High-fat diet intake induces depressive-like behavior in ovariectomized rats.

This study tested the effects of ovariectomy, allied or not to high-fat feeding and estradiol replacement, on hormonal, metabolic and behavioral parameters, to explore the connection of obesity and depression after menopause. Wistar rats were either ovariectomized or sham-operated and fed with either standard chow or lard-enriched diet for twelve weeks. Sub-groups of ovariectomized rats received estradiol replacement. Depressive-like behaviors were assessed by the forced swim test and locomotor activity was assessed by the elevated plus maze test. Ovariectomy alone increased body weight gain and feed efficiency and induced hyperleptinemia and glucose intolerance while it increased caloric intake and body adiposity only marginally. High-fat intake alone induced obesity and, in combination with ovariectomy, accentuated the ovariectomy-induced alterations. Estradiol replacement attenuated the hormonal alterations only in chow-fed rats. Ovariectomy combined with high-fat intake induced depressive-like behaviors, which were marginally attenuated by estradiol. Depressive-like behaviors were associated with metabolic and body composition parameters and with estrogen status. The data indicate that the vulnerability to develop depression after menopause is influenced by high-fat intake. It is suggested that weight management is a crucial issue in postmenopausal women, probably having a beneficial role in preventing the appearance of mental health problems.

A diet including xanthan gum triggers a pro-inflammatory response in Wistar rats inoculated with Walker 256 cells.

OBJECTIVE: The aim of this study was to evaluate the effect of adding xanthan gum to the diet of rats on the production of cytokines and pro-inflammatory factors and on tumor development in rats inoculated with Walker 256 tumor cells. METHODS: Fifty-six rats were divided into 4 groups: control diet (C), control diet with tumor (TC), xanthan gum diet (XG), xanthan gum diet with tumor (TXG). RESULTS: The ingestion of xanthan gum promotes changes in cytokine content: increasing IL-6 TNF-α and IL-10 in retroperitoneal adipose tissue compared to the control group; and increasing TNF-α in the mesenteric adipose tissue compared to the C and TXG groups. On the contrary, the addition of xanthan gum to the diet did not affect the development of Walker 256 tumors in rats. CONCLUSION: The continuous use of xanthan gum triggered a pro-inflammatory response, promoting an increase in pro-inflammatory cytokines in the adipose tissue, but it did not have an effect on the tumor development in the animals inoculated with Walker 256 tumor cells.

Ginkgo biloba Extract Modulates the Retroperitoneal Fat Depot Proteome and Reduces Oxidative Stress in Diet-Induced Obese Rats.

The rapid increase in the number of individuals with obesity, over the past four decades, is triggered by a number of complex interactions among factors. Despite the plethora of treatments available, side effects are commonly observed and, in this context, herbal medicines have been employed as an alternative form of therapy. Ginkgo biloba extract (GbE) has been described as a promising new pharmacological approach to treat obesity. In order to better comprehend the mechanisms involved with this potential effect, the present study evaluated the effects of GbE treatment on diet-induced obese rats, focusing on the proteome and the oxidative stress defense system of visceral adipose tissue. After 14 days treatment, GbE significantly modulated 25 proteins. Retroperitoneal adipose tissue of treated animals exhibited higher amounts of proteins associated with adipogenesis (decorin), carbon metabolism and mitochondrial function (citrate synthase), and a concomitant reduction in adipocyte hypertrophy. In parallel, GbE down-regulated proteins involved in oxidative stress (peroxiredoxin) and the inflammatory response (complement C3, mast cell protease 1, and Ig gamma-2B chain C region). Moreover, also related to oxidative stress defense, GbE stimulated catalase activity, reduced malondialdehyde levels (lipid peroxidation indicator), and increased lactoylglutathione lyase levels. It was concluded that GbE acts as an antioxidant agent, and improved the proteome profile and oxidative stress response in the adipose tissue of diet-induced obese rats.

Maternal consumption of green tea extract during pregnancy and lactation alters offspring's metabolism in rats.

