Adipose tissue gene expression profiles of healthy young adult and geriatric dogs

Abstract

Obesity is a major problem in today's dog population, with aged animals having an increased susceptibility to obesity-related comorbidities. A molecular approach to studying adipose tissue may enhance our understanding of its role in energy homeostasis and the disease process. Thus, the objective of this study was to use canine microarrays to compare gene expression profiles of adipose tissue from geriatric and young adult dogs. Adipose tissue samples were collected from six geriatric (12 year-old) and six young adult (one-year-old) female beagles after being fed one of two diets (animal protein-based vs. plant protein-based) for 12 months. RNA samples were hybridised to canine microarrays. Statistical analyses indicated that age had the greatest impact on gene expression, with 65 differentially expressed gene transcripts in geriatric dogs. Diet had a minor impact on gene expression, altering the expression of only 19 gene transcripts. In general, adipose tissue of geriatric dogs had increased expression of genes associated with cell cycle and growth, cell development and structure, cellular trafficking and protein processing, immune function, metabolism, and transcription and translation, as compared with that of young adults. Overall, our mRNA data suggest either an increased population of macrophages or increased inflammatory nature of adipocytes in adipose tissue of aged dogs.

Gene Expression Profiles of Colonic Mucosa in Healthy Young Adult and Senior Dogs

“…The fact that most gene expression differences were attributed to age in this experiment agrees with our previous experiments focused on gene expression in cerebral cortex [11], skeletal muscle [12], and abdominal adipose [13] tissues from these same dogs. Of the 14,217 genes expressed by colon mucosa, 1.49% (212/14,217) were significantly altered due to age.…”

“…Our previous experiments also reported age as the primary factor affecting gene expression changes, with a small percentage of genes being altered. In short, only 0.25% of genes in adipose tissue [13], 2.91% of genes in skeletal muscle [12], and 6.48% of genes in cerebral cortex [11] were differentially expressed due to age. The small number of genes altered by age in this experiment is in agreement with previous microarray data from muscle [9], duodenum, and colon [16] tissues of aged vs. young mice.…”

“…Previously, we reported the effects of diet (APB; animal protein-based vs. PPB; plant protein-based) and age (young adult vs. senior dogs) on gene expression profiles of cerebral cortex [11], skeletal muscle [12], and abdominal adipose tissues [13]. To our knowledge, no large-scale molecular analysis of colonic mucosa in young adult vs. senior dogs is available.…”

The beneficial role of anti-inflammatory dietary ingredients in attenuating markers of chronic low-grade inflammation in aging

“…This study highlights the importance of inflammation in aging and various disease conditions and the benefit that may be achieved by reducing chronic inflammation. Also, adipose tissue gene expression indicates that there is an increased number of macrophages in adipocytes of older dogs (12 years) when compared with young dogs (1 year) [8], and this may contribute to systemic low-grade inflammation. The molecular mechanisms underlying various agingassociated disorders are likely not the same although they are all associated with low-level inflammation.…”

Nutrition of Aging Dogs

“…36 Within adipose tissue, aging effects were more minimal, with alteration of expression of genes related to immune function and inflammatory response. 37 The clinical effects of these findings, if any, remain unclear.…”