Effect of stress due to food deprivation, social inequality and instability on brain lipofuscin levels

Introduction: Several reports show a relationship between health equity, and health status and longevity of individuals. In this study, effects of food deprivation, inequality and social instability were investigated on the formation of lipofuscin pigment in Balb/C mice by histopathological and biochemical methods. Methods: Thirty-six male mice were divided into 6 groups, then different kinds of stress (food deprivation, inequality and cage-mate change) were implemented on these groups for 2 weeks according to the protocol. Lipofuscin was biochemically measured in the brain homogenate of one hemisphere by Shen's method. The other brain hemisphere was used to qualitatively investigate the accumulation of lipofuscin by fluorescent microscope and it was also stain ed with periodic acid Schiff and examined with light microscope. Results: Food deprivation alone did not cause significant differences in the amount of lipofuscin, but in food deprived and inequality experienced animals the amounts of lipofuscin was well a bove controls (P<0.05); moreover, in the mice, which merely experienced unstable social status, the increase of lipofuscin was significant compared to the controls (P<0.001). When all of three social stresses were applied simultaneously, lipofuscin changes were more obvious. The microscopic examination of tissue samples showed accumulation of lipofuscin in test conditions. Conclusion: Food deprivation, injustice and unstable social status, especially when are applied simultaneously, can increase brain lipofuscin levels. Considering the role of this pigment in aging, the probability of appearance of early aging can be considered after exposure to social stress.