Uncoupling the relationship between fatty acids and longevity

Dietary Fatty Acids and Temperature Modulate Mitochondrial Function and Longevity in Drosophila

Fluctuations in temperature and resource availability are conditions many organisms contend with in nature. Specific dietary nutrients such as fatty acids play an essential role in reproduction, cold adaptation, and metabolism in a variety of organisms. The present study characterizes how temperature and diet interact to modulate Drosophila physiology and life span. Flies were raised on media containing specific saturated, monounsaturated, or polyunsaturated fatty acids supplements at low concentrations and were placed in varied thermal environments. We found that dietary long-chain polyunsaturated fatty acids improve chill coma recovery and modulate mitochondrial function. Additionally, monounsaturated and polyunsaturated fatty acid food supplements were detrimental to life span regardless of temperature, and antioxidants were able to partially rescue this effect. This study provides insight into environmental modulation of Drosophila physiology and life span.

Potential role of dietary lipids in the prophylaxis of some clinical conditions

An imbalance of dietary lipids may potentially have a significant role in the pathobiology of some chronic diseases. Public health dietary fat recommendations have emphasized that low saturated fat, high monounsaturated fat, and high polyunsaturated fat with a lower ω-6 to ω-3 fatty acid ratio intake are necessary for normal health. However, such universal recommendations are likely to be hazardous, since the outcome of recommended lipid intake may depend on the consumption of other important dietary constituents that have an important role in the metabolism of lipids. In addition, consumption of fatty acids as per the individually tailored specific requirements in the context of other nutritional factors may have the potential to stabilize hormones, mood and sleep, and minimize adverse events. In support of this proposal, we review various factors that influence fatty acid metabolism, which need to be taken into consideration for appropriate utilization and consequently prevention of various diseases.

Accelerated protein evolution analysis reveals genes and pathways associated with the evolution of mammalian longevity

The genetic basis of the large species differences in longevity and aging remains a mystery. Thanks to recent large-scale genome sequencing efforts, the genomes of multiple species have been sequenced and can be used for cross-species comparisons to study species divergence in longevity. By analyzing proteins under accelerated evolution in several mammalian lineages where maximum lifespan increased, we identified genes and processes that are candidate targets of selection when longevity evolves. We identified several proteins with longevity-specific selection patterns, including COL3A1 that has previously been related to aging and proteins related to DNA damage repair and response such as DDB1 and CAPNS1. Moreover, we found that processes such as lipid metabolism and cholesterol catabolism show such patterns of selection and suggest a link between the evolution of lipid metabolism, cholesterol catabolism, and the evolution of longevity. Lastly, we found evidence that the proteasome-ubiquitin system is under selection specific to lineages where longevity increased and suggest that its selection had a role in the evolution of longevity. These results provide evidence that natural selection acts on species when longevity evolves, give insights into adaptive genetic changes associated with the evolution of longevity in mammals, and provide evidence that at least some repair systems are selected for when longevity increases.

Effects of moderate electrical stimulation on reactive species production by primary rat skeletal muscle cells: cross talk between superoxide and nitric oxide production

The effects of a moderate electrical stimulation on superoxide and nitric oxide production by primary cultured skeletal muscle cells were evaluated. The involvement of the main sites of these reactive species production and the relationship between superoxide and nitric oxide production were also examined. Production of superoxide was evaluated by cytochrome c reduction and dihydroethidium oxidation assays. Electrical stimulation increased superoxide production after 1 h incubation. A xanthine oxidase inhibitor caused a partial decrease of superoxide generation and a significant amount of mitochondria-derived superoxide was also observed. Nitric oxide production was assessed by nitrite measurement and by using 4,5-diaminofluorescein diacetate (DAF-2-DA) assay. Using both methods an increased production of nitric oxide was obtained after electrical stimulation, which was also able to induce an increase of iNOS content and NF-κB activation. The participation of superoxide in nitric oxide production was investigated by incubating cells with DAF-2-DA in the presence or absence of electrical stimulation, a superoxide generator system (xanthine-xanthine oxidase), a mixture of NOS inhibitors and SOD-PEG. Our data show that the induction of muscle contraction by a moderate electrical stimulation protocol led to an increased nitric oxide production that can be controlled by superoxide generation. The cross talk between these reactive species likely plays a role in exercise-induced maintenance and adaptation by regulating muscular glucose metabolism, force of contraction, fatigue, and antioxidant systems activities.

Reduced expression of uncoupling protein 2 in adipose tissue in patients with hypothyroidism

CONTEXT

Thyroid disease is associated with major metabolic changes, comprising changes in lipid metabolism. Thyroid hormones have previously been shown to increase UCP2 mRNA expression in fat biopsies from hyperthyroid patients, but data from hypothyroid patients have so far not been reported.

PATIENTS AND METHODS

Eleven hypothyroid patients were studied before and after l-T(4) replacement, and 10 healthy controls matched for sex, age, and body mass index were studied once. Subcutaneous fat biopsies were performed, and UCP2 mRNA expression was measured in these biopsies. Patients also underwent indirect calorimetry and blood sampling.

RESULTS

Patients were profoundly hypothyroid at study entry with significantly increased TSH levels (149.9 + or - 60.4 mU/liter). UCP2 mRNA expression was reduced in the hypothyroid state as compared with the euthyroid state (0.0081 + or - 0.0028 vs. 0.0420 + or - 0.0076, P < 0.01). Using pooled data from hypothyroid patients and control subjects, we found positive correlations between lipid oxidation rates and adipose tissue UCP2 expression (r = 0.63; P < 0.004), basal free fatty acid levels and UCP2 expression (r = 0.51; P < 0.03), and T(3) levels and UCP2 (r = 0.69; P < 0.001).

CONCLUSION

Our study demonstrates that hypothyroidism is associated with a profound decrease in UCP2 mRNA expression. It supports the notion that UCP2 is a determinant of fat oxidation pathways and may be involved in the changes seen in the metabolic pathways in thyroid disease.

Palmitate increases superoxide production through mitochondrial electron transport chain and NADPH oxidase activity in skeletal muscle cells

The effect of unbound palmitic acid (PA) at plasma physiological concentration range on reactive oxygen species (ROS) production by cultured rat skeletal muscle cells was investigated. The participation of the main sites of ROS production was also examined. Production of ROS was evaluated by cytochrome c reduction and dihydroethidium oxidation assays. PA increased ROS production after 1 h incubation. A xanthine oxidase inhibitor did not change PA-induced ROS production. However, the treatment with a mitochondrial uncoupler and mitochondrial complex III inhibitor decreased superoxide production induced by PA. The importance of mitochondria was also evaluated in 1 h incubated rat soleus and extensor digitorum longus (EDL) muscles. Soleus muscle, which has a greater number of mitochondria than EDL, showed a higher superoxide production induced by PA. These results indicate that mitochondrial electron transport chain is an important contributor for superoxide formation induced by PA in skeletal muscle. Results obtained with etomoxir and bromopalmitate treatment indicate that PA has to be oxidized to raise ROS production. A partial inhibition of superoxide formation induced by PA was observed by treatment with diphenylene iodonium, an inhibitor of NADPH oxidase. The participation of this enzyme complex was confirmed through an increase of p47(phox) phosphorylation after treatment with PA.