Long-term melatonin treatment reduces ovarian mass and enhances tissue antioxidant defenses during ovulation in the rat

Melatonin regulates the reproductive cycle, energy metabolism and may also act as a potential antioxidant indoleamine. The present study was undertaken to investigate whether long-term melatonin treatment can induce reproductive alterations and if it can protect ovarian tissue against lipid peroxidation during ovulation. Twenty-four adult female Wistar rats, 60 days old (± 250-260 g), were randomly divided into two equal groups. The control group received 0.3 mL 0.9 percent NaCl + 0.04 mL 95 percent ethanol as vehicle, and the melatonin-treated group received vehicle + melatonin (100 µg·100 g body weight-1·day-1) both intraperitoneally daily for 60 days. All animals were killed by decapitation during the morning estrus at 4:00 am. Body weight gain and body mass index were reduced by melatonin after 10 days of treatment (P < 0.05). Also, a marked loss of appetite was observed with a fall in food intake, energy intake (melatonin 51.41 ± 1.28 vs control 57.35 ± 1.34 kcal/day) and glucose levels (melatonin 80.3 ± 4.49 vs control 103.5 ± 5.47 mg/dL) towards the end of treatment. Melatonin itself and changes in energy balance promoted reductions in ovarian mass (20.2 percent) and estrous cycle remained extensive (26.7 percent), arresting at diestrus. Regarding the oxidative profile, lipid hydroperoxide levels decreased after melatonin treatment (6.9 percent) and total antioxidant substances were enhanced within the ovaries (23.9 percent). Additionally, melatonin increased superoxide dismutase (21.3 percent), catalase (23.6 percent) and glutathione-reductase (14.8 percent) activities and the reducing power (10.2 percent GSH/GSSG ratio). We suggest that melatonin alters ovarian mass and estrous cyclicity and protects the ovaries by increasing superoxide dismutase, catalase and glutathione-reductase activities.

Effect of unsaturated fatty acids on myocardial performance, metabolism and morphology

Diets rich in saturated fatty acids are one of the most important causes of atherosclerosis in men, and have been replaced with diets rich in unsaturated fatty acids (UFA) for the prevention of this disorder. However, the effect of UFA on myocardial performance, metabolism and morphology has not been completely characterized. The objective of the present investigation was to evaluate the effects of a UFA-rich diet on cardiac muscle function, oxidative stress, and morphology. Sixty-day-old male Wistar rats were fed a control (N = 8) or a UFA-rich diet (N = 8) for 60 days. Myocardial performance was studied in isolated papillary muscle by isometric and isotonic contractions under basal conditions after calcium chloride (5.2 mM) and ß-adrenergic stimulation with 1.0 æM isoproterenol. Fragments of the left ventricle free wall were used to study oxidative stress and were analyzed by light microscopy, and the myocardial ultrastructure was examined in left ventricle papillary muscle. After 60 days the UFA-rich diet did not change myocardial function. However, it caused high lipid hydroperoxide (176 ± 5 vs 158 ± 5, P < 0.0005) and low catalase (7 ± 1 vs 9 ± 1, P < 0.005) and superoxide-dismutase (18 ± 2 vs 27 ± 5, P < 0.005) levels, and discrete morphological changes in UFA-rich diet hearts such as lipid deposits and mitochondrial membrane alterations compared to control rats. These data show that a UFA-rich diet caused myocardial oxidative stress and mild structural alterations, but did not change mechanical function.

