Caloric restriction has been correlated with many beneficial effects on human body. For example it delays aging and possibly delays the development of Alzheimer’s disease. But the molecular mechanisms underlying these benefits are not clear. Researches are in progress to determine the molecular changes due to caloric restriction. A group of scientists at Nutrition Obesity Research Center, University of Albama at Birmingham, USA are working on this topic. One of their research papers recently published in PLOS ONE (doi:10.1371/journal.pone.0060437) has described the effect of hunger induced by ghrelin agonist. Ghrelin is a 28 amino acid hunger-stimulating peptide. Agonist of this peptide is used in this study to mimic the feeling of hunger. Ghrelin levels increase before meals and decrease after meals. It is considered the counterpart of the hormone leptin, produced by adipose tissue, which induces satiation when present at higher levels. In this study, transgenic APP-SwDI mouse model of Alzheimer’s disease (AD) is used. Different behavioral, cognitive analysis along with immunohistochemistry and ELISA were performed to measure the difference in control, calorie restricted and ghrelin agonist (LY)-given mouse. The results showed that, ghrelin agonist (LY)-given mouse gained similar body weight like control and the effect of AD is much severe in control than LY-treated mouse. The primary pathogenesis in AD arises from the formation and deposition of amyloid (Aß) plaque in the forebrain. A previous study showed that, the caloric restriction significantly reduced the amyloid deposition in AD model mouse. But in this study they found similar reduction of insoluble Aß in LY-treated and calorie restricted mouse. This finding just completed a long unresolved puzzle. More study may shed light on the molecular mechanisms of the phenomenon of ‘hunger’. And these studies will help us to design and develop implement new strategies to combat obesity-related diseases and to delaying the aging process. [summarized by Md. Muntasir Ali – graduate student of Plant Biotech Lab. DU.]
Md. Muntasir Ali
MS(Thesis Student), Plant Biotechnology Lab, Department of Biochemistry & Molecular Biology, University of Dhaka.