Molecular mechanisms of life- and health-span extension: role of calorie restriction and exercise intervention

Caloric restriction and brain function

PURPOSE OF REVIEW

In addition to extending lifespan, animal research shows that specific diets benefit brain functioning. Indeed, it has been proven that caloric restriction prevents age-related neuronal damage. What are those mechanisms involved in the effects of caloric restriction on brain functioning? Could caloric restriction be proposed in the future to prevent or treat neurodegenerative disorders such as Alzheimer's disease? Is there a future for caloric restriction interventions in adults?

RECENT FINDINGS

Hypotheses linking caloric restriction to cognitive capability include anti-inflammatory mechanisms, reduction of neural oxidative stress, promotion of synaptic plasticity, induction of various stress and neurotrophic/neuroprotective factors. Caloric restriction may also prevent beta-amyloid neuropathology in Alzheimer transgenic models. Finally, both exercise and caloric restriction enhance neurogenesis via different mechanisms suggesting that their combination may decrease the risk of neurodegenerative disease.

SUMMARY

It is now well established that caloric restriction could be used to promote successful brain aging. Data from randomized controlled trials in humans are limited. No positive effect on cognitive impairment was found probably due to methodological limitations. The long-term effects of caloric restriction in adults must be clarified before engaging in such preventive strategy. Additional animal studies must be conducted in the future to test the effects of 'multidomain' interventions (caloric restriction plus regular exercise) on age-related cognitive decline.

Sustained cardioprotection: exploring unconventional modalities

Since Murry et al. [Murry, C.E., Jennings, R.B., Reimer, K.A., 1986. Preconditioning with ischemia: a delay of lethal cell injury in ischemic myocardium. Circulation. 74, 1124-36.] initially reported on the powerful protective effects of ischemic preconditioning (PC), a plethora of experimental investigations have identified varied preconditioning protocols or mimetics to achieve cardioprotection. These stimuli predominantly act via archetypal mediators identified in associated signalling studies (including PI3-K, Akt, PKC, mitochondrial K(ATP) channels). Despite an intense research effort over the last 20 years, there remains a paucity of evidence that this protective paradigm is clinically exploitable. This may arise due to a number of drawbacks to conventional protection, including effects of age, disease, and interactions with other pharmacological agents. This encourages investigation of alternate strategies that trigger protection via unconventional signalling (distinct from conventional PC) and/or mediate sustained shifts in ischemic tolerance in hearts of varying age and disease status. This review considers briefly drawbacks to conventional PC, and focuses on alternate strategies for generating prolonged states of cardiac protection.