INTRODUCTION: Green tea extract has anti-inflammatory and antioxidant effects which improve dyslipidemia and decrease adipose tissue depots associated with hyperlipidic diet consumption. OBJECTIVE: To evaluate the effect of green tea extract consumption by rats during pregnancy and lactation on the metabolism of their offspring that received control or high-fat diet with water during 10 weeks after weaning. METHODS: Wistar rats received water (W) or green tea extract diluted in water (G) (400 mg/kg body weight/day), and control diet (10 animals in W and G groups) during pregnancy and lactation. After weaning, offspring received water and a control (CW) or a high-fat diet (HW), for 10 weeks. One week before the end of treatment, oral glucose tolerance test was performed. The animals were euthanized and the samples were collected for biochemical, hormonal and antioxidant enzymes activity analyses. In addition, IL-10, TNF-α, IL-6, and IL-1ß were quantified by ELISA while p-NF-κBp50 was analyzed by Western Blotting. Repeated Measures ANOVA, followed by Tukey's test were used to find differences between data (p < 0.05). RESULTS: The consumption of high-fat diet by rats for 10 weeks after weaning promoted hyperglycemia and hyperinsulinemia, and increased fat depots. The ingestion of a high-fat diet by the offspring of mothers who consumed green tea extract during pregnancy and lactation decreased the inflammatory cytokines in adipose tissue, while the ingestion of a control diet increased the same cytokines. CONCLUSION: Our results demonstrate that prenatal consumption of green tea associated with consumption of high-fat diet by offspring after weaning prevented inflammation. However, maternal consumption of the green tea extract induced a proinflammatory status in the adipose tissue of the adult offspring that received the control diet after weaning.

New phenotypic diversity associated with the mitochondrial tRNA(SerUCN) gene mutation.

We performed detailed clinical, histopathological, biochemical, in vitro translation and molecular genetic analysis in patients from two unrelated families harbouring the tRNA(SerUCN) 7472C-insertion mutation. Proband 1 developed a progressive neurodegenerative phenotype characterised by myoclonus, epilepsy, cerebellar ataxia and progressive hearing loss. Proband 2 had a comparatively benign phenotype characterised by isolated myopathy with exercise intolerance. Both patients had the 7472C-insertion mutation in identical proportions and they exhibited a similar muscle biochemical and histopathological phenotype. However, proband 2 also had a previously unreported homoplasmic A to C transition at nucleotide position 7472 in the tRNA(SerUCN) gene. This change lengthens further the homopolymeric C run already expanded by the 7472C-insertion. These data extend the phenotypic range associated with the 7472C-insertion to include isolated skeletal myopathy, as well as a MERRF-like phenotype.

Impaired mitochondrial translation in human myoblasts harbouring the mitochondrial DNA tRNA lysine 8344 A-->G (MERRF) mutation: relationship to proportion of mutant mitochondrial DNA.

The mitochondrial DNA transfer RNA lysine A8344G mutation is commonly associated with the MERRF (myoclonus epilepsy with ragged red fibre) phenotype. The molecular pathogenesis of disease associated with this mutation is unclear. Theoretically, a mitochondrial tRNA mutation might affect transcription or translation, or both. We therefore studied these processes in cloned primary human myoblast cultures containing different proportions of mutant mtDNA. No abnormality of transcription was observed. However, there was a progressive decrease in mitochondrially encoded protein synthesis as the proportion of mutant mtDNA increased. Furthermore, there was evidence that subunits were differentially affected, based on selective reduction of cytochrome c oxidase subunits with relatively low proportions of mutant mtDNA.

Genetics and molecular pathogenesis of mitochondrial respiratory chain diseases.

Dysfunction of the mitochondrial respiratory chain has been recognised as a cause of human disease for over 30 years. Advances in the past 10 years have led to a better understanding of the genetics and molecular pathogenesis of many of these disorders. Over 100 primary defects in mitochondrial DNA (mtDNA) are now implicated in the pathogenesis of a group of disorders which are collectively known as the mitochondrial encephalomyopathies, and which most frequently involve skeletal muscle and/or the central nervous system. Although impaired oxidative phosphorylation is likely to be the final common pathway leading to the cellular dysfunction associated with such mtDNA mutations, the complex relationship between genotype and phenotype remains largely unexplained. Most of the genes which encode the respiratory chain reside in the nucleus, yet only five nuclear genes have been implicated in human respiratory chain diseases. There is evidence that respiratory chain dysfunction is present in common neurological diseases such as Parkinson's disease and Huntington's disease. The precise cause of this respiratory chain dysfunction and its relationship to the disease process are unclear. This review focuses upon respiratory chain disorders associated with primary defects in mtDNA.

MELAS: a new disease associated mitochondrial DNA mutation and evidence for further genetic heterogeneity.

