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The Effects of Aging on the Gene Expression of Adrenomedullin and its Receptor Protein Components in the Rat: Possible Implication in Insulin Resistance in Skeletal Muscle and Adipose Tissue
Author(s) -
Chow Heiman,
Tang Fai
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a154-c
Subject(s) - medicine , endocrinology , amylin , adrenomedullin , insulin resistance , adipose tissue , insulin receptor , receptor , insulin , skeletal muscle , lipolysis , calcitonin receptor , biology , calcitonin gene related peptide , neuropeptide , islet
People's Republic of Insulin resistance has been known to be associated with aging and obesity, and recent studies have turned to the roles of local hormones including adipokines. Amylin and calcitonin gene‐related peptide (CGRP) have shown to induce insulin resistance. We report here similar effects of adrenomedullin (AM), another peptide of the same family. It inhibits insulin‐stimulated glucose uptake in soleus muscle strips, epididymal fat pads and 3T3‐L1 cells and increases lipolysis in the adipocytes. Given that increase in insulin resistance is associated with obesity, we hypothesize there may be changes in the gene expression of AM and its receptor component proteins during aging. Skeletal muscles and adipose tissues from rats aged 3 months, 12 months and 20 months were obtained and the mRNA levels of AM, its receptor (CRLR, or calcitonin receptor‐like receptor) and its receptor activity modifying proteins (RAMPs) were found to decrease during aging. As the effect of AM is to decrease insulin sensitivity and to increase lipolysis, it is concluded that decreases in gene expression of AM and its receptor in skeletal muscle and fat during aging may be a compensatory response rather than a contributing factor to the increase in insulin resistance. This project is supported by a RGC grant.