1. IntroductionAging can be defined as anatural and universal process causing progressive loss of physiological integrityand functions of body that results in decline in all the biological systems includingbut not limited to molecular interaction, cellular functions, tissue structureand function as well as systemic physiological homeostasis.1,2 It also causes accumulation ofseveral deleterious factors, which increases the susceptibility to severaltypes of diseases and infections.3 All these factors result inprogressive increase in mortality.
The advances in medical field and publichealth have helped increase the life expectancy which has resulted in upsurgein the number of elderly population.4 The increasing focus ofresearchers on aging researches has helped unlocking several questionsregarding aging. Aging has found to be modulated by combination of genetic andenvironmental conditions.5,6 Of the environmentalconditions, food is one of the major factors that influences aging.7 Calories Restriction (CR) hasshown to extend lifespan in several species.
N-Acetylcysteine has also shown toslow the aging process and extend the life span. However, the exact underlyingmechanism for the extension by both food and N-Acetylcysteine are yet to becompletely explored. 8,9In this research we tried to determinethe mechanism of life span extension by calorie restriction andN-acetylcysteine. In aim (a) we analyzed the roleof CR in increasing locomotory activity of drosophila. Calorie restriction isthe calorie intake reduction without causing malnutrition. CR has shown toincrease locomotory activity in different species. 10–12 It not only increases the lifespan but also delays several age related symptoms, which ultimately helps inimproving the quality of life. Shortened level of particular renal gene hasshown to lead to a shortened life suggesting the roles of expression level ofrenal genes in extension of life span.
13 In this research we have shownincrease in locomotory activity induced by dietary restriction increases thelife span. In aim (b) we analyzed the role of in alteration of expression levels ofROS (Reactive Oxygen Species) scavenger genes. N-acetylcysteine is the N-acetylderivative of cysteine and has been medically in use for the treatment ofparacetamol overdose and as mucolytic agent. The antioxidant N-acetylcysteineis known as radical scavenger and/or cysteine donor. It also works as precursorfor glutathione.webpage9 ROS are the byproducts of cell metabolism and the accumulation of whichhas detrimental effect on several cellular component causing cell damage.
14 In the 2nd part of our research, we have shown thatscavenging of these ROS by increased expression of ROS scavenger genes resultsin increase in life span. We used Drosophila as in vivo model in our research in orderto reveal the mechanism of life span extension by calorie restriction andN-acetylcysteine. The use of drosophila accounts to ease of handling, cheapcost and about 70% of drosophila genes having human homologs.
Apart from this, ithas relatively short life span. Also, the fly is composed of post-mitoticcells, which is well suited for the study of aging mechanisms.9,15 Key genes and major pathwaysare evolutionary preserved in between human and drosophila, which also supportsthe use of drosophila in research. 16. Studies have shown that bothdietary restriction and N-acetylcysteine have promising effects on improvingquality of health and life span.
We have tried to put light on the mechanism oflife span extension. We hope that our research would enlarge the understandingof mechanism behind life span extension from calorie restriction andN-Acetylcysteine and would pave path for further researches in this topic.