OBJECTIVES: To define the molecular genetic basis of the MELAS phenotype in five patients without any known mutation of mitochondrial DNA. METHODS: Systematic automated mitochondrial DNA sequencing of all mitochondrial transfer RNA and cytochrome c oxidase genes was undertaken in five patients who had the MELAS phenotype. RESULTS: A novel heteroplasmic mitochondrial DNA mutation was identified in the transfer RNA gene for phenylalanine in one case (patient 3). This mutation was not detected in the patient's blood or in her mother's blood. No pathogenic mutations were identified in the other four patients. CONCLUSIONS: This is the first point mutation in the transfer RNA gene for phenylalanine to be associated with MELAS. The absence of mutations in the remaining four patients suggests that there is further genetic heterogeneity associated with this mitochondrial phenotype.

The mitochondrial DNA G13513A transition in ND5 is associated with a LHON/MELAS overlap syndrome and may be a frequent cause of MELAS.

We report on 4 male patients with clinical, radiological, and muscle biopsy findings typical of the mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) phenotype. Skeletal muscle mitochondrial DNA (mtDNA) analysis showed that all patients harbored a heteroplasmic G13513A mutation in the ND5 subunit gene. One of these cases (Patient 1) presented with symptoms characteristic of Leber's hereditary optic neuropathy (LHON) 2 years before the first stroke-like episode. Quantitative analysis in several postmortem tissue sections showed that the relative proportions of mutant mtDNA were generally lower than those reported with other pathogenic mtDNA mutations. Single-fiber polymerase chain reaction studies demonstrated significantly higher amounts of mutant mtDNA in ragged red fibers (RRFs) compared with non-RRFs. This study indicates that the G13513A transition is likely to be pathogenic, that it can cause an LHON/MELAS overlap syndrome, and that it may be a more frequent cause of MELAS than previously recognized.

Cytochrome c oxidase deficiency associated with the first stop-codon point mutation in human mtDNA.

We have identified the first stop-codon point mutation in mtDNA to be reported in association with human disease. A 36-year-old woman experienced episodes of encephalopathy accompanied by lactic acidemia and had exercise intolerance and proximal myopathy. Histochemical analysis showed that 90% of muscle fibers exhibited decreased or absent cytochrome c oxidase (COX) activity. Biochemical studies confirmed a severe isolated reduction in COX activity. Muscle immunocytochemistry revealed a pattern suggestive of a primary mtDNA defect in the COX-deficient fibers and was consistent with either reduced stability or impaired assembly of the holoenzyme. Sequence analysis of mtDNA identified a novel heteroplasmic G-->A point mutation at position 9952 in the patient's skeletal muscle, which was not detected in her leukocyte mtDNA or in that of 120 healthy controls or 60 additional patients with mitochondrial disease. This point mutation is located in the 3' end of the gene for subunit III of COX and is predicted to result in the loss of the last 13 amino acids of the highly conserved C-terminal region of this subunit. It was not detected in mtDNA extracted from leukocytes, skeletal muscle, or myoblasts of the patient's mother or her two sons, indicating that this mutation is not maternally transmitted. Single-fiber PCR studies provided direct evidence for an association between this point mutation and COX deficiency and indicated that the proportion of mutant mtDNA required to induce COX deficiency is lower than that reported for tRNA-gene point mutations. The findings reported here represent only the second case of isolated COX deficiency to be defined at the molecular genetic level and reveal a new mutational mechanism in mitochondrial disease.

An mtDNA mutation in the initiation codon of the cytochrome C oxidase subunit II gene results in lower levels of the protein and a mitochondrial encephalomyopathy.

A novel heteroplasmic 7587T-->C mutation in the mitochondrial genome which changes the initiation codon of the gene encoding cytochrome c oxidase subunit II (COX II), was found in a family with mitochondrial disease. This T-->C transition is predicted to change the initiating methionine to threonine. The mutation load was present at 67% in muscle from the index case and at 91% in muscle from the patient's clinically affected son. Muscle biopsy samples revealed isolated COX deficiency and mitochondrial proliferation. Single-muscle-fiber analysis revealed that the 7587C copy was at much higher load in COX-negative fibers than in COX-positive fibers. After microphotometric enzyme analysis, the mutation was shown to cause a decrease in COX activity when the mutant load was >55%-65%. In fibroblasts from one family member, which contained >95% mutated mtDNA, there was no detectable synthesis or any steady-state level of COX II. This new mutation constitutes a new mechanism by which mtDNA mutations can cause disease-defective initiation of translation.