Transgenic mice expressing yeast CUP1 exhibit increased copper utilization from feeds

Chronic corticosterone-induced depression mediates premature aging in rats

BACKGROUND

Stress hormones such as corticosterone (CORT) play an essential role in the development of depression. Chronic CORT administration has been shown to induce dysfunction in the hypothalamic-pituitary-adrenal axis leading to depression, which was in turn associated with accelerated aging. However, the effect of CORT administration on aging remains unclear.

METHODS

Rats were acclimatized for 1 week and then injected daily with CORT (40mg/kg) or vehicle (n = 10 each) for 21 consecutive days. Age-related indexes were then compared between CORT-treated rats and control rats.

RESULTS

CORT induced affective behaviors indicative of depressive-like symptoms in rats, including reduced sucrose preference and increased immobility time in the forced swimming test. CORT-treated rats exhibited telomere shortening, possibly contributing to decreased telomerase activity and down-regulated expression of telomere-binding factor 2, correlated with enhanced oxidative damage. This was associated with inhibition of sirtuin 3 leading to reduced activities of superoxide dismutase 2 and glutathione reductase. CORT-treated rats showed degenerated mitochondrial functions represented by decreased adenosine triphosphate production, decreased nicotinamide adenine dinucleotide⁺ content, and decreased activity of nicotinamide phosphoribosyltransferase.

LIMITATIONS

The group sample sizes were small, and only male rats and a single dose level of CORT were used.

CONCLUSION

These findings demonstrate that CORT-induced depression may be involved in mediating the pathophysiology of premature aging in rats.

Preventive Effect of L-Carnitine on the Disorder of Lipid Metabolism and Circadian Clock of Mice Subjected to Chronic Jet-Lag

Circadian clock plays an essential role in orchestrating daily physiology, and its disruption can evoke metabolic diseases such as obesity. L-Carnitine can reduce blood lipid levels, and ameliorate fatty liver through regulating lipid metabolism. However, whether L-Carnitine administration may affect the disturbance of lipid metabolism and circadian rhythm of mice induced by prolonged circadian disruption is still unknown. Herein, we investigated the effects of L-Carnitine on conditions of circadian clock and lipid metabolism through a chronic jet-lag mice model which was developed by reversing 12 h light/12 h dark cycle every 4 days for a continuous 12 weeks. Results showed that L-Carnitine administration significantly decreased levels of serum glutamic-oxaloacetic transaminase (GOT) and triglycerides (TG), which were remarkably elevated by chronic jet-lag. More importantly, quantitative real-time polymerase chain reaction (qRT-PCR) analysis indicated that L-Carnitine supplementation would effectively counteract the negative alterations in gene expression which related to lipid metabolism (Srebp1, Acaca, Fasn, and Scd1), metabolic regulator (mTOR) and circadian rhythm (Bmal1, Per1, Cry1 and Dec1) in the liver of mice subjected to the chronic jet-lag. As a conclusion, L-Carnitine was partly effective in preventing the disruption of circadian clock and lipid metabolic disorders induced by the chronic jet-lag.

Desipramine rescues age-related phenotypes in depression-like rats induced by chronic mild stress

AIMS

Our previous finding demonstrates that major depressive disorder can mediate accelerated aging in rats. Desipramine is a typical tricyclic antidepressant, and can provide neuroprotection and counteract depression-like behaviors. However, whether desipramine can rescue age-related phenotypes in depressed individuals is not understood. In the present study, we investigated the physiological function of desipramine on rescuing the age-related phenotypes in these animals.

MAIN METHODS

The rats were induced by chronic mild stress paradigm, and the depression-like behaviors of rats were detected by sucrose intake test, open field test (OFT) and forced swimming test (FST). Then the depressed rats were treated by desipramine.

KEY FINDINGS

Desipramine administration was effective in counteracting depression-like behaviors by increasing the sucrose solution intake, reducing the immobility time in the FST, and increasing total distance travelled and numbers of grid line crossed in the OFT. Moreover, desipramine treatment was able to reduce the oxidative damage to rat liver, and to increase the expression of telomerase reverse transcriptase (TERT), leading to correspondingly restored telomerase activity.

SIGNIFICANCE

Our findings identify that one function of desipramine may partly be to rescue age-related phenotypes in depressed individuals induced by chronic stress.