAC groups. Histological detection of iron in liver was assessed by Perl’s staining. The expressions of β-CTX and osteocalcin were assessed by ELISA.

Results

It was found that serum iron decreased after OVX. It was found that the expressions of Hepcidin in liver and Fpn, DMT-1 in duodenum significantly decreased at transcriptional level in OVX group than sham group. However, no difference existed in the expression of DMT-1. Then, ferric ammonium citrate (FAC) was used as a donor of iron for OVX rats. The FAC group manifested significant iron accumulation by increased serum iron and hepatic iron content. In addition, FAC treatment accelerated bone loss and decreased BMD and biomechanics in OVX rats. Moreover, bone biomarker β-CTX rather than osteocalcin increased significantly in FAC groups than OVX group.

Conclusions

In conclusion, no iron accumulation occurred in OVX rats. Furthermore, iron accumulation could further deteriorate osteopenia through enhanced bone resorption.

Neuroprotective and Memory-Enhancing Effect of the Combined Extract of Purple Waxy Corn Cob and Pandan in Ovariectomized Rats

The neuroprotectant and memory enhancer supplement for menopause is required due to the side effects of hormone replacement therapy. Since purple waxy corn cob and pandan leaves exert antioxidant and acetylcholinesterase inhibition (AChEI) effects, we hypothesized that the combined extract of both plants (PCP) might provide synergistic effect leading to the improved brain damage and memory impairment in experimental menopause. To test this hypothesis, female Wistar rats were ovariectomized bilaterally and orally given various doses of the functional drink at doses of 20, 40, and 80 mg/kg for 28 days. The animals were assessed nonspatial memory using object recognition test every 7 days throughout the study period. At the end of study, they were assessed with oxidative stress status, AChEI, neuron density, and ERK1/2 signal in the prefrontal cortex (PFC). Interestingly, all doses of PCP increased object recognition memory and neuron density but decreased oxidative stress status in PFC. Low dose of PCP also decreased AChE activity while medium dose of PCP increased phosphorylation of ERK1/2 in PFC. Therefore, the improved oxidative stress status and cholinergic function together with signal transduction via ERK in PFC might be responsible for the neuroprotective and memory-enhancing effects of PCP.

The Appraisement of Antioxidant and Oxidant Status in Women Undergoing Surgical Menopause

The present study was undertaken to study the impact of surgical menopause on oxidant and antioxidant status in relation to estrogen levels after 3 months of surgery. Total 130 women who had undergone total hysterectomy (TH) with or without bilateral salpingo-oophorectomy (BSO) were included in this study. The oxidant status was assessed by measuring plasma levels of malondialdehyde and antioxidant status was assessed by measuring superoxide dismutase, catalase, glutathione, glutathione peroxidase, estrogen, and Vitamin A, E and C levels. The malondialdehyde level was significantly increased (p < 0.05) in all women who underwent TH with or without BSO. Significant increased levels of superoxide dismutase were observed in women who underwent TH with BSO. The blood glutathione levels were significantly decreased in women after TH only but significantly increased in women who had undergone TH with BSO. The levels of estrogen, vitamin E and vitamin C were significantly decreased in women who underwent TH with BSO. The catalase, GPx and vitamin A did not differ significantly in all groups. The result suggests that surgical menopause is associated with oxidative stress which reiterates the fact that ovaries retain some function even after menopause.

Protective Effect of Vitamins C and E on Depot-Medroxyprogesterone Acetate-Induced Ovarian Oxidative Stress In Vivo

A study was designed to investigate ameliorates effect of combined vitamins C and E able to against depot-medroxyprogesterone acetate- (DMPA-) induced ovarian oxidative stress in rat. Twenty-five female Wistar rats were divided into the following groups (n = 5 rats each): control (untreated) (C); depot-medroxyprogesterone acetate (DMPA); DMPA plus green vitamin C (at dose of 0.2 mg/gram; 0.4 mg/gram; 0.8 mg/gram) and vitamin E (0.04 IU/gram). The treatment with combined vitamins C and E was performed for four weeks. Analysis of malondialdehyde (MDA) level as a marker of oxidative stress was done colorimetrically. Analysis of SOD level was done by enzyme linked immunosorbent assay (ELISA) technically. This increase in ovarium MDA was significantly (P < 0.05) attenuated by medium dose treatments of combined vitamins C and E. DMPA insignificantly decreased SOD levels compared to the untreated group. This decrease in ovarian SOD level was significantly attenuated by all doses of the combined vitamins C and E. In conclusion, DMPA induces ovarian oxidative stress. Combined vitamins C and E prohibit the increase in ovarian lipid peroxidation, at least in part by modulating of superoxide dismutase. Therefore, this may provide an antioxidant therapy for attenuating the ovarian toxicity found in the DMPA therapy.

Estrogen inhibits lipid peroxidation after hypoxic-ischemic brain damage in neonatal rats

Sprague-Dawley neonatal rats within 7 days after birth were used in this study. The left common carotid artery was occluded and rats were housed in an 8% O2 environment for 2 hours to establish a hypoxic-ischemic brain damage model. 17β-estradiol (1 × 10(-5) M) was injected into the rat abdominal cavity after the model was successfully established. The left hemisphere was obtained at 12, 24, 48, 72 hours after operation. Results showed that malondialdehyde content in the left brain of neonatal rats gradually increased as modeling time prolonged, while malondialdehyde content of 17β-estrodial-treated rats significantly declined by 24 hours, reached lowest levels at 48 hours, and then peaked at 72 hours after injury. Nicotinamide-adenine dinucleotide phosphate histochemical staining showed the nitric oxide synthase-positive cells and fibers dyed blue/violet and were mainly distributed in the cortex, hippocampus and medial septal nuclei. The number of nitric oxide synthase-positive cells peaked at 48 hours and significantly decreased after 17β-estrodial treatment. Our experimental findings indicate that estrogen plays a protective role following hypoxic-ischemic brain damage by alleviating lipid peroxidation through reducing the expression of nitric oxide synthase and the content of malondialdehyde.

Organic extract contaminants from drinking water activate Nrf2-mediated antioxidant response in a human cell line

Traditional risk assessment methods face challenges in estimating risks from drinking waters that contain low-levels of large numbers of contaminants. Here, we evaluate the toxicity of organic contaminant (OC) extracts from drinking water by examining activation of nuclear factor E2-related factor 2 (Nrf2)-mediated antioxidant response. In HepG2 cells, the Nrf2-mediated antioxidant response-measured as Nrf2 protein accumulation, expression of antioxidant response element (ARE)-regulated genes and ARE-luciferase reporter gene assays were activated by OC extracts from drinking water sources that detected 25 compounds in 9 classification groups. Individual OCs induced oxidative stress at concentrations much higher than their environmental levels; however, mixtures of contaminants induced oxidative stress response at only 8 times the environmental levels. Additionally, a synthetic OC mixture prepared based on the contamination profiling of drinking water induced ARE activity to the same extent as the real-world mixture, reinforcing our conclusion that these mixture exposures produce responses relevant for human exposure situations. Our study tested the possibility of assessing toxicity of OCs of drinking water using a specific ARE-pathway measurement. This approach should be broadly useful in assisting risk assessment of mixed environmental exposure.

Intrahypothalamic estradiol regulates glucose metabolism via the sympathetic nervous system in female rats

Long-term reduced hypothalamic estrogen signaling leads to increased food intake and decreased locomotor activity and energy expenditure, and ultimately results in obesity and insulin resistance. In the current study, we aimed to determine the acute obesity-independent effects of hypothalamic estrogen signaling on glucose metabolism. We studied endogenous glucose production (EGP) and insulin sensitivity during selective modulation of systemic or intrahypothalamic estradiol (E2) signaling in rats 1 week after ovariectomy (OVX). OVX caused a 17% decrease in plasma glucose, which was completely restored by systemic E2. Likewise, the administration of E2 by microdialysis, either in the hypothalamic paraventricular nucleus (PVN) or in the ventromedial nucleus (VMH), restored plasma glucose. The infusion of an E2 antagonist via reverse microdialysis into the PVN or VMH attenuated the effect of systemic E2 on plasma glucose. Furthermore, E2 administration in the VMH, but not in the PVN, increased EGP and induced hepatic insulin resistance. E2 administration in both the PVN and the VMH resulted in peripheral insulin resistance. Finally, sympathetic, but not parasympathetic, hepatic denervation blunted the effect of E2 in the VMH on both EGP and hepatic insulin sensitivity. In conclusion, intrahypothalamic estrogen regulates peripheral and hepatic insulin sensitivity via sympathetic signaling to the liver.

17β-Estradiol and vitamin E modulates oxidative stress-induced kidney toxicity in diabetic ovariectomized rat

The aim of this study was to investigate the effects of vitamin E (alpha-tocopherol) and 17β-estradiol (E(2)) supplementation on malondialdehyde (MDA), glutathione (GSH), vitamin A, beta carotene, selenium-dependent glutathione peroxidase (GSH-Px), zinc-dependent superoxide dismutase (SOD), and copper/zinc-dependent catalase (CAT) values in the kidney of ovariectomized (OVX) diabetic rats. Forty-two female rats were randomly divided into seven equal groups as follows: group I, control; group II, OVX; group III, OVX+E(2); group IV, OVX+E(2)+alpha-tocopherol; group V, OVX+diabetic; group VI, OVX+diabetic+E(2); and group VII, OVX+diabetic+E(2)+alpha-tocopherol. E(2) (40 μg kg(-1)/day) and alpha-tocopherol (100 μg kg(-1)/day) were given. Bilateral ovariectomy was performed in all groups except group I. After 4 weeks, antioxidant and MDA levels in the kidney for all groups were analyzed. GSH-Px, CAT, SOD, GSH levels, vitamin A, and beta carotene levels were decreased in OVX group compared to those in the control group but MDA level was elevated via ovariectomy. However, E(2) and E(2)+alpha-tocopherol supplementations in OVX group was associated with an increase in the GSH-Px, GSH, CAT and Zn-SOD values, vitamin A, and beta carotene levels but a decrease in MDA levels in kidney. The MDA levels in the kidney of diabetic OVX rats were found higher than those in the control and OVX groups. However, GSH, GSH-Px, CAT, SOD, vitamin A, and beta carotene levels in kidney were lower in OVX diabetic rats. On the other hand, E(2) and E(2)+alpha-tocopherol supplementations to OVX diabetic rats have caused an increase in GSH-Px, CAT and SOD, GSH, vitamin A, and beta carotene levels but a decrease in MDA levels. In conclusion, the E(2) and E(2)+alpha-tocopherol supplementations to diabetic OVX and OVX rats may strengthen the antioxidant defense system by reducing lipid peroxidation, and therefore they may play a role in preventing renal disorders.

Estradiol modulates membrane-linked ATPases, antioxidant enzymes, membrane fluidity, lipid peroxidation, and lipofuscin in aged rat liver

Free radical production and oxidative stress are known to increase in liver during aging, and may contribute to the oxidative damage. These changes increase during menopausal condition in females when the level of estradiol is decreased. The objective of this study was to observe the changes in activities of membrane linked ATPases (Na⁺K⁺ ATPase, Ca²⁺ ATPase), antioxidant enzymes (superoxide dismutase, glutathione-S-transferase), lipid peroxidation levels, lipofuscin content and membrane fluidity occurring in livers of female rats of 3, 12 and 24 months age groups, and to see whether these changes are restored to 3 months control levels rats after exogenous administration of 17-β-estradiol (E2). The aged rats (12 and 24 months) were given subcutaneous injection of E2 (0.1 μg/g body weight) daily for one month. The results obtained in the present work revealed that normal aging was associated with significant decrease in the activities of membrane linked ATPases, antioxidant enzymes, membrane fluidity and an increase in lipid peroxidation and lipofuscin content in livers of aging female rats. The present study showed that E2 treatment reversed the changes to normal levels. E2 treatment may be beneficial in preventing some of the age related changes in the liver by increasing antioxidant defenses.

Effects of 17β-estradiol and antioxidant administration on oxidative stress and insulin resistance in ovariectomized rats

The prevalence of insulin resistance syndrome increases during menopause with the overproduction of reactive oxygen species and impairment of the free radical scavenger function. Therefore, we investigated the effects of 17β-estradiol (E2) and vitamin E, as an antioxidant, on lipid peroxidation and antioxidant levels in the brain cortex and liver of ovariectomized rats as well as on insulin resistance in those rats. Forty female Sprague–Dawley rats, 3 months of age and weighing 231.5 ± 9.4 g, were divided into 4 groups: sham, ovariectomized (OVX), OVX treated with E2 (40 µg/kg subcutaneously), and OVX treated with E2 and vitamin E (100 mg/kg intraperitoneally). The 4 groups received the appropriate treatment every day for 8 weeks. Levels of glutathione, glutathione peroxidase, superoxide dismutase , catalase, and malondialdehyde in the brain cortex and liver of ovariectomized rats were measured. Also, fasting plasma insulin, glucose, and homeostatis model assessment of insulin resistance (HOMA-IR) were determined. Malondialdehyde increased and antioxidants (glutathione, glutathione peroxidase, catalase, superoxide dismutase) decreased in the brain cortex and liver of OVX rats. Also, fasting glucose, insulin, and HOMA-IR increased in OVX rats. E2 and E2 plus vitamin E decreased malondialdehyde and increased antioxidants in the brain cortex and liver of OVX rats. Moreover, they decreased fasting glucose, insulin, and HOMA-IR in ovariectomized rats. This study demonstrates that E2 and E2 plus vitamin E supplementation to OVX rats may improve insulin resistance, strengthen the antioxidant system, and reduce lipid peroxidation.

Effects of 17β-estradiol and vitamin E treatments on blood trace element and antioxidant enzyme levels in ovariectomized rats

We investigated the effect of 17β-estradiol (E(2)) alone and separately vitamin E treatment on trace element status of rats following an ovariectomic operation. Forty rats were equally divided into four groups: Group 1, control, non-ovariectomized rats; Group 2, (OVX) rats, ovariectomized under general anesthesia; Group 3, (OVX+E(2)) rats, the group received a 40 µg kg(-1) subcutan dose of E(2) per day after ovariectomy; and Group 4, (OVX + E(2) + vitamin E) rats, received the same E(2) treatment, but with an additional 100 mg kg(-1) intraperitoneal dose of vitamin E per day after ovariectomy. At the end of the 30-day experiment, the rats were sacrificed and their blood was collected for the measurement of zinc, copper, iron, phosphorus, selenium, magnesium, calcium, manganese, and chromium; copper-zinc superoxide dismutase (SOD); manganese-superoxide dismutase (Mn-SOD); glutathione peroxidase (Se-GSH-Px); and catalase (CAT). The levels of zinc, copper, iron, phosphorus, selenium, calcium, chromium, and manganese and activities of SOD, Mn-SOD, Se-GSH-Px, and CAT were lower in the OVX than in the control group, but magnesium level was unaffected. However, zinc, copper, iron, phosphorus, selenium, calcium, chromium, and manganese levels and SOD, Mn-SOD, Se-GSH-Px, and CAT activities were higher under separate E(2) and E(2) + vitamin E treatments. The level of magnesium in the treated-OVX groups was not different than in the OVX group. In conclusion, E(2) treatment has an ameliorating effect on the trace element status in OVX, and this effect may be enhanced with the addition of vitamin E.