Effect of Brazilian propolis on experimental hepatotoxicity in rats

Propolis (bee glue) is one of the major hive products of bees and is rich in flavanoids, which are known for their antioxidant activities. The aim of this study was to evaluate the hepatoprotective effects of the ethanolic extract of propolis (EEP) against experimental carbon tetrachloride (CCl4)-induced liver toxicity in rats by means of biochemical indices. The animals were divided into 4 groups: GI= received mineral oil; GII= CCl4 (4mL/kg; i.p., single dose) treated; GIII= CCl4 (4mL/kg; i.p., single dose) treatment followed by ethanolic extract propolis (100mg/kg) for gavage from the species Tetragonisca angustula, daily for 3 days and GIV= CCl4 (4mL/kg; i.p., single dose) treatment followed by ethanolic extract of propolis (100mg/kg) for gavage from the species Nannotrigonea testaceicornes , daily, for 3 days. The serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), cholesterol and tricylglycerols were estimated after 3 days. CCl4 caused a maximum increase (p,0,01) above biochemical parameters. As compared to CCl4 group (GII) the EEP (GIII and GIV) showed reduction in cholesterol, triacylglycerol, ALT, AST and alkaline phosphatase activity in the serum. In conclusion, these data indicate that EEP improved the dyslipidaemia, moreover, significantly attenuated increases in serum ALT and AST activities in rats with liver damage induced by carbon tetrachloride

Seasonal effect of brazilian propolis on seric biochemical variables

Propolis has been the subject of recent scientific investigation due to its bilogical properties, such as antibiotic, antiinflammatory, anesthetic, healing, immunomodulatory, antioxidant, and carcinostatic. The purpose of this study was to analyze the biochemical profile of propolis-treated rats to observe whether propolis might lead to side effects after administration. Evaluation of total protein, glucose, urea, creatinine, triglycerides, cholesterol, and HDL-cholesterol concentrations and determination of aminotransferases (AST and ALT) and lactic dehydrogenase (LDH) in propolis-treated rat serum were performed. The seasonal effect on propolis activity was also analysed, considering the biochemical variables evaluated. The lack of clinically important changes in seric biochemical variables is probably because propolis showed no biological side effects under these conditions. A possible seasonal effect on the biochemical determinations was not observed.

Serum biochemical determinations of propolis-treated rats

Ethanolic extracts of the bee glue, a resinous substance collected by honeybees called propolis, have been widely used in folk medicine since ancient times. Antibacterial, antifungal and thus antiseptic properties may represent the basis for the historical and present use of these extracts in dermatology, against inflammatory conditions and common colds. This work was carried out in order to verify possible biochemical alterations in some seric parameters of propolis-treated rats. It was shown that propolis possesses an antioxidant property and its administration did not affect either amylase and alanine transaminase activities or total protein concentration.

High dietary carbohydrate and pancreatic lesion

The ability of high dietary carbohydrate to induce acute pancreatitis was investigated in groups of 16, 21-day and 15-month old rats fed different carbohydrate diets for 30 days. Significantly increased levels of serum amylase (2-fold), phospholipids (50 per cent ), phosphorus (2-fold), and lipoperoxides (8-fold) were observed in 15-month old rats fed a high-carbohydrate diet, compared to rats fed a diet with normal carbohydrate levels, indicating peroxidation of membrane lipids which caused final cell death and pancreatic lesion. Serum Cu-Zn superoxide dismutase activity was not altered. Daily administration of bovine Cu-Zn superoxide dismutase conjugated with polyethylene glycol prevented the serum level alterations and pancreatic lesions, indicating that the superoxide radical has a role in dietary carbohydrate-induced acute pancreatitis. No biochemical changes were observed in rats in which treatment was initiated on the 21st day of life indicating that this is an age-related lesion

Nickel chloride effects on erythrocyte generation of superoxide radical

The superoxide anion (O2) is an extremely potent free radical which is produced during the metabolism of aerobic linving cells. (O2) may be involved in lipid peroxidation reactions which occur in a variety of systems. Cu-Zn speroxide dimutase, a metalloprotein, catalyzes the dismutation of the superoxide free radical and protects cells aginst superoxide damage. The ability of NiCl2 to prevent lysis of erythrocytes was tested in rats. NiCl2 administered by intratracheal rouyte prevented hemolysis and decreased total lipids, phospholipids and bilirubin in serum. The protective effect of NiCl2 was linked to an increase in the erytrocyte activity of superoxide dismutase