Linkage between insulin and the free radical theory of aging

Effects of Feed Restriction on Growth Performance, Nutrient Utilisation, Biochemical Parameters, and the Caecum Microbiota and Metabolites in Rabbits

The main objective of this research was to observe the effects of feed restriction on caecum microbiota and metabolites in rabbits. Forty-eight male 8-week-old rabbits with similar body weights (1872.11 ± 180.85 g) were randomly assigned to two treatments according to completely randomized design: (1) the control group received ad libitum access to feed (AL), and (2) the treatment received 80% of the feed consumed by the control (FR). The results showed that FR did not differ (p > 0.05) for average daily weight gain or feed conversion ratio between the two groups. FR treatment led to a significant increase (p < 0.05) in acid detergent fibre apparent faecal digestibility, nitrogen digestibility and retention, and gross energy digestibility and retention. The FR treatment showed significantly (p < 0.05) lower blood triglycerides, creatinine, high-density lipoprotein cholesterol, malondialdehyde, and hydroxyl free radicals but significantly (p < 0.05) greater total antioxidant capacity and superoxide dismutase. The FR group presented greater (p < 0.05) Firmicutes and Ruminococcus abundances but a lower (p < 0.05) Akkermansiaceae abundance in the caecal content. Moreover, 222 differentiated metabolites were identified, and beta-alanine metabolism was the top enriched pathway. Collectively, FR can improve nutrient utilisation, lipid metabolism, antioxidant activity, caecum microbiota, and metabolites in rabbits.

Retarded tempo of physiological development in childhood delays the onset of the metabolic syndrome in adulthood

Using serial data from the Fels Longitudinal Study, we investigated the effects of early and late attainment of the peak height velocity (PHV) in childhood on the timing of the appearance of the metabolic syndrome later in life. We aimed to show if early attainment of PHV engenders greater risks for chronic diseases in boys than in girls. Therefore, we defined those boys and girls in sex-specific quartiles of the study population that were slowest to attain PHV as having a slow tempo of development, and those in the growth that most rapidly attained PHV as having a rapid tempo of development. Boys who experienced an early onset of PHV tended to have a higher risk for the metabolic syndrome, dyslipidemia and impaired fasting glucose than those who had late onset of PHV. Girls who had an early onset of PHV tended to develop more abdominal obesity than females who had a late onset of PHV.

Effect of estrogens on base excision repair in brain and liver mitochondria of aged female rats

Changes in the endocrine system have been suggested to act as signaling factors in the regulation of age-related events. Among the different hormones that have been linked to the aging process, estrogens have been widely investigated. They have been associated with inflammatory and oxidative processes and several investigations have established a relationship between the protective effects of estrogens and the mitochondrial function. Mitochondrial DNA is subjected to continuous oxidative attack by free radicals, and the base excision repair (BER) pathway is the main DNA repair route present in mitochondria. We have investigated the effect of estrogen levels on some of the key enzymes of BER in brain and liver mitochondria. In both tissues, depletion of estrogens led to an increased mitochondrial AP endonuclease (mtAPE1) activity, while restoration of estrogen levels by exogenous supplementation resulted in restitution of control APE1 activity only in liver. Moreover, in hepatic mitochondria, changes in estrogen levels affected the processing of oxidative lesions but not deaminations. Our results suggest that changes in mtAPE1 activity are related to specific translocation of the enzyme from the cytosol into the mitochondria probably due to oxidative stress changes as a consequence of changes in estrogen levels.

Supplementation with essential amino acids in middle age maintains the health of rat kidney

Chronic kidney diseases are a social and economic problem, and diet has long been recognized as a fundamental modulator of kidney health in human and experimental models. Age-dependent alterations in mitochondrial function play a crucial role in the development of diseases of aging, and mitochondrial disorders have been observed in experimental models of kidney failure. Recently, the beneficial dietary effect of a specific mixture of essential amino acids (EAA) has been studied in elderly subjects, but no data were collected from the kidney. The aim of this study was to assess whether daily supplementation of the diet with EAA at the beginning of senescence could preserve renal health. We used middle-aged (18-month-old) male Wistar rats fed a standard diet and water ad libitum (M-aged group) or a diet with added EAA (1.5 g/kg per day) dissolved in drinking water for 3 months (M-aged+EAA group). Young (2-month-old) rats fed a standard diet for 3 months were used as controls. Mitochondrial morphology and markers for collagen, cyt-c-oxidase, HSP60, GRP75, eNOS, iNOS, Bax, Bcl2 and VEGF were analyzed in glomeruli and tubules. EAA supplementation limited fibrosis and increased the capillary tuft area in the glomeruli of M-aged rats. VEGF and eNOS were enhanced in glomeruli and the peritubular space with the EAA-supplemented diet. Mitochondrial cyt-c oxidase, Bcl2, and chaperones increased in the distal tubules of the EAA group to levels similar to those observed in the young group. Mitochondrial area and density after EAA intake did not differ from young groups. The results suggest that prolonged EAA intake could represent a strategy for maintaining the healthy status of the kidney in M-aged animals.

Adult-onset calorie restriction delays the accumulation of mitochondrial enzyme abnormalities in aging rat kidney tubular epithelial cells

Adult-onset calorie restriction (A-CR) is an experimental model of life extension and healthy aging less explored, compared with calorie restriction begun at early ages, but one more realistic for human application. We examined the effect of A-CR on the aging rat kidney with respect to common structural age-dependent changes and the accumulation of mitochondrial enzyme abnormalities in tubular epithelial cells. A 40% calorie restriction was initiated in middle-aged rats, before the onset of significant age-related changes in the Fischer x Brown Norway rat kidney. This dietary intervention effectively reduced glomerulosclerosis and tubular atrophy within 6 mo and changed the rate of interstitial fibrosis formation within 1 yr and vascular wall thickening and the expression cytochrome c oxidase (COX)-deficient tubular epithelial cells in 18 mo compared with age-matched ad libitum-fed rats. Our histological approach (histochemical staining for mitochondrial enzyme activity and laser capture microdissection) coupled with mitochondrial DNA (mtDNA) PCR analyses demonstrated that COX-deficient renal tubular epithelial cells accumulated mtDNA deletion mutations and that these cells contained unique, clonally expanded mtDNA deletion mutations. Renal tubular epithelial cells with mitochondrial abnormalities presented cellular characteristics indicative of physiological dysfunction.