Sexual dimorphism of liver endoplasmic reticulum stress susceptibility in prepubertal rats and the effect of sex steroid supplementation.

NEW FINDINGS: What is the central question of this study? Is there sexual dimorphism in the occurrence of hepatic endoplasmic reticulum stress? What is the main finding and its importance? The transition from prepubertal to the adult age is associated with an increase in the unfolded protein response markers in the liver of male rats, which is probably due to an increase in serum testosterone levels. ABSTRACT: Male rodents present a higher predisposition to obesity and insulin resistance than females. These disorders have been associated with endoplasmic reticulum (ER) stress. To investigate a possible sexual dimorphism in the hepatic occurrence of ER stress, we evaluated the expression of ER stress markers in the livers of male and female rats in two phases of sexual development. In the first experimental model, male and female prepubertal and adult Wistar rats were used. Adult males presented higher body mass and greater mass of the adipose tissue and liver than adult females. Prepubertal animals presented no differences in these parameters between males and females. Despite this finding, the hepatic expression levels of Bip, Ire1α and Xbp1s mRNA were lower in prepubertal males than in females, while in adult animals, they did not differ between sexes. In the second experimental model, we anticipated the sexually mature phase by daily injections of testosterone propionate for 10 days in prepubertal males or by daily injections of oestradiol benzoate for 7 days in prepubertal females. Oestradiol administration in prepubertal females did not change any of the parameters evaluated. Testosterone administration to prepubertal males led to a higher body mass and greater expression of Bip, Ire1α, Atf4 and Xbp1s in the liver. These findings suggest that the increased ER stress predisposition observed in males during puberty is due to an increase in testosterone levels, indicating that ER stress is sexually dimorphic before puberty due to the lack of testosterone in males.

Multiple mechanistic action of Rosmarinus officinalis L. extract against ethanol effects in an acute model of intestinal damage.

The high levels of oxidative stress and inflammation can be present in the etiology of degenerative intestinal pathologies associated with ethanol ingestion. The Rosmarinus officinalis L. has exhibited several physiological and medicinal activities. In this investigation, we intended to clarify, for the first time, the antioxidant and anti-inflammatory effects of ethanolic extract of Rosmarinus officinalis L. (eeRo) against an acute damage induced by ethanol, specifically in the small intestine of rats. The rats were treated three times, at every 24 h, with eeRo at 500-1000 mg/kg or vehicle, oral gavage. All groups got a single dose of ethanol (2 ml/kg), oral gavage, after 36 h of fasting and 1 h after the last dose of eeRo or vehicle administration. We performed the mensuration of oxidative stress profile in lipid peroxidation in serum and intestine; Na+/K+ ATPase, catalase, and superoxide dismutase activities assays only in intestine; and anti-inflammatory evidences of eeRo in myeloperoxidase activity assay only in the intestine. The eeRo was able to protect the animals against the lipid peroxidation in serum and intestine. It prevented the reduction in Na+/K+ ATPase and catalase levels induced by ethanol in the intestine. In addition, eeRo increased the superoxide dismutase activity when compared to control and protected the intestine against elevations in myeloperoxidase activity caused by ethanol. Our results suggested that eeRo exerted a significant intestinal protective effect by antioxidant and anti-inflammatory mechanisms. Thus, the eeRo represented a promising agent against intestinal lesions induced by ethanol.

4-Phenyl butyric acid increases particulate hexokinase activity and protects against ROS injury in L6 myotubes.

Hexokinase (HK) is the first enzyme in the glycolytic pathway and is responsible for glucose phosphorylation and fixation into the cell. HK (HK-II) is expressed in skeletal muscle and can be found in the cytosol or bound mitochondria, where it can protect cells against insults such as oxidative stress. 4-Phenyl butyric acid (4-PBA) is a chemical chaperone that inhibits endoplasmic reticulum stress and contributes to the restoring of glucose homeostasis. AIMS: Here, we decided to investigate whether HK activity and its interaction with mitochondria could be a target of 4-PBA action. MAIN METHODS: L6 myotubes were treated with 1mM 4-PBA for 24, 48 or 72h. We evaluated HK activity, glucose and oxygen consumption, gene and protein expression. KEY FINDINGS: We found that L6 myotubes treated with 4-PBA presented more HK activity in the particulate fraction, increased glucose consumption and augmented Glut4, Hk2 and Vdac1 mRNA expression. Moreover, 4-PBA prevented the deleterious effect of antimycin-A on HK particulate activity. SIGNIFICANCE: Together, these results suggest a new role of 4-PBA in glucose metabolism that includes HK as a potential target of beneficial effect of 4-PBA.

Neuroprotective effect of diphenyl diselenide in a experimental stroke model: maintenance of redox system in mitochondria of brain regions.

Acute stroke is a major risk for morbidity and mortality in aging population. Mitochondrion has been the focus of a wide stroke-related research. This study investigated if treatment or pre-treatment with diphenyl diselenide (PhSe)2 can prevent mitochondrial damage in cerebral structures of rats induced by an ischemia and reperfusion (I/R) model. Adult male Wistar rats were assigned into five experimental groups: sham operation, ischemia/reperfusion, pre-treated + I/R, treated + I/R, and Sham + (PhSe)2. Neurological score showed the damage caused by I/R, which was partially prevented by (PhSe)2. Moreover, mitochondria of hippocampus and cortex were impaired by I/R through an increase of reactive oxygen species production, mitochondrial membrane potential (ΔΨm) and electrons flow alteration, activity of complex I deregulation as well as mitochondrial swelling. However, the ischemic damage did not induce an increase in pro-apoptotic proteins expression, but demonstrated an enhanced expression of Hsp70. The mitochondrial redox state was also altered (GSH/GSSG ratio, MnSOD, and GPx activities). Our results revealed that all treatments with (PhSe)2 significantly reduced the mitochondrial damage induced by I/R. These findings suggest that neuroprotective properties of (PhSe)2 may be attributed to the maintenance of mitochondrial redox balance.

Protective action of ethanolic extract of Rosmarinus officinalis L. in gastric ulcer prevention induced by ethanol in rats.

The pathology of a gastric ulcer is complex and multifactorial. Gastric ulcers affect many people around the world and its development is a result of the imbalance between aggressive and protective factors in the gastric mucosa. In this study, we evaluated the ethanolic extract of Rosmarinus officinalis L. (eeRo); this plant, more commonly known as rosemary, has attracted the interest of the scientific community due to its numerous pharmacological properties and their potential therapeutic applications. Here, we tested the preventive effects of eeRo against gastric ulcer induced by 70% ethanol in male Wistar rats. In addition, we aimed to clarify the mechanism involved in the preventive action of the eeRo in gastric ulcers. Based on the analysis of markers of oxidative damage and enzymatic antioxidant defense systems, the measurement of nitrite and nitrate levels and the assessment of the inflammatory response, the eeRo exhibited significant antioxidant, vasodilator and antiinflammatory properties.

Reduction of acute hepatic damage induced by acetaminophen after treatment with diphenyl diselenide in mice.

In this study, the authors evaluated the ability of diphenyl diselenide (PhSe)(2) to reverse acute hepatic failure induced by acetaminophen (APAP) in mice. The animals received an APAP dose of 600 mg/kg intraperitoneally (i.p.), and then 1 hour later, they received 15.6 mg/kg i.p. of (PhSe)(2). Three hours after (PhSe)(2) administration, the animals were sacrificed and blood and liver samples were collected for analysis. The serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were measured. The levels of reduced glutathione (GSH) and oxidized glutathione (GSSG), thiobarbituric acid-reactive substances (TBARS), 2',7'-dichlorofluorescein (DFC), catalase activity (CAT), and myeloperoxidase (MPO) activity were determined in the liver. A methyl-tetrazolium reduction (MTT) assay was also performed on the liver. Histopathological studies were conducted in all groups. Exposure of animals to APAP induced oxidative stress, increased lipid peroxidation (LPO), and the generation of reactive species, reduced the levels of GSH, and caused an increase in the MPO activity. Treatment with (PhSe)(2) reduced LPO and the formation of reactive species and inhibited the processes of inflammation, reducing the hepatic damage induced by APAP. The results of this study show that (PhSe)(2) is a promising therapeutic option for the treatment of acute hepatic failure.

Acute brain damage induced by acetaminophen in mice: effect of diphenyl diselenide on oxidative stress and mitochondrial dysfunction.

Organoselenium compounds exhibit antioxidant activity, as well as a variety of biological activities, with potential pharmacological and therapeutic applications. The aim of this study was to investigate the effect of diphenyl diselenide (PhSe)(2) in reversing oxidative brain damage and mitochondrial dysfunction caused by administration of acetaminophen (APAP) in mice. Mice received a toxic dose of APAP, followed by a dose of (PhSe)(2) 1 h later. Four hours after the administration of APAP, plasma was withdrawn from the mice and used for biochemical assays of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) as markers of hepatotoxicity. Brain homogenate was examined to determine oxidative stress. Isolated brain mitochondria were examined to quantify mitochondrial transmembrane's electrical potential and mitochondrial swelling and to estimate reactive oxygen species (ROS) production. APAP administration caused an increase in plasma ALT and AST activities. APAP administration also caused a significant increase in the levels of thiobarbituric acid reactive substances (TBARS) and dichlorofluorescein oxidation in brain homogenate. Similarly, mitochondrial swelling and ROS production increased after APAP administration. APAP treatment also caused a decrease in Na(+), K(+)- ATPase activity and in mitochondrial membrane potential. These alterations observed in the brain of APAP-treated mice were restored by (PhSe)(2). Glutathione levels were decreased by APAP, but (PhSe)(2) did not reverse this change. Treatment with (PhSe)(2) after APAP administration can reverse the neurotoxicity caused by a single toxic dose of APAP. The neuroprotective effect of (PhSe)(2) is likely associated with its antioxidant properties.

Clomipramine treatment and repeated restraint stress alter parameters of oxidative stress in brain regions of male rats.

This study aimed to compare the effects of repeated restraint stress alone and the combination with clomipramine treatment on parameters of oxidative stress in cerebral cortex, striatum and hippocampus of male rats. Animals were divided into control and repeated restraint stress, and subdivided into treated or not with clomipramine. After 40 days of stress and 27 days of clomipramine treatment with 30 mg/kg, the repeated restraint stress alone reduced levels of Na(+), K(+)-ATPase in all tissues studied. The combination of repeated restraint stress and clomipramine increased the lipid peroxidation, free radicals and CAT activity as well as decreased levels of NP-SH in the tissues studied. However, Na(+), K(+)-ATPase level decreased in striatum and cerebral cortex and the SOD activity increased in hippocampus and striatum. Results indicated that clomipramine may have deleterious effects on the central nervous system especially when associated with repeated restraint stress and chronically administered in non therapeutic